@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 {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 {500, title = {Genetic variants in components of the NALCN-UNC80-UNC79 ion channel complex cause a broad clinical phenotype (NALCN channelopathies).}, journal = {Hum Genet}, volume = {137}, year = {2018}, month = {2018 Sep}, pages = {753-768}, abstract = {

NALCN is a conserved cation channel, which conducts a permanent sodium leak current and regulates resting membrane potential and neuronal excitability. It is part of a large ion channel complex, the "NALCN channelosome", consisting of multiple proteins including UNC80 and UNC79. The predominant neuronal expression pattern and its function suggest an important role in neuronal function and disease. So far, biallelic NALCN and UNC80 variants have been described in a small number of individuals leading to infantile hypotonia, psychomotor retardation, and characteristic facies 1 (IHPRF1, OMIM 615419) and 2 (IHPRF2, OMIM 616801), respectively. Heterozygous de novo NALCN missense variants in the S5/S6 pore-forming segments lead to congenital contractures of the limbs and face, hypotonia, and developmental delay (CLIFAHDD, OMIM 616266) with some clinical overlap. In this study, we present detailed clinical information of 16 novel individuals with biallelic NALCN variants, 1 individual with a heterozygous de novo NALCN missense variant and an interesting clinical phenotype without contractures, and 12 individuals with biallelic UNC80 variants. We report for the first time a missense NALCN variant~located in the predicted S6 pore-forming unit inherited in an autosomal-recessive manner leading to mild IHPRF1. We show evidence of clinical variability, especially among IHPRF1-affected individuals, and discuss differences between the IHPRF1- and IHPRF2