@article {924, title = {Mutations in Spliceosomal Genes PPIL1 and PRP17 Cause Neurodegenerative Pontocerebellar Hypoplasia with Microcephaly.}, journal = {Neuron}, volume = {109}, year = {2021}, month = {2021 01 20}, pages = {241-256.e9}, abstract = {

Autosomal-recessive cerebellar hypoplasia and ataxia constitute a group of heterogeneous brain disorders caused by disruption of several fundamental cellular processes. Here, we identified 10 families showing a neurodegenerative condition involving pontocerebellar hypoplasia with microcephaly (PCHM). Patients harbored biallelic mutations in genes encoding the spliceosome components Peptidyl-Prolyl Isomerase Like-1 (PPIL1) or Pre-RNA Processing-17 (PRP17). Mouse knockouts of either gene were lethal in early embryogenesis, whereas PPIL1 patient mutation knockin mice showed neuron-specific apoptosis. Loss of either protein affected splicing integrity, predominantly affecting short and high GC-content introns and genes involved in brain disorders. PPIL1 and PRP17 form an active isomerase-substrate interaction, but we found that isomerase activity is not critical for function. Thus, we establish disrupted splicing integrity and "major spliceosome-opathies" as a new mechanism underlying PCHM and neurodegeneration and uncover a non-enzymatic function of a spliceosomal proline isomerase.

}, keywords = {Amino Acid Sequence, Animals, Cell Cycle Proteins, Cerebellar Diseases, Cohort Studies, Female, Gene Knockout Techniques, HEK293 Cells, Heredodegenerative Disorders, Nervous System, Humans, Male, Mice, Mice, Inbred C57BL, Mice, Transgenic, Microcephaly, Mutation, Pedigree, Peptidylprolyl Isomerase, Protein Structure, Secondary, Protein Structure, Tertiary, RNA Splicing Factors, Spliceosomes}, issn = {1097-4199}, doi = {10.1016/j.neuron.2020.10.035}, author = {Chai, Guoliang and Webb, Alice and Li, Chen and Antaki, Danny and Lee, Sangmoon and Breuss, Martin W and Lang, Nhi and Stanley, Valentina and Anzenberg, Paula and Yang, Xiaoxu and Marshall, Trevor and Gaffney, Patrick and Wierenga, Klaas J and Chung, Brian Hon-Yin and Tsang, Mandy Ho-Yin and Pais, Lynn S and Lovgren, Alysia Kern and VanNoy, Grace E and Rehm, Heidi L and Mirzaa, Ghayda and Leon, Eyby and Diaz, Jullianne and Neumann, Alexander and Kalverda, Arnout P and Manfield, Iain W and Parry, David A and Logan, Clare V and Johnson, Colin A and Bonthron, David T and Valleley, Elizabeth M A and Issa, Mahmoud Y and Abdel-Ghafar, Sherif F and Abdel-Hamid, Mohamed S and Jennings, Patricia and Zaki, MAH S and Sheridan, Eamonn and Gleeson, Joseph G} } @article {779, title = {Bi-allelic ADARB1 Variants Associated with Microcephaly, Intellectual Disability, and Seizures.}, journal = {Am J Hum Genet}, volume = {106}, year = {2020}, month = {2020 04 02}, pages = {467-483}, abstract = {

The RNA editing enzyme ADAR2 is essential for the recoding of brain transcripts. Impaired ADAR2 editing leads to early-onset epilepsy and premature death in a mouse model. Here, we report bi-allelic variants in ADARB1, the gene encoding ADAR2, in four unrelated individuals with microcephaly, intellectual disability, and epilepsy. In one individual, a homozygous variant in one of the double-stranded RNA-binding domains (dsRBDs) was identified. In the others, variants were situated in or around the deaminase domain. To evaluate the effects of these variants on ADAR2 enzymatic activity, we performed in~vitro assays with recombinant proteins in HEK293T cells and ex~vivo assays with fibroblasts derived from one of the individuals. We demonstrate that these ADAR2 variants lead to reduced editing activity on a known ADAR2 substrate. We also demonstrate that one variant leads to changes in splicing of ADARB1 transcript isoforms. These findings reinforce the importance of RNA editing in brain development and introduce ADARB1 as a genetic etiology in individuals with intellectual disability, microcephaly, and epilepsy.

}, keywords = {Adenosine Deaminase, Alleles, Alternative Splicing, Child, Child, Preschool, Genetic Predisposition to Disease, Genetic Variation, HEK293 Cells, Humans, Intellectual Disability, Male, Microcephaly, RNA Splicing, RNA-Binding Proteins, Seizures}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2020.02.015}, author = {Tan, Tiong Yang and Sedm{\'\i}k, Ji{\v r}{\'\i} and Fitzgerald, Mark P and Halevy, Rivka Sukenik and Keegan, Liam P and Helbig, Ingo and Basel-Salmon, Lina and Cohen, Lior and Straussberg, Rachel and Chung, Wendy K and Helal, Mayada and Maroofian, Reza and Houlden, Henry and Juusola, Jane and Sadedin, Simon and Pais, Lynn and Howell, Katherine B and White, Susan M and Christodoulou, John and O{\textquoteright}Connell, Mary A} } @article {758, title = {Biallelic GRM7 variants cause epilepsy, microcephaly, and cerebral atrophy.}, journal = {Ann Clin Transl Neurol}, volume = {7}, year = {2020}, month = {2020 05}, pages = {610-627}, abstract = {

OBJECTIVE: Defects in ion channels and neurotransmitter receptors are implicated in developmental and epileptic encephalopathy (DEE). Metabotropic glutamate receptor 7 (mGluR7), encoded by GRM7, is a presynaptic G-protein-coupled glutamate receptor critical for synaptic transmission. We previously proposed GRM7 as a candidate disease gene in two families with neurodevelopmental disorders (NDDs). One additional family has been published since. Here, we describe three additional families with GRM7 biallelic variants and deeply characterize the associated clinical neurological and electrophysiological phenotype and molecular data in 11 affected individuals from six unrelated families.

METHODS: Exome sequencing and family-based rare variant analyses on a cohort of 220 consanguineous families with NDDs revealed three families with GRM7 biallelic variants; three additional families were identified through literature search and collaboration with a clinical molecular laboratory.

RESULTS: We compared the observed clinical features and variants of 11 affected individuals from the six unrelated families. Identified novel deleterious variants included two homozygous missense variants (c.2671G>A:p.Glu891Lys and c.1973G>A:p.Arg685Gln) and one homozygous stop-gain variant (c.1975C>T:p.Arg659Ter). Developmental delay, neonatal- or infantile-onset epilepsy, and microcephaly were universal. Three individuals had hypothalamic-pituitary-axis dysfunction without pituitary structural abnormality. Neuroimaging showed cerebral atrophy and hypomyelination in a majority of cases. Two siblings demonstrated progressive loss of myelination by 2~years in both and an acquired microcephaly pattern in one. Five individuals died in early or late childhood.

CONCLUSION: Detailed clinical characterization of 11 individuals from six unrelated families demonstrates that rare biallelic GRM7 pathogenic variants can cause DEEs, microcephaly, hypomyelination, and cerebral atrophy.

}, keywords = {Adolescent, Alleles, Atrophy, Child, Child, Preschool, Cohort Studies, Consanguinity, Epilepsy, Female, Humans, Infant, Male, Microcephaly, Neurodevelopmental Disorders, Pedigree, Phenotype, Receptors, Metabotropic Glutamate, Whole Exome Sequencing}, issn = {2328-9503}, doi = {10.1002/acn3.51003}, author = {Marafi, Dana and Mitani, Tadahiro and Isikay, Sedat and Hertecant, Jozef and Almannai, Mohammed and Manickam, Kandamurugu and Abou Jamra, Rami and El-Hattab, Ayman W and Rajah, Jaishen and Fatih, Jawid M and Du, Haowei and Karaca, Ender and Bayram, Yavuz and Punetha, Jaya and Rosenfeld, Jill A and Jhangiani, Shalini N and Boerwinkle, Eric and Akdemir, Zeynep C and Erdin, Serkan and Hunter, Jill V and Gibbs, Richard A and Pehlivan, Davut and Posey, Jennifer E and Lupski, James R} } @article {738, title = {Deficiencies in vesicular transport mediated by TRAPPC4 are associated with severe syndromic intellectual disability.}, journal = {Brain}, volume = {143}, year = {2020}, month = {2020 01 01}, pages = {112-130}, abstract = {

The conserved transport protein particle (TRAPP) complexes regulate key trafficking events and are required for autophagy. TRAPPC4, like its yeast Trs23 orthologue, is a core component of the TRAPP complexes and one of the essential subunits for guanine nucleotide exchange factor activity for Rab1 GTPase. Pathogenic variants in specific TRAPP subunits are associated with neurological disorders. We undertook exome sequencing in three unrelated families of Caucasian, Turkish and French-Canadian ethnicities with seven affected children that showed features of early-onset seizures, developmental delay, microcephaly, sensorineural deafness, spastic quadriparesis and progressive cortical and cerebellar atrophy in an effort to determine the genetic aetiology underlying neurodevelopmental disorders. All seven affected subjects shared the same identical rare, homozygous, potentially pathogenic variant in a non-canonical, well-conserved splice site within TRAPPC4 (hg19:chr11:g.118890966A>G; TRAPPC4: NM_016146.5; c.454+3A>G). Single nucleotide polymorphism array analysis revealed there was no haplotype shared between the tested Turkish and Caucasian families suggestive of a variant hotspot region rather than a founder effect. In silico analysis predicted the variant to cause aberrant splicing. Consistent with this, experimental evidence showed both a reduction in full-length transcript levels and an increase in levels of a shorter transcript missing exon 3, suggestive of an incompletely penetrant splice defect. TRAPPC4 protein levels were significantly reduced whilst levels of other TRAPP complex subunits remained unaffected. Native polyacrylamide gel electrophoresis and size exclusion chromatography demonstrated a defect in TRAPP complex assembly and/or stability. Intracellular trafficking through the Golgi using the marker protein VSVG-GFP-ts045 demonstrated significantly delayed entry into and exit from the Golgi in fibroblasts derived from one of the affected subjects. Lentiviral expression of wild-type TRAPPC4 in these fibroblasts restored trafficking, suggesting that the trafficking defect was due to reduced TRAPPC4 levels. Consistent with the recent association of the TRAPP complex with autophagy, we found that the fibroblasts had a basal autophagy defect and a delay in autophagic flux, possibly due to unsealed autophagosomes. These results were validated using a yeast trs23 temperature sensitive variant that exhibits constitutive and stress-induced autophagic defects at permissive temperature and a secretory defect at restrictive temperature. In summary we provide strong evidence for pathogenicity of this variant in a member of the core TRAPP subunit, TRAPPC4 that associates with vesicular trafficking and autophagy defects. This is the first report of a TRAPPC4 variant, and our findings add to the growing number of TRAPP-associated neurological disorders.

}, keywords = {Atrophy, Autophagy, Cerebellum, Cerebral Cortex, Child, Child, Preschool, Craniofacial Abnormalities, Deafness, Developmental Disabilities, Epilepsy, Female, Fibroblasts, Hearing Loss, Sensorineural, Humans, Infant, Infant, Newborn, Intellectual Disability, Male, Microcephaly, Microscopy, Fluorescence, Muscle Spasticity, Nerve Tissue Proteins, Neurodevelopmental Disorders, Pedigree, Quadriplegia, RNA Splice Sites, Syndrome, Vesicular Transport Proteins}, issn = {1460-2156}, doi = {10.1093/brain/awz374}, author = {Van Bergen, Nicole J and Guo, Yiran and Al-Deri, Noraldin and Lipatova, Zhanna and Stanga, Daniela and Zhao, Sarah and Murtazina, Rakhilya and Gyurkovska, Valeriya and Pehlivan, Davut and Mitani, Tadahiro and Gezdirici, Alper and Antony, Jayne and Collins, Felicity and Willis, Mary J H and Coban Akdemir, Zeynep H and Liu, Pengfei and Punetha, Jaya and Hunter, Jill V and Jhangiani, Shalini N and Fatih, Jawid M and Rosenfeld, Jill A and Posey, Jennifer E and Gibbs, Richard A and Karaca, Ender and Massey, Sean and Ranasinghe, Thisara G and Sleiman, Patrick and Troedson, Chris and Lupski, James R and Sacher, Michael and Segev, Nava and Hakonarson, Hakon and Christodoulou, John} } @article {804, title = {Loss of NARS1 impairs progenitor proliferation in cortical brain organoids and leads to microcephaly.}, journal = {Nat Commun}, volume = {11}, year = {2020}, month = {2020 08 12}, pages = {4038}, abstract = {

Asparaginyl-tRNA synthetase1 (NARS1) is a member of the ubiquitously expressed cytoplasmic Class IIa family of tRNA synthetases required for protein translation. Here, we identify biallelic missense and frameshift mutations in NARS1 in seven patients from three unrelated families with microcephaly and neurodevelopmental delay. Patient cells show reduced NARS1 protein, impaired NARS1 activity and impaired global protein synthesis. Cortical brain organoid modeling shows reduced proliferation of radial glial cells (RGCs), leading to smaller organoids characteristic of microcephaly. Single-cell analysis reveals altered constituents of both astrocytic and RGC lineages, suggesting a requirement for NARS1 in RGC proliferation. Our findings demonstrate that NARS1 is required to meet protein synthetic needs and to support RGC proliferation in human brain development.

}, keywords = {Adolescent, Adult, Aspartate-tRNA Ligase, Base Sequence, Cell Differentiation, Cell Proliferation, Cell Size, Cell Survival, Cerebral Cortex, Child, Family, Female, Fibroblasts, HEK293 Cells, Humans, Induced Pluripotent Stem Cells, Ki-67 Antigen, Male, Microcephaly, Mutation, Neural Stem Cells, Neuroglia, Organoids, Pedigree, RNA, Transfer, Amino Acyl, Young Adult}, issn = {2041-1723}, doi = {10.1038/s41467-020-17454-4}, author = {Wang, Lu and Li, Zhen and Sievert, David and Smith, Desir{\'e}e E C and Mendes, Marisa I and Chen, Dillon Y and Stanley, Valentina and Ghosh, Shereen and Wang, Yulu and Kara, Majdi and Aslanger, Ayca Dilruba and Rosti, Rasim O and Houlden, Henry and Salomons, Gajja S and Gleeson, Joseph G} } @article {707, title = {Phenotypic expansion of POGZ-related intellectual disability syndrome (White-Sutton syndrome).}, journal = {Am J Med Genet A}, volume = {182}, year = {2020}, month = {2020 01}, pages = {38-52}, abstract = {

White-Sutton syndrome (WHSUS) is a recently-identified genetic disorder resulting from de novo heterozygous pathogenic variants in POGZ. Thus far, over 50 individuals have been reported worldwide, however phenotypic characterization and data regarding the natural history are still incomplete. Here we report the clinical features of 22 individuals with 21 unique loss of function POGZ variants. We observed a broad spectrum of intellectual disability and/or developmental delay with or without autism, and speech delay in all individuals. Other common problems included ocular abnormalities, hearing loss and gait abnormalities. A validated sleep disordered breathing questionnaire identified symptoms of obstructive sleep apnea in 4/12 (33\%) individuals. A higher-than-expected proportion of cases also had gastrointestinal phenotypes, both functional and anatomical, as well as genitourinary anomalies. In line with previous publications, we observed an increased body mass index (BMI) z-score compared to the general population (mean 0.59, median 0.9; p 0.0253). Common facial features included microcephaly, broad forehead, midface hypoplasia, triangular mouth, broad nasal root and flat nasal bridge. Analysis of the Baylor Genetics clinical laboratory database revealed that POGZ variants were implicated in approximately 0.14\% of cases who underwent clinical exome sequencing for neurological indications with or without involvement of other body systems. This study describes a greater allelic series and expands the phenotypic spectrum of this new syndromic form of intellectual disability and autism.

}, keywords = {Adolescent, Adult, Autistic Disorder, Child, Child, Preschool, Exome, Female, Heterozygote, Humans, Infant, Intellectual Disability, Language Development Disorders, Male, Microcephaly, Middle Aged, Mutation, Phenotype, Transposases, Whole Exome Sequencing, Young Adult}, issn = {1552-4833}, doi = {10.1002/ajmg.a.61380}, author = {Assia Batzir, Nurit and Posey, Jennifer E and Song, Xiaofei and Akdemir, Zeynep Coban and Rosenfeld, Jill A and Brown, Chester W and Chen, Emily and Holtrop, Shannon G and Mizerik, Elizabeth and Nieto Moreno, Margarita and Payne, Katelyn and Raas-Rothschild, Annick and Scott, Richard and Vernon, Hilary J and Zadeh, Neda and Lupski, James R and Sutton, V Reid} } @article {956, title = {Recurrent homozygous damaging mutation in , encoding a protein disulfide isomerase, in four families with microlissencephaly.}, journal = {J Med Genet}, volume = {57}, year = {2020}, month = {2020 04}, pages = {274-282}, abstract = {

BACKGROUND: Protein disulfide isomerase (PDI) proteins are part of the thioredoxin protein superfamily. PDIs are involved in the formation and rearrangement of disulfide bonds between cysteine residues during protein folding in the endoplasmic reticulum and are implicated in stress response pathways.

METHODS: Eight children from four consanguineous families residing in distinct geographies within the Middle East and Central Asia were recruited for study. All probands showed structurally similar microcephaly with lissencephaly (microlissencephaly) brain malformations. DNA samples from each family underwent whole exome sequencing, assessment for repeat expansions and confirmatory segregation analysis.

RESULTS: An identical homozygous variant in (c.500G>A), encoding thioredoxin-related transmembrane protein 2, segregated with disease in all four families. This variant changed the last coding base of exon 6, and impacted mRNA stability. All patients presented with microlissencephaly, global developmental delay, intellectual disability and epilepsy. While is an activator of cellular repeat expansion toxicity, patients showed no evidence of repeat expansions.

CONCLUSION: The c.500G>A allele associates with recessive microlissencephaly, and patients show no evidence of expansions. is the first PDI implicated in a recessive disease, suggesting a protein isomerisation defect in microlissencephaly.

}, keywords = {Amino Acid Sequence, Child, Child, Preschool, Consanguinity, Endoplasmic Reticulum, Exons, Female, Genetic Predisposition to Disease, Homozygote, Humans, Male, Membrane Proteins, Microcephaly, Mutation, Protein Disulfide-Isomerases, Protein Folding, Thioredoxins, Whole Exome Sequencing}, issn = {1468-6244}, doi = {10.1136/jmedgenet-2019-106409}, author = {Ghosh, Shereen Georges and Wang, Lu and Breuss, Martin W and Green, Joshua D and Stanley, Valentina and Yang, Xiaoxu and Ross, Danica and Traynor, Bryan J and Alhashem, Amal M and Azam, Matloob and Selim, Laila and Bastaki, Laila and Elbastawisy, Hanan I and Temtamy, Samia and Zaki, MAH and Gleeson, Joseph G} } @article {746, title = {Regulation of human cerebral cortical development by EXOC7 and EXOC8, components of the exocyst complex, and roles in neural progenitor cell proliferation and survival.}, journal = {Genet Med}, volume = {22}, year = {2020}, month = {2020 06}, pages = {1040-1050}, abstract = {

PURPOSE: The exocyst complex is a conserved protein complex that mediates fusion of intracellular vesicles to the plasma membrane and is implicated in processes including cell polarity, cell migration, ciliogenesis, cytokinesis, autophagy, and fusion of secretory vesicles. The essential role of these genes in human genetic disorders, however, is unknown.

METHODS: We performed homozygosity mapping and exome sequencing of consanguineous families with recessively inherited brain development disorders. We modeled an EXOC7 splice variant in vitro and examined EXOC7 messenger RNA (mRNA) expression in developing mouse and human cortex. We modeled exoc7 loss-of-function in a zebrafish knockout.

RESULTS: We report variants in exocyst complex members, EXOC7 and EXOC8, in a novel disorder of cerebral cortex development. In EXOC7, we identified four independent partial loss-of-function (LOF) variants in a recessively inherited disorder characterized by brain atrophy, seizures, and developmental delay, and in severe cases, microcephaly and infantile death. In EXOC8, we found a homozygous truncating variant in a family with a similar clinical disorder. We modeled exoc7 deficiency in zebrafish and found the absence of exoc7 causes microcephaly.

CONCLUSION: Our results highlight the essential role of the exocyst pathway in normal cortical development and how its perturbation causes complex brain disorders.

}, keywords = {Animals, Brain Diseases, Cell Proliferation, Homozygote, Humans, Mice, Microcephaly, Zebrafish}, issn = {1530-0366}, doi = {10.1038/s41436-020-0758-9}, author = {Coulter, Michael E and Musaev, Damir and DeGennaro, Ellen M and Zhang, Xiaochang and Henke, Katrin and James, Kiely N and Smith, Richard S and Hill, R Sean and Partlow, Jennifer N and Kamumbu, A Stacy and Hatem, Nicole and Barkovich, A James and Aziza, Jacqueline and Chassaing, Nicolas and Zaki, MAH S and Sultan, Tipu and Burglen, Lydie and Rajab, Anna and Al-Gazali, Lihadh and Mochida, Ganeshwaran H and Harris, Matthew P and Gleeson, Joseph G and Walsh, Christopher A} } @article {922, title = {Using to drive the diagnosis and understand the mechanisms of rare human diseases.}, journal = {Development}, volume = {147}, year = {2020}, month = {2020 09 28}, abstract = {

Next-generation sequencing has greatly accelerated the discovery of rare human genetic diseases. Nearly 45\% of patients have variants associated with known diseases but the unsolved cases remain a conundrum. Moreover, causative mutations can be difficult to pinpoint because variants frequently map to genes with no previous disease associations and, often, only one or a few patients with variants in the same gene are identified. Model organisms, such as , can help to identify and characterize these new disease-causing genes. Importantly, allow quick and sophisticated genetic manipulations, permit functional testing of human variants, enable the characterization of pathogenic mechanisms and are amenable to drug tests. In this Spotlight, focusing on microcephaly as a case study, we highlight how studies of human genes in have aided our understanding of human genetic disorders, allowing the identification of new genes in well-established signaling pathways.

}, keywords = {Animals, Disease Models, Animal, Drosophila melanogaster, Genetic Techniques, Human Genetics, Humans, Microcephaly, Rare Diseases}, issn = {1477-9129}, doi = {10.1242/dev.191411}, author = {Link, Nichole and Bellen, Hugo J} } @article {574, title = {Biallelic mutations in valyl-tRNA synthetase gene VARS are associated with a progressive neurodevelopmental epileptic encephalopathy.}, journal = {Nat Commun}, volume = {10}, year = {2019}, month = {2019 02 12}, pages = {707}, abstract = {

Aminoacyl-tRNA synthetases (ARSs) function to transfer amino acids to cognate tRNA molecules, which are required for protein translation. To date, biallelic mutations in 31 ARS genes are known to cause recessive, early-onset severe multi-organ diseases. VARS encodes the only known valine cytoplasmic-localized aminoacyl-tRNA synthetase. Here, we report seven patients from five unrelated families with five different biallelic missense variants in VARS. Subjects present with a range of global developmental delay, epileptic encephalopathy and primary or progressive microcephaly. Longitudinal assessment demonstrates progressive cortical atrophy and white matter volume loss. Variants map to the VARS tRNA binding domain and adjacent to the anticodon domain, and disrupt highly conserved residues. Patient primary cells show intact VARS protein but reduced enzymatic activity, suggesting partial loss of function. The implication of VARS in pediatric neurodegeneration broadens the spectrum of human diseases due to mutations in tRNA synthetase genes.

}, keywords = {Alleles, Anticodon, Child, Child, Preschool, Disease Progression, Epilepsy, Female, Genetic Predisposition to Disease, Humans, Longitudinal Studies, Loss of Function Mutation, Male, Microcephaly, Models, Molecular, Mutation, Neurodevelopmental Disorders, Pedigree, Protein Biosynthesis, Protein Interaction Domains and Motifs, RNA, Transfer, Valine-tRNA Ligase, Whole Exome Sequencing, Whole Genome Sequencing}, issn = {2041-1723}, doi = {10.1038/s41467-018-07067-3}, author = {Friedman, Jennifer and Smith, Desiree E and Issa, Mahmoud Y and Stanley, Valentina and Wang, Rengang and Mendes, Marisa I and Wright, Meredith S and Wigby, Kristen and Hildreth, Amber and Crawford, John R and Koehler, Alanna E and Chowdhury, Shimul and Nahas, Shareef and Zhai, Liting and Xu, Zhiwen and Lo, Wing-Sze and James, Kiely N and Musaev, Damir and Accogli, Andrea and Guerrero, Kether and Tran, Luan T and Omar, Tarek E I and Ben-Omran, Tawfeg and Dimmock, David and Kingsmore, Stephen F and Salomons, Gajja S and Zaki, Maha S and Bernard, Genevi{\`e}ve and Gleeson, Joseph G} } @article {573, title = {Biallelic VARS variants cause developmental encephalopathy with microcephaly that is recapitulated in vars knockout zebrafish.}, journal = {Nat Commun}, volume = {10}, year = {2019}, month = {2019 02 12}, pages = {708}, abstract = {

Aminoacyl tRNA synthetases (ARSs) link specific amino acids with their cognate transfer RNAs in a critical early step of protein translation. Mutations in ARSs have emerged as a cause of recessive, often complex neurological disease traits. Here we report an allelic series consisting of seven novel and two previously reported biallelic variants in valyl-tRNA synthetase (VARS) in ten patients with a developmental encephalopathy with microcephaly, often associated with early-onset epilepsy. In silico, in vitro, and yeast complementation assays demonstrate that the underlying pathomechanism of these mutations is most likely a loss of protein function. Zebrafish modeling accurately recapitulated some of the key neurological disease traits. These results provide both genetic and biological insights into neurodevelopmental disease and pave the way for further in-depth research on ARS related recessive disorders and precision therapies.

}, keywords = {Alleles, Animals, Brain Diseases, Cell Line, Disease Models, Animal, Epilepsy, Female, Fibroblasts, Gene Knockout Techniques, Genetic Predisposition to Disease, Humans, Loss of Function Mutation, Male, Microcephaly, Models, Molecular, Neurodevelopmental Disorders, Pedigree, Prosencephalon, Valine-tRNA Ligase, Zebrafish}, issn = {2041-1723}, doi = {10.1038/s41467-018-07953-w}, author = {Siekierska, Aleksandra and Stamberger, Hannah and Deconinck, Tine and Oprescu, Stephanie N and Partoens, Mich{\`e}le and Zhang, Yifan and Sourbron, Jo and Adriaenssens, Elias and Mullen, Patrick and Wiencek, Patrick and Hardies, Katia and Lee, Jeong-Soo and Giong, Hoi-Khoanh and Distelmaier, Felix and Elpeleg, Orly and Helbig, Katherine L and Hersh, Joseph and Isikay, Sedat and Jordan, Elizabeth and Karaca, Ender and Kecskes, Angela and Lupski, James R and Kovacs-Nagy, Reka and May, Patrick and Narayanan, Vinodh and Pendziwiat, Manuela and Ramsey, Keri and Rangasamy, Sampathkumar and Shinde, Deepali N and Spiegel, Ronen and Timmerman, Vincent and von Spiczak, Sarah and Helbig, Ingo and Weckhuysen, Sarah and Francklyn, Christopher and Antonellis, Anthony and de Witte, Peter and De Jonghe, Peter} } @article {452, title = {Biallelic variants in KIF14 cause intellectual disability with microcephaly.}, journal = {Eur J Hum Genet}, volume = {26}, year = {2018}, month = {2018 03}, pages = {330-339}, abstract = {

Kinesin proteins are critical for various cellular functions such as intracellular transport and cell division, and many members of the family have been linked to monogenic disorders and cancer. We report eight individuals with intellectual disability and microcephaly from four unrelated families with parental consanguinity. In the affected individuals of each family, homozygosity for likely pathogenic variants in KIF14 were detected; two loss-of-function (p.Asn83Ilefs*3 and p.Ser1478fs), and two missense substitutions (p.Ser841Phe and p.Gly459Arg). KIF14 is a mitotic motor protein that is required for spindle localization of the mitotic citron rho-interacting kinase, CIT, also mutated in microcephaly. Our results demonstrate the involvement of KIF14 in development and reveal a wide phenotypic variability ranging from fetal lethality to moderate developmental delay and microcephaly.

}, keywords = {Child, Child, Preschool, Female, Humans, Intellectual Disability, Kinesin, Loss of Function Mutation, Microcephaly, Mutation, Missense, Oncogene Proteins, Pedigree, Phenotype, Protein Domains, Syndrome}, issn = {1476-5438}, doi = {10.1038/s41431-017-0088-9}, author = {Makrythanasis, Periklis and Maroofian, Reza and Stray-Pedersen, Asbj{\o}rg and Musaev, Damir and Zaki, Maha S and Mahmoud, Iman G and Selim, Laila and Elbadawy, Amera and Jhangiani, Shalini N and Coban Akdemir, Zeynep H and Gambin, Tomasz and Sorte, Hanne S and Heiberg, Arvid and McEvoy-Venneri, Jennifer and James, Kiely N and Stanley, Valentina and Belandres, Denice and Guipponi, Michel and Santoni, Federico A and Ahangari, Najmeh and Tara, Fatemeh and Doosti, Mohammad and Iwaszkiewicz, Justyna and Zoete, Vincent and Backe, Paul Hoff and Hamamy, Hanan and Gleeson, Joseph G and Lupski, James R and Karimiani, Ehsan Ghayoor and Antonarakis, Stylianos E} } @article {494, title = {A homozygous founder mutation in associates with a neurodevelopmental disorder characterised by microcephaly, epilepsy and autistic features.}, journal = {J Med Genet}, volume = {55}, year = {2018}, month = {2018 01}, pages = {48-54}, abstract = {

BACKGROUND: Transport protein particle (TRAPP) is a multisubunit complex that regulates membrane trafficking through the Golgi apparatus. The clinical phenotype associated with mutations in various TRAPP subunits has allowed elucidation of their functions in specific tissues. The role of some subunits in human disease, however, has not been fully established, and their functions remain uncertain.

OBJECTIVE: We aimed to expand the range of neurodevelopmental disorders associated with mutations in TRAPP subunits by exome sequencing of consanguineous families.

METHODS: Linkage and homozygosity mapping and candidate gene analysis were used to identify homozygous mutations in families. Patient fibroblasts were used to study splicing defect and zebrafish to model the disease.

RESULTS: We identified six individuals from three unrelated families with a founder homozygous splice mutation in , encoding a core subunit of the complex TRAPP I. Patients manifested a neurodevelopmental disorder characterised by microcephaly, epilepsy and autistic features, and showed splicing defect. Zebrafish morphants replicated the human phenotype, displaying decreased head size and neuronal hyperexcitability, leading to a lower seizure threshold.

CONCLUSION: This study provides clinical and functional evidence of the role of in brain development and function.

}, keywords = {Animals, Autistic Disorder, Epilepsy, Founder Effect, Genetic Association Studies, Homozygote, Humans, Microcephaly, Mutation, Neurodevelopmental Disorders, Phenotype, Vesicular Transport Proteins, Zebrafish}, issn = {1468-6244}, doi = {10.1136/jmedgenet-2017-104627}, author = {Marin-Valencia, Isaac and Novarino, Gaia and Johansen, Anide and Rosti, Basak and Issa, Mahmoud Y and Musaev, Damir and Bhat, Gifty and Scott, Eric and Silhavy, Jennifer L and Stanley, Valentina and Rosti, Rasim O and Gleeson, Jeremy W and Imam, Farhad B and Zaki, Maha S and Gleeson, Joseph G} } @article {335, title = {De Novo Disruption of the Proteasome Regulatory Subunit PSMD12 Causes a Syndromic Neurodevelopmental Disorder.}, journal = {Am J Hum Genet}, volume = {100}, year = {2017}, month = {2017 Feb 02}, pages = {352-363}, abstract = {

Degradation of proteins by the ubiquitin-proteasome system (UPS) is an essential biological process in the development of eukaryotic organisms. Dysregulation of this mechanism leads to numerous human neurodegenerative or neurodevelopmental disorders. Through a multi-center collaboration, we identified six de novo genomic deletions and four de novo point mutations involving PSMD12, encoding the non-ATPase subunit PSMD12 (aka RPN5) of the 19S regulator of 26S proteasome complex, in unrelated individuals with intellectual disability, congenital malformations, ophthalmologic anomalies, feeding difficulties, deafness, and subtle dysmorphic facial features. We observed reduced PSMD12 levels and an accumulation of ubiquitinated proteins without any impairment of proteasome catalytic activity. Our PSMD12 loss-of-function zebrafish CRISPR/Cas9 model exhibited microcephaly, decreased convolution of the renal tubules, and abnormal craniofacial morphology. Our data support the biological importance of PSMD12 as a scaffolding subunit in proteasome function during development and neurogenesis in particular; they enable the definition of a neurodevelopmental disorder due to PSMD12 variants, expanding the phenotypic spectrum of UPS-dependent disorders.

}, keywords = {Adolescent, Animals, Child, Child, Preschool, Disease Models, Animal, DNA Copy Number Variations, Down-Regulation, Female, Gene Deletion, Humans, Infant, Intellectual Disability, Male, Microcephaly, Neurodevelopmental Disorders, Polymorphism, Single Nucleotide, Proteasome Endopeptidase Complex, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.01.003}, author = {K{\"u}ry, S{\'e}bastien and Besnard, Thomas and Ebstein, Fr{\'e}d{\'e}ric and Khan, Tahir N and Gambin, Tomasz and Douglas, Jessica and Bacino, Carlos A and Craigen, William J and Sanders, Stephan J and Lehmann, Andrea and Latypova, X{\'e}nia and Khan, Kamal and Pacault, Mathilde and Sacharow, Stephanie and Glaser, Kimberly and Bieth, Eric and Perrin-Sabourin, Laurence and Jacquemont, Marie-Line and Cho, Megan T and Roeder, Elizabeth and Denomm{\'e}-Pichon, Anne-Sophie and Monaghan, Kristin G and Yuan, Bo and Xia, Fan and Simon, Sylvain and Bonneau, Dominique and Parent, Philippe and Gilbert-Dussardier, Brigitte and Odent, Sylvie and Toutain, Annick and Pasquier, Laurent and Barbouth, Deborah and Shaw, Chad A and Patel, Ankita and Smith, Janice L and Bi, Weimin and Schmitt, S{\'e}bastien and Deb, Wallid and Nizon, Mathilde and Mercier, Sandra and Vincent, Marie and Rooryck, Caroline and Malan, Val{\'e}rie and Brice{\~n}o, Ignacio and G{\'o}mez, Alberto and Nugent, Kimberly M and Gibson, James B and Cogn{\'e}, Benjamin and Lupski, James R and Stessman, Holly A F and Eichler, Evan E and Retterer, Kyle and Yang, Yaping and Redon, Richard and Katsanis, Nicholas and Rosenfeld, Jill A and Kloetzel, Peter-Michael and Golzio, Christelle and B{\'e}zieau, St{\'e}phane and Stankiewicz, Pawe{\l} and Isidor, Bertrand} } @article {537, title = {Disruptions in asymmetric centrosome inheritance and WDR62-Aurora kinase B interactions in primary microcephaly.}, journal = {Sci Rep}, volume = {7}, year = {2017}, month = {2017 03 08}, pages = {43708}, abstract = {

Recessive mutations in WD repeat domain 62 (WDR62) cause microcephaly and a wide spectrum of severe brain malformations. Disruption of the mouse ortholog results in microcephaly underlain by reduced proliferation of neocortical progenitors during late neurogenesis, abnormalities in asymmetric centrosome inheritance leading to neuronal migration delays, and altered neuronal differentiation. Spindle pole localization of WDR62 and mitotic progression are defective in patient-derived fibroblasts, which, similar to mouse neocortical progenitors, transiently arrest at prometaphase. Expression of WDR62 is closely correlated with components of the chromosome passenger complex (CPC), a key regulator of mitosis. Wild type WDR62, but not disease-associated mutant forms, interacts with the CPC core enzyme Aurora kinase B and staining of CPC components at centromeres is altered in patient-derived fibroblasts. Our findings demonstrate critical and diverse functions of WDR62 in neocortical development and provide insight into the mechanisms by which its disruption leads to a plethora of structural abnormalities.

}, keywords = {Animals, Aurora Kinase B, Brain, Cell Cycle, Cell Differentiation, Cell Proliferation, Centrosome, Consanguinity, Disease Models, Animal, Epistasis, Genetic, Fluorescent Antibody Technique, Gene Expression, Humans, Inheritance Patterns, Male, Mice, Mice, Knockout, Microcephaly, Mutation, Nerve Tissue Proteins, Neural Stem Cells, Pedigree, Whole Genome Sequencing}, issn = {2045-2322}, doi = {10.1038/srep43708}, author = {Sgourdou, Paraskevi and Mishra-Gorur, Ketu and Saotome, Ichiko and Henagariu, Octavian and Tuysuz, Beyhan and Campos, Cynthia and Ishigame, Keiko and Giannikou, Krinio and Quon, Jennifer L and {\v S}estan, Nenad and {\c C}a{\u g}layan, Ahmet O and G{\"u}nel, Murat and Louvi, Angeliki} } @article {382, title = {Homozygous Mutations in TBC1D23 Lead to a Non-degenerative Form of Pontocerebellar Hypoplasia.}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Sep 07}, pages = {441-450}, abstract = {

Pontocerebellar hypoplasia (PCH) represents a group of recessive developmental disorders characterized by impaired growth of the pons and cerebellum, which frequently follows a degenerative course. Currently, there are 10 partially overlapping clinical subtypes and 13 genes known mutated in PCH. Here, we report biallelic TBC1D23 mutations in six individuals from four unrelated families manifesting a non-degenerative form of PCH. In addition to reduced volume of pons and cerebellum, affected individuals had microcephaly, psychomotor delay, and ataxia. In zebrafish, tbc1d23 morphants replicated the human phenotype showing hindbrain volume loss. TBC1D23 localized at the trans-Golgi and was regulated by the small GTPases Arl1 and Arl8, suggesting a role in trans-Golgi membrane trafficking. Altogether, this study provides a causative link between TBC1D23 mutations and PCH and suggests a less severe clinical course than other PCH subtypes.

}, keywords = {Adolescent, Animals, Cerebellar Diseases, Child, Child, Preschool, Female, GTPase-Activating Proteins, HeLa Cells, Homozygote, Humans, Male, Microcephaly, Mutation, Pedigree, Phenotype, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.07.015}, author = {Marin-Valencia, Isaac and Gerondopoulos, Andreas and Zaki, Maha S and Ben-Omran, Tawfeg and Almureikhi, Mariam and Demir, Ercan and Guemez-Gamboa, Alicia and Gregor, Anne and Issa, Mahmoud Y and Appelhof, Bart and Roosing, Susanne and Musaev, Damir and Rosti, Basak and Wirth, Sara and Stanley, Valentina and Baas, Frank and Barr, Francis A and Gleeson, Joseph G} } @article {359, title = {Kaufman oculo-cerebro-facial syndrome in a child with small and absent terminal phalanges and absent nails.}, journal = {J Hum Genet}, volume = {62}, year = {2017}, month = {2017 Apr}, pages = {465-471}, abstract = {

Kaufman oculo-cerebro-facial syndrome (KOS) is caused by recessive UBE3B mutations and presents with microcephaly, ocular abnormalities, distinctive facial morphology, low cholesterol levels and intellectual disability. We describe a child with microcephaly, brachycephaly, hearing loss, ptosis, blepharophimosis, hypertelorism, cleft palate, multiple renal cysts, absent nails, small or absent terminal phalanges, absent speech and intellectual disability. Syndromes that were initially considered include DOORS syndrome, Coffin-Siris syndrome and Dubowitz syndrome. Clinical investigations coupled with karyotype analysis, array-comparative genomic hybridization, exome and Sanger sequencing were performed to characterize the condition in this child. Sanger sequencing was negative for the DOORS syndrome gene TBC1D24 but exome sequencing identified a homozygous deletion in UBE3B (NM_183415:c.3139_3141del, p.1047_1047del) located within the terminal portion of the HECT domain. This finding coupled with the presence of characteristic features such as brachycephaly, ptosis, blepharophimosis, hypertelorism, short palpebral fissures, cleft palate and developmental delay allowed us to make a diagnosis of KOS. In conclusion, our findings highlight the importance of considering KOS as a differential diagnosis for patients under evaluation for DOORS syndrome and expand the phenotype of KOS to include small or absent terminal phalanges, nails, and the presence of hallux varus and multicystic dysplastic kidneys.

}, keywords = {Abnormalities, Multiple, Adult, Carrier Proteins, Child, Child, Preschool, Diagnosis, Differential, Eczema, Eye Abnormalities, Face, Facies, Female, Growth Disorders, Hand Deformities, Congenital, Humans, Intellectual Disability, Karyotype, Limb Deformities, Congenital, Male, Microcephaly, Micrognathism, Mutation, Neck, Pathology, Molecular, Sequence Analysis, DNA, Ubiquitin-Protein Ligases}, issn = {1435-232X}, doi = {10.1038/jhg.2016.151}, author = {Kariminejad, Ariana and Ajeawung, Norbert Fonya and Bozorgmehr, Bita and Dionne-Laporte, Alexandre and Molidperee, Sirinart and Najafi, Kimia and Gibbs, Richard A and Lee, Brendan H and Hennekam, Raoul C and Campeau, Philippe M} } @article {634, title = {Mutations in KEOPS-complex genes cause nephrotic syndrome with primary microcephaly.}, journal = {Nat Genet}, volume = {49}, year = {2017}, month = {2017 Oct}, pages = {1529-1538}, abstract = {

Galloway-Mowat syndrome (GAMOS) is an autosomal-recessive disease characterized by the combination of early-onset nephrotic syndrome (SRNS) and microcephaly with brain anomalies. Here we identified recessive mutations in OSGEP, TP53RK, TPRKB, and LAGE3, genes encoding the four subunits of the KEOPS complex, in 37 individuals from 32 families with GAMOS. CRISPR-Cas9 knockout in zebrafish and mice recapitulated the human phenotype of primary microcephaly and resulted in early lethality. Knockdown of OSGEP, TP53RK, or TPRKB inhibited cell proliferation, which human mutations did not rescue. Furthermore, knockdown of these genes impaired protein translation, caused endoplasmic reticulum stress, activated DNA-damage-response signaling, and ultimately induced apoptosis. Knockdown of OSGEP or TP53RK induced defects in the actin cytoskeleton and decreased the migration rate of human podocytes, an established intermediate phenotype of SRNS. We thus identified four new monogenic causes of GAMOS, describe a link between KEOPS function and human disease, and delineate potential pathogenic mechanisms.

}, keywords = {Animals, Apoptosis, Carrier Proteins, Cell Movement, CRISPR-Cas Systems, Cytoskeleton, DNA Repair, Endoplasmic Reticulum Stress, Gene Knockout Techniques, Hernia, Hiatal, Humans, Intracellular Signaling Peptides and Proteins, Metalloendopeptidases, Mice, Microcephaly, Models, Molecular, Multiprotein Complexes, Mutation, Nephrosis, Nephrotic Syndrome, Podocytes, Protein Conformation, Protein-Serine-Threonine Kinases, RNA Processing, Post-Transcriptional, RNA, Transfer, Telomere Homeostasis, Zebrafish, Zebrafish Proteins}, issn = {1546-1718}, doi = {10.1038/ng.3933}, author = {Braun, Daniela A and Rao, Jia and Mollet, Geraldine and Schapiro, David and Daugeron, Marie-Claire and Tan, Weizhen and Gribouval, Olivier and Boyer, Olivia and Revy, Patrick and Jobst-Schwan, Tilman and Schmidt, Johanna Magdalena and Lawson, Jennifer A and Schanze, Denny and Ashraf, Shazia and Ullmann, Jeremy F P and Hoogstraten, Charlotte A and Boddaert, Nathalie and Collinet, Bruno and Martin, Ga{\"e}lle and Liger, Dominique and Lovric, Svjetlana and Furlano, Monica and Guerrera, I Chiara and Sanchez-Ferras, Oraly and Hu, Jennifer F and Boschat, Anne-Claire and Sanquer, Sylvia and Menten, Bj{\"o}rn and Vergult, Sarah and De Rocker, Nina and Airik, Merlin and Hermle, Tobias and Shril, Shirlee and Widmeier, Eugen and Gee, Heon Yung and Choi, Won-Il and Sadowski, Carolin E and Pabst, Werner L and Warejko, Jillian K and Daga, Ankana and Basta, Tamara and Matejas, Verena and Scharmann, Karin and Kienast, Sandra D and Behnam, Babak and Beeson, Brendan and Begtrup, Amber and Bruce, Malcolm and Ch{\textquoteright}ng, Gaik-Siew and Lin, Shuan-Pei and Chang, Jui-Hsing and Chen, Chao-Huei and Cho, Megan T and Gaffney, Patrick M and Gipson, Patrick E and Hsu, Chyong-Hsin and Kari, Jameela A and Ke, Yu-Yuan and Kiraly-Borri, Cathy and Lai, Wai-Ming and Lemyre, Emmanuelle and Littlejohn, Rebecca Okashah and Masri, Amira and Moghtaderi, Mastaneh and Nakamura, Kazuyuki and Ozaltin, Fatih and Praet, Marleen and Prasad, Chitra and Prytula, Agnieszka and Roeder, Elizabeth R and Rump, Patrick and Schnur, Rhonda E and Shiihara, Takashi and Sinha, Manish D and Soliman, Neveen A and Soulami, Kenza and Sweetser, David A and Tsai, Wen-Hui and Tsai, Jeng-Daw and Topaloglu, Rezan and Vester, Udo and Viskochil, David H and Vatanavicharn, Nithiwat and Waxler, Jessica L and Wierenga, Klaas J and Wolf, Matthias T F and Wong, Sik-Nin and Leidel, Sebastian A and Truglio, Gessica and Dedon, Peter C and Poduri, Annapurna and Mane, Shrikant and Lifton, Richard P and Bouchard, Maxime and Kannu, Peter and Chitayat, David and Magen, Daniella and Callewaert, Bert and van Tilbeurgh, Herman and Zenker, Martin and Antignac, Corinne and Hildebrandt, Friedhelm} } @article {396, title = {A novel mutation in GMPPA in siblings with apparent intellectual disability, epilepsy, dysmorphism, and autonomic dysfunction.}, journal = {Am J Med Genet A}, volume = {173}, year = {2017}, month = {2017 Aug}, pages = {2246-2250}, abstract = {

GMPPA encodes the GDP-mannose pyrophosphorylase A protein (GMPPA). The function of GMPPA is not well defined, however it is a homolog of GMPPB which catalyzes the reaction that converts mannose-1-phosphate and guanosine-5{\textquoteright}-triphosphate to GDP-mannose. Previously, biallelic mutations in GMPPA were reported to cause a disorder characterized by achalasia, alacrima, neurological deficits, and intellectual disability. In this study, we report a female proband with achalasia, alacrima, hypohydrosis, apparent intellectual disability, seizures, microcephaly, esotropia, and craniofacial dysmorphism. Exome sequencing identified a previously unreported homozygous c.853+1G>A variant in GMPPA in the proband and her affected sister. Their unaffected parents were heterozygous, and unaffected brother homozygous wild type for this variant. Lymphoblast cells from the affected sisters showed complete loss of the GMPPA protein by Western blotting, and increased levels of GDP-mannose in lymphoblasts on high performance liquid chromatography. Based on our findings and the previous report describing patients with an overlapping phenotype, we conclude that this novel variant in GMPPA, identified by exome sequencing in the proband and her affected sister, is the genetic cause of their phenotype and may expand the known phenotype of this recently described glycosylation disorder.

}, keywords = {Abnormalities, Multiple, Child, Child, Preschool, Craniofacial Abnormalities, Epilepsy, Exome, Facies, Female, Heterozygote, Humans, Intellectual Disability, Microcephaly, Muscular Atrophy, Mutation, Missense, Nucleotidyltransferases, Pedigree, Phenotype, Seizures}, issn = {1552-4833}, doi = {10.1002/ajmg.a.38292}, author = {Gold, Wendy A and Sobreira, Nara and Wiame, Elsa and Marbaix, Alexandre and Van Schaftingen, Emile and Franzka, Patricia and Riley, Lisa G and Worgan, Lisa and H{\"u}bner, Christian A and Christodoulou, John and Ad{\`e}s, Lesley C} } @article {355, title = {PRUNE is crucial for normal brain development and mutated in microcephaly with neurodevelopmental impairment.}, journal = {Brain}, volume = {140}, year = {2017}, month = {2017 Apr 01}, pages = {940-952}, abstract = {

PRUNE is a member of the DHH (Asp-His-His) phosphoesterase protein superfamily of molecules important for cell motility, and implicated in cancer progression. Here we investigated multiple families from Oman, India, Iran and Italy with individuals affected by a new autosomal recessive neurodevelopmental and degenerative disorder in which the cardinal features include primary microcephaly and profound global developmental delay. Our genetic studies identified biallelic mutations of PRUNE1 as responsible. Our functional assays of disease-associated variant alleles revealed impaired microtubule polymerization, as well as cell migration and proliferation properties, of mutant PRUNE. Additionally, our studies also highlight a potential new role for PRUNE during microtubule polymerization, which is essential for the cytoskeletal rearrangements that occur during cellular division and proliferation. Together these studies define PRUNE as a molecule fundamental for normal human cortical development and define cellular and clinical consequences associated with PRUNE mutation.

}, keywords = {Adolescent, Brain, Carrier Proteins, Cell Differentiation, Cell Movement, Cerebral Cortex, Child, Child, Preschool, Cytoskeleton, Developmental Disabilities, Female, Genes, Recessive, Heredodegenerative Disorders, Nervous System, Humans, Infant, Male, Microcephaly, Microtubules, Mutation, Pedigree, Young Adult}, issn = {1460-2156}, doi = {10.1093/brain/awx014}, author = {Zollo, Massimo and Ahmed, Mustafa and Ferrucci, Veronica and Salpietro, Vincenzo and Asadzadeh, Fatemeh and Carotenuto, Marianeve and Maroofian, Reza and Al-Amri, Ahmed and Singh, Royana and Scognamiglio, Iolanda and Mojarrad, Majid and Musella, Luca and Duilio, Angela and Di Somma, Angela and Karaca, Ender and Rajab, Anna and Al-Khayat, Aisha and Mohan Mohapatra, Tribhuvan and Eslahi, Atieh and Ashrafzadeh, Farah and Rawlins, Lettie E and Prasad, Rajniti and Gupta, Rashmi and Kumari, Preeti and Srivastava, Mona and Cozzolino, Flora and Kumar Rai, Sunil and Monti, Maria and Harlalka, Gaurav V and Simpson, Michael A and Rich, Philip and Al-Salmi, Fatema and Patton, Michael A and Chioza, Barry A and Efthymiou, Stephanie and Granata, Francesca and Di Rosa, Gabriella and Wiethoff, Sarah and Borgione, Eugenia and Scuderi, Carmela and Mankad, Kshitij and Hanna, Michael G and Pucci, Piero and Houlden, Henry and Lupski, James R and Crosby, Andrew H and Baple, Emma L} } @article {334, title = {A Recurrent De Novo Variant in NACC1 Causes a Syndrome Characterized by Infantile Epilepsy, Cataracts, and Profound Developmental Delay.}, journal = {Am J Hum Genet}, volume = {100}, year = {2017}, month = {2017 Feb 02}, pages = {343-351}, abstract = {

Whole-exome sequencing (WES) has increasingly enabled new pathogenic gene variant identification for undiagnosed neurodevelopmental disorders and provided insights into both gene function and disease biology. Here, we describe seven children with a neurodevelopmental disorder characterized by microcephaly, profound developmental delays and/or intellectual disability, cataracts, severe epilepsy including infantile spasms, irritability, failure to thrive, and stereotypic hand movements. Brain imaging in these individuals reveals delay in myelination and cerebral atrophy. We observe an identical recurrent de novo heterozygous c.892C>T (p.Arg298Trp) variant in the nucleus accumbens associated 1 (NACC1) gene in seven affected individuals. One of the seven individuals is mosaic for this variant. NACC1 encodes a transcriptional repressor implicated in gene expression and has not previously been associated with germline disorders. The probability of finding the same missense NACC1 variant by chance in 7 out of 17,228 individuals who~underwent WES for diagnoses of neurodevelopmental phenotypes is extremely small and achieves genome-wide significance (p~= 1.25~{\texttimes} 10). Selective constraint against missense variants in NACC1 makes this excess of an identical missense variant in all seven individuals more remarkable. Our findings are consistent with a germline recurrent mutational hotspot associated with an allele-specific neurodevelopmental phenotype in NACC1.

}, keywords = {Alleles, Amino Acid Sequence, Brain, Cataract, Child, Child, Preschool, Female, Genetic Variation, Genome-Wide Association Study, Humans, Infant, Intellectual Disability, Magnetic Resonance Imaging, Male, Microcephaly, Mutation, Missense, Neoplasm Proteins, Pedigree, Phenotype, Repressor Proteins, Spasms, Infantile}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.12.013}, author = {Schoch, Kelly and Meng, Linyan and Szelinger, Szabolcs and Bearden, David R and Stray-Pedersen, Asbjorg and Busk, Oyvind L and Stong, Nicholas and Liston, Eriskay and Cohn, Ronald D and Scaglia, Fernando and Rosenfeld, Jill A and Tarpinian, Jennifer and Skraban, Cara M and Deardorff, Matthew A and Friedman, Jeremy N and Akdemir, Zeynep Coban and Walley, Nicole and Mikati, Mohamad A and Kranz, Peter G and Jasien, Joan and McConkie-Rosell, Allyn and McDonald, Marie and Wechsler, Stephanie Burns and Freemark, Michael and Kansagra, Sujay and Freedman, Sharon and Bali, Deeksha and Millan, Francisca and Bale, Sherri and Nelson, Stanley F and Lee, Hane and Dorrani, Naghmeh and Goldstein, David B and Xiao, Rui and Yang, Yaping and Posey, Jennifer E and Martinez-Agosto, Julian A and Lupski, James R and Wangler, Michael F and Shashi, Vandana} } @article {37, title = {Biallelic Mutations in Citron Kinase Link Mitotic Cytokinesis to Human Primary Microcephaly.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Aug 04}, pages = {501-10}, abstract = {

Cell division terminates with cytokinesis and cellular separation. Autosomal-recessive primary microcephaly (MCPH) is a neurodevelopmental disorder characterized by a reduction in brain and head size at birth in addition to non-progressive intellectual disability. MCPH is genetically heterogeneous, and 16 loci are known to be associated with loss-of-function mutations predominantly affecting centrosomal-associated proteins, but the multiple roles of centrosomes in cellular function has left questions about etiology. Here, we identified three families affected by homozygous missense mutations in CIT, encoding citron rho-interacting kinase (CIT), which has established roles in cytokinesis. All mutations caused substitution of conserved amino acid residues in the kinase domain and impaired kinase activity. Neural progenitors that were differentiated from induced pluripotent stem cells (iPSCs) derived from individuals with these mutations exhibited abnormal cytokinesis with delayed mitosis, multipolar spindles, and increased apoptosis, rescued by CRISPR/Cas9 genome editing. Our results highlight the importance of cytokinesis in the pathology of primary microcephaly.

}, keywords = {Alleles, Apoptosis, Centrosome, Child, Child, Preschool, Cytokinesis, Female, Genes, Recessive, Humans, Infant, Newborn, Intracellular Signaling Peptides and Proteins, Male, Microcephaly, Mitosis, Mutation, Missense, Pedigree, Protein Serine-Threonine Kinases}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.07.004}, author = {Li, Hongda and Bielas, Stephanie L and Zaki, Maha S and Ismail, Samira and Farfara, Dorit and Um, Kyongmi and Rosti, Rasim O and Scott, Eric C and Tu, Shu and Chi, Neil C and Gabriel, Stacey and Erson-Omay, Emine Z and Ercan-Sencicek, A Gulhan and Yasuno, Katsuhito and {\c C}a{\u g}layan, Ahmet Okay and Kaymak{\c c}alan, Hande and Ekici, Bar{\i}{\c s} and Bilguvar, Kaya and G{\"u}nel, Murat and Gleeson, Joseph G} } @article {63, title = {PYCR2 Mutations cause a lethal syndrome of microcephaly and failure to thrive.}, journal = {Ann Neurol}, volume = {80}, year = {2016}, month = {2016 07}, pages = {59-70}, abstract = {

OBJECTIVE: A study was undertaken to characterize the clinical features of the newly described hypomyelinating leukodystrophy type 10 with microcephaly. This is an autosomal recessive disorder mapped to chromosome 1q42.12 due to mutations in the PYCR2 gene, encoding an enzyme involved in proline synthesis in mitochondria.

METHODS: From several international clinics, 11 consanguineous families were identified with PYCR2 mutations by whole exome or targeted sequencing, with detailed clinical and radiological phenotyping. Selective mutations from patients were tested for effect on protein function.

RESULTS: The characteristic clinical presentation of patients with PYCR2 mutations included failure to thrive, microcephaly, craniofacial dysmorphism, progressive psychomotor disability, hyperkinetic movements, and axial hypotonia with variable appendicular spasticity. Patients did not survive beyond the first decade of life. Brain magnetic resonance imaging showed global brain atrophy and white matter T2 hyperintensities. Routine serum metabolic profiles were unremarkable. Both nonsense and missense mutations were identified, which impaired protein multimerization.

INTERPRETATION: PYCR2-related syndrome represents a clinically recognizable condition in which PYCR2 mutations lead to protein dysfunction, not detectable on routine biochemical assessments. Mutations predict a poor outcome, probably as a result of impaired mitochondrial function. Ann Neurol 2016;80:59-70.

}, keywords = {Adolescent, Child, Child, Preschool, Codon, Nonsense, Exome, Failure to Thrive, Female, Fibroblasts, Gene Expression, Genetic Predisposition to Disease, Genotype, Humans, Infant, Male, Microcephaly, Mutation, Missense, Phenotype, Primary Cell Culture, Pyrroline Carboxylate Reductases, Syndrome, Transfection, Young Adult}, issn = {1531-8249}, doi = {10.1002/ana.24678}, author = {Zaki, Maha S and Bhat, Gifty and Sultan, Tipu and Issa, Mahmoud and Jung, Hea-Jin and Dikoglu, Esra and Selim, Laila and G Mahmoud, Imam and Abdel-Hamid, Mohamed S and Abdel-Salam, Ghada and Marin-Valencia, Isaac and Gleeson, Joseph G} } @article {161, title = {Inactivating mutations in MFSD2A, required for omega-3 fatty acid transport in brain, cause a lethal microcephaly syndrome.}, journal = {Nat Genet}, volume = {47}, year = {2015}, month = {2015 Jul}, pages = {809-13}, abstract = {

Docosahexanoic acid (DHA) is the most abundant omega-3 fatty acid in brain, and, although it is considered essential, deficiency has not been linked to disease. Despite the large mass of DHA in phospholipids, the brain does not synthesize it. DHA is imported across the blood-brain barrier (BBB) through the major facilitator superfamily domain-containing 2a (MFSD2A) protein. MFSD2A transports DHA as well as other fatty acids in the form of lysophosphatidylcholine (LPC). We identify two families displaying MFSD2A mutations in conserved residues. Affected individuals exhibited a lethal microcephaly syndrome linked to inadequate uptake of LPC lipids. The MFSD2A mutations impaired transport activity in a cell-based assay. Moreover, when expressed in mfsd2aa-morphant zebrafish, mutants failed to rescue microcephaly, BBB breakdown and lethality. Our results establish a link between transport of DHA and LPCs by MFSD2A and human brain growth and function, presenting the first evidence of monogenic disease related to transport of DHA in humans.

}, keywords = {Adolescent, Animals, Biological Transport, Blood-Brain Barrier, Brain, Case-Control Studies, Child, Child, Preschool, Consanguinity, Fatty Acids, Omega-3, Female, Genes, Lethal, Genetic Association Studies, HEK293 Cells, Humans, Infant, Male, Mice, Knockout, Microcephaly, Mutation, Missense, Syndrome, Tumor Suppressor Proteins, Zebrafish}, issn = {1546-1718}, doi = {10.1038/ng.3311}, author = {Guemez-Gamboa, Alicia and Nguyen, Long N and Yang, Hongbo and Zaki, Maha S and Kara, Majdi and Ben-Omran, Tawfeg and Akizu, Naiara and Rosti, Rasim Ozgur and Rosti, Basak and Scott, Eric and Schroth, Jana and Copeland, Brett and Vaux, Keith K and Cazenave-Gassiot, Amaury and Quek, Debra Q Y and Wong, Bernice H and Tan, Bryan C and Wenk, Markus R and G{\"u}nel, Murat and Gabriel, Stacey and Chi, Neil C and Silver, David L and Gleeson, Joseph G} } @article {130, title = {Mutations in SPATA5 Are Associated with Microcephaly, Intellectual Disability, Seizures, and Hearing Loss.}, journal = {Am J Hum Genet}, volume = {97}, year = {2015}, month = {2015 Sep 03}, pages = {457-64}, abstract = {

Using whole-exome sequencing, we have identified in ten families 14 individuals with microcephaly, developmental delay, intellectual disability, hypotonia, spasticity, seizures, sensorineural hearing loss, cortical visual impairment, and rare autosomal-recessive predicted pathogenic variants in spermatogenesis-associated protein 5 (SPATA5). SPATA5 encodes a ubiquitously expressed member of the ATPase associated with diverse activities (AAA) protein family and is involved in mitochondrial morphogenesis during early spermatogenesis. It might also play a role in post-translational modification during cell differentiation in neuronal development. Mutations in SPATA5 might affect brain development and function, resulting in microcephaly, developmental delay, and intellectual disability.

}, keywords = {Abnormalities, Multiple, Amino Acid Sequence, ATPases Associated with Diverse Cellular Activities, Base Sequence, Exome, Female, Gene Frequency, Genes, Recessive, Hearing Loss, Homeodomain Proteins, Humans, Intellectual Disability, Male, Microcephaly, Molecular Sequence Data, Mutation, Seizures, Sequence Alignment, Sequence Analysis, DNA}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2015.07.014}, author = {Tanaka, Akemi J and Cho, Megan T and Millan, Francisca and Juusola, Jane and Retterer, Kyle and Joshi, Charuta and Niyazov, Dmitriy and Garnica, Adolfo and Gratz, Edward and Deardorff, Matthew and Wilkins, Alisha and Ortiz-Gonzalez, Xilma and Mathews, Katherine and Panzer, Karin and Brilstra, Eva and van Gassen, Koen L I and Volker-Touw, Catharina M L and van Binsbergen, Ellen and Sobreira, Nara and Hamosh, Ada and McKnight, Dianalee and Monaghan, Kristin G and Chung, Wendy K} } @article {209, title = {Dosage changes of a segment at 17p13.1 lead to intellectual disability and microcephaly as a result of complex genetic interaction of multiple genes.}, journal = {Am J Hum Genet}, volume = {95}, year = {2014}, month = {2014 Nov 06}, pages = {565-78}, abstract = {

The 17p13.1 microdeletion syndrome is a recently described genomic disorder with a core clinical phenotype of intellectual disability, poor to absent speech, dysmorphic features, and a constellation of more variable clinical features, most prominently microcephaly. We identified five subjects with copy-number variants (CNVs) on 17p13.1 for whom we performed detailed clinical and molecular studies. Breakpoint mapping and retrospective analysis of published cases refined the smallest region of overlap (SRO) for microcephaly to a genomic interval containing nine genes. Dissection of this phenotype in zebrafish embryos revealed a complex genetic architecture: dosage perturbation of four genes (ASGR1, ACADVL, DVL2, and GABARAP) impeded neurodevelopment and decreased dosage of the same loci caused a reduced mitotic index in~vitro. Moreover, epistatic analyses in~vivo showed that dosage perturbations of discrete gene pairings induce microcephaly. Taken together, these studies support a model in which concomitant dosage perturbation of multiple genes within the CNV drive the microcephaly and possibly other neurodevelopmental phenotypes associated with rearrangements in the 17p13.1 SRO.

}, keywords = {Abnormalities, Multiple, Acyl-CoA Dehydrogenase, Long-Chain, Adaptor Proteins, Signal Transducing, Animals, Asialoglycoprotein Receptor, Base Sequence, Cell Line, Chromosome Breakpoints, Chromosome Deletion, Chromosomes, Human, Pair 17, Dishevelled Proteins, Flow Cytometry, Gene Dosage, Humans, Immunohistochemistry, Intellectual Disability, Microcephaly, Microtubule-Associated Proteins, Molecular Sequence Data, Phosphoproteins, Retrospective Studies, Sequence Analysis, DNA, Smith-Magenis Syndrome, Syndrome, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2014.10.006}, author = {Carvalho, Claudia M B and Vasanth, Shivakumar and Shinawi, Marwan and Russell, Chad and Ramocki, Melissa B and Brown, Chester W and Graakjaer, Jesper and Skytte, Anne-Bine and Vianna-Morgante, Angela M and Krepischi, Ana C V and Patel, Gayle S and Immken, LaDonna and Aleck, Kyrieckos and Lim, Cynthia and Cheung, Sau Wai and Rosenberg, Carla and Katsanis, Nicholas and Lupski, James R} } @article {253, title = {Human CLP1 mutations alter tRNA biogenesis, affecting both peripheral and central nervous system function.}, journal = {Cell}, volume = {157}, year = {2014}, month = {2014 Apr 24}, pages = {636-50}, abstract = {

CLP1 is a RNA kinase involved in tRNA splicing. Recently, CLP1 kinase-dead mice were shown to display a neuromuscular disorder with loss of motor neurons and muscle paralysis. Human genome analyses now identified a CLP1 homozygous missense mutation (p.R140H) in five unrelated families, leading to a loss of CLP1 interaction with the tRNA splicing endonuclease (TSEN) complex, largely reduced pre-tRNA cleavage activity, and accumulation of linear tRNA introns. The affected individuals develop severe motor-sensory defects, cortical dysgenesis, and microcephaly. Mice carrying kinase-dead CLP1 also displayed microcephaly and reduced cortical brain volume due to the enhanced cell death of neuronal progenitors that is associated with reduced numbers of cortical neurons. Our data elucidate a neurological syndrome defined by CLP1 mutations that impair tRNA splicing. Reduction of a founder mutation to homozygosity illustrates the importance of rare variations in disease and supports the clan genomics hypothesis.

}, keywords = {Abnormalities, Multiple, Animals, Central Nervous System Diseases, Cerebrum, Child, Preschool, Endoribonucleases, Female, Fibroblasts, Humans, Infant, Male, Mice, Mice, Inbred CBA, Microcephaly, Mutation, Missense, Nuclear Proteins, Peripheral Nervous System Diseases, Phosphotransferases, RNA, Transfer, Transcription Factors}, issn = {1097-4172}, doi = {10.1016/j.cell.2014.02.058}, author = {Karaca, Ender and Weitzer, Stefan and Pehlivan, Davut and Shiraishi, Hiroshi and Gogakos, Tasos and Hanada, Toshikatsu and Jhangiani, Shalini N and Wiszniewski, Wojciech and Withers, Marjorie and Campbell, Ian M and Erdin, Serkan and Isikay, Sedat and Franco, Luis M and Gonzaga-Jauregui, Claudia and Gambin, Tomasz and Gelowani, Violet and Hunter, Jill V and Yesil, G{\"o}zde and Koparir, Erkan and Yilmaz, Sarenur and Brown, Miguel and Briskin, Daniel and Hafner, Markus and Morozov, Pavel and Farazi, Thalia A and Bernreuther, Christian and Glatzel, Markus and Trattnig, Siegfried and Friske, Joachim and Kronnerwetter, Claudia and Bainbridge, Matthew N and Gezdirici, Alper and Seven, Mehmet and Muzny, Donna M and Boerwinkle, Eric and Ozen, Mustafa and Clausen, Tim and Tuschl, Thomas and Yuksel, Adnan and Hess, Andreas and Gibbs, Richard A and Martinez, Javier and Penninger, Josef M and Lupski, James R} } @article {284, title = {Microcephaly, epilepsy, and neonatal diabetes due to compound heterozygous mutations in IER3IP1: insights into the natural history of a rare disorder.}, journal = {Pediatr Diabetes}, volume = {15}, year = {2014}, month = {2014 May}, pages = {252-6}, abstract = {

Neonatal diabetes mellitus is known to have over 20 different monogenic causes. A syndrome of permanent neonatal diabetes along with primary microcephaly with simplified gyral pattern associated with severe infantile epileptic encephalopathy was recently described in two independent reports in which disease-causing homozygous mutations were identified in the immediate early response-3 interacting protein-1 (IER3IP1) gene. We report here an affected male born to a non-consanguineous couple who was noted to have insulin-requiring permanent neonatal diabetes, microcephaly, and generalized seizures. He was also found to have cortical blindness, severe developmental delay and numerous dysmorphic features. He experienced a slow improvement but not abrogation of seizure frequency and severity on numerous anti-epileptic agents. His clinical course was further complicated by recurrent respiratory tract infections and he died at 8 years of age. Whole exome sequencing was performed on DNA from the proband and parents. He was found to be a compound heterozygote with two different mutations in IER3IP1: p.Val21Gly (V21G) and a novel frameshift mutation p.Phe27fsSer*25. IER3IP1 is a highly conserved protein with marked expression in the cerebral cortex and in beta cells. This is the first reported case of compound heterozygous mutations within IER3IP1 resulting in neonatal diabetes. The triad of microcephaly, generalized seizures, and permanent neonatal diabetes should prompt screening for mutations in IER3IP1. As mutations in genes such as NEUROD1 and PTF1A could cause a similar phenotype, next-generation sequencing approaches-such as exome sequencing reported here-may be an efficient means of uncovering a diagnosis in future cases.

}, keywords = {Amino Acid Substitution, Blindness, Cortical, Carrier Proteins, Developmental Disabilities, Diabetes Mellitus, Epilepsy, Generalized, Fatal Outcome, Frameshift Mutation, Heterozygote, Humans, Infant, Newborn, Infant, Newborn, Diseases, Male, Membrane Proteins, Microcephaly, Neurologic Manifestations, Point Mutation, Severity of Illness Index}, issn = {1399-5448}, doi = {10.1111/pedi.12086}, author = {Shalev, Stavit A and Tenenbaum-Rakover, Yardena and Horovitz, Yoseph and Paz, Veronica P and Ye, Honggang and Carmody, David and Highland, Heather M and Boerwinkle, Eric and Hanis, Craig L and Muzny, Donna M and Gibbs, Richard A and Bell, Graeme I and Philipson, Louis H and Greeley, Siri Atma W} } @article {243, title = {Monoallelic and biallelic mutations in MAB21L2 cause a spectrum of major eye malformations.}, journal = {Am J Hum Genet}, volume = {94}, year = {2014}, month = {2014 Jun 05}, pages = {915-23}, abstract = {

We identified four different missense mutations in the single-exon gene MAB21L2 in eight individuals with bilateral eye malformations from five unrelated families via three independent exome sequencing projects. Three mutational events altered the same amino acid (Arg51), and two were identical de novo mutations (c.151C>T [p.Arg51Cys]) in unrelated children with bilateral anophthalmia, intellectual disability, and rhizomelic skeletal dysplasia. c.152G>A (p.Arg51His) segregated with autosomal-dominant bilateral colobomatous microphthalmia in a large multiplex family. The fourth heterozygous mutation (c.145G>A [p.Glu49Lys]) affected an amino acid within two residues of Arg51 in an adult male with bilateral colobomata. In a fifth family, a homozygous mutation (c.740G>A [p.Arg247Gln]) altering a different region of the protein was identified in two male siblings with bilateral retinal colobomata. In mouse embryos, Mab21l2 showed strong expression in the developing eye, pharyngeal arches, and limb bud. As predicted by structural homology, wild-type MAB21L2 bound single-stranded RNA, whereas this activity was lost in all altered forms of the protein. MAB21L2 had no detectable nucleotidyltransferase activity in~vitro, and its function remains unknown. Induced expression of wild-type MAB21L2 in human embryonic kidney 293 cells increased phospho-ERK (pERK1/2) signaling. Compared to the wild-type and p.Arg247Gln proteins, the proteins with the Glu49 and Arg51 variants had increased stability. Abnormal persistence of pERK1/2 signaling in MAB21L2-expressing cells during development is a plausible pathogenic mechanism for the heterozygous mutations. The phenotype associated with the homozygous mutation might be a consequence of complete loss of MAB21L2 RNA binding, although the cellular function of this interaction remains unknown.

}, keywords = {Adult, Alleles, Animals, Anophthalmos, Brain Diseases, Metabolic, Inborn, Coloboma, Corneal Opacity, Exome, Eye Proteins, Female, Gene Expression, HEK293 Cells, Heterozygote, Homozygote, Humans, Intellectual Disability, Intracellular Signaling Peptides and Proteins, Male, Mice, Microcephaly, Microphthalmos, Mutation, Missense, Pedigree, Phenotype, Protein Conformation, Signal Transduction}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2014.05.005}, author = {Rainger, Joe and Pehlivan, Davut and Johansson, Stefan and Bengani, Hemant and Sanchez-Pulido, Luis and Williamson, Kathleen A and Ture, Mehmet and Barker, Heather and Rosendahl, Karen and Spranger, J{\"u}rgen and Horn, Denise and Meynert, Alison and Floyd, James A B and Prescott, Trine and Anderson, Carl A and Rainger, Jacqueline K and Karaca, Ender and Gonzaga-Jauregui, Claudia and Jhangiani, Shalini and Muzny, Donna M and Seawright, Anne and Soares, Dinesh C and Kharbanda, Mira and Murday, Victoria and Finch, Andrew and Gibbs, Richard A and van Heyningen, Veronica and Taylor, Martin S and Yakut, Tahsin and Knappskog, Per M and Hurles, Matthew E and Ponting, Chris P and Lupski, James R and Houge, Gunnar and FitzPatrick, David R} } @article {203, title = {Mutations in KATNB1 cause complex cerebral malformations by disrupting asymmetrically dividing neural progenitors.}, journal = {Neuron}, volume = {84}, year = {2014}, month = {2014 Dec 17}, pages = {1226-39}, abstract = {

Exome sequencing analysis of over 2,000 children with complex malformations of cortical development identified five independent (four homozygous and one compound heterozygous) deleterious mutations in KATNB1, encoding the regulatory subunit of the microtubule-severing enzyme Katanin. Mitotic spindle formation is defective in patient-derived fibroblasts, a consequence of disrupted interactions of mutant KATNB1 with KATNA1, the catalytic subunit of Katanin, and other microtubule-associated proteins. Loss of KATNB1 orthologs in zebrafish (katnb1) and flies (kat80) results in microcephaly, recapitulating the human phenotype. In the developing Drosophila optic lobe, kat80 loss specifically affects the asymmetrically dividing neuroblasts, which display supernumerary centrosomes and spindle abnormalities during mitosis, leading to cell cycle progression delays and reduced cell numbers. Furthermore, kat80 depletion results in dendritic arborization defects in sensory and motor neurons, affecting neural architecture. Taken together, we provide insight into the mechanisms by which KATNB1 mutations cause human cerebral cortical malformations, demonstrating its fundamental role during brain development.

}, keywords = {Adenosine Triphosphatases, Animals, Brain, Cell Count, Cell Division, Dendrites, Drosophila, Drosophila Proteins, Humans, Katanin, Mice, Microcephaly, Microtubule-Associated Proteins, Mutation, Neural Stem Cells, Neurogenesis, Optic Lobe, Nonmammalian, Spindle Apparatus, Zebrafish}, issn = {1097-4199}, doi = {10.1016/j.neuron.2014.12.014}, author = {Mishra-Gorur, Ketu and {\c C}a{\u g}layan, Ahmet Okay and Schaffer, Ashleigh E and Chabu, Chiswili and Henegariu, Octavian and Vonhoff, Fernando and Akg{\"u}m{\"u}{\c s}, G{\"o}zde Tu{\u g}ce and Nishimura, Sayoko and Han, Wenqi and Tu, Shu and Baran, Bur{\c c}in and G{\"u}m{\"u}{\c s}, Hakan and Dilber, Cengiz and Zaki, Maha S and Hossni, Heba A A and Rivi{\`e}re, Jean-Baptiste and Kayserili, H{\"u}lya and Spencer, Emily G and Rosti, Rasim O and Schroth, Jana and Per, H{\"u}seyin and Caglar, Caner and {\c C}a{\u g}lar, {\c C}a{\u g}ri and D{\"o}len, Duygu and Baranoski, Jacob F and Kumanda{\c s}, Sefer and Minja, Frank J and Erson-Omay, E Zeynep and Mane, Shrikant M and Lifton, Richard P and Xu, Tian and Keshishian, Haig and Dobyns, William B and Chi, Neil C and {\v S}estan, Nenad and Louvi, Angeliki and Bilguvar, Kaya and Yasuno, Katsuhito and Gleeson, Joseph G and G{\"u}nel, Murat} } @article {287, title = {Mutations in VRK1 associated with complex motor and sensory axonal neuropathy plus microcephaly.}, journal = {JAMA Neurol}, volume = {70}, year = {2013}, month = {2013 Dec}, pages = {1491-8}, abstract = {

IMPORTANCE: Patients with rare diseases and complex clinical presentations represent a challenge for clinical diagnostics. Genomic approaches are allowing the identification of novel variants in genes for very rare disorders, enabling a molecular diagnosis. Genomics is also revealing a phenotypic expansion whereby the full spectrum of clinical expression conveyed by mutant alleles at a locus can be better appreciated.

OBJECTIVE: To elucidate the molecular cause of a complex neuropathy phenotype in 3 patients by applying genomic sequencing strategies.

DESIGN, SETTING, AND PARTICIPANTS: Three affected individuals from 2 unrelated families presented with a complex neuropathy phenotype characterized by axonal sensorimotor neuropathy and microcephaly. They were recruited into the Centers for Mendelian Genomics research program to identify the molecular cause of their phenotype. Whole-genome, targeted whole-exome sequencing, and high-resolution single-nucleotide polymorphism arrays were performed in genetics clinics of tertiary care pediatric hospitals and biomedical research institutions.

MAIN OUTCOMES AND MEASURES: Whole-genome and whole-exome sequencing identified the variants responsible for the patients{\textquoteright} clinical phenotype.

RESULTS: We identified compound heterozygous alleles in 2 affected siblings from 1 family and a homozygous nonsense variant in the third unrelated patient in the vaccinia-related kinase 1 gene (VRK1). In the latter subject, we found a common haplotype on which the nonsense mutation occurred and that segregates in the Ashkenazi Jewish population.

CONCLUSIONS AND RELEVANCE: We report the identification of disease-causing alleles in 3 children from 2 unrelated families with a previously uncharacterized complex axonal motor and sensory neuropathy accompanied by severe nonprogressive microcephaly and cerebral dysgenesis. Our data raise the question of whether VRK1 mutations disturb cell cycle progression and may result in apoptosis of cells in the nervous system. The application of unbiased genomic approaches allows the identification of potentially pathogenic mutations in unsuspected genes in highly genetically heterogeneous and uncharacterized neurological diseases.

}, keywords = {Child, Child, Preschool, DNA Mutational Analysis, Female, Genotype, Hereditary Sensory and Motor Neuropathy, Humans, Infant, Intracellular Signaling Peptides and Proteins, Magnetic Resonance Imaging, Male, Microcephaly, Mutation, Neural Conduction, Polymorphism, Single Nucleotide, Protein-Serine-Threonine Kinases}, issn = {2168-6157}, doi = {10.1001/jamaneurol.2013.4598}, author = {Gonzaga-Jauregui, Claudia and Lotze, Timothy and Jamal, Leila and Penney, Samantha and Campbell, Ian M and Pehlivan, Davut and Hunter, Jill V and Woodbury, Suzanne L and Raymond, Gerald and Adesina, Adekunle M and Jhangiani, Shalini N and Reid, Jeffrey G and Muzny, Donna M and Boerwinkle, Eric and Lupski, James R and Gibbs, Richard A and Wiszniewski, Wojciech} }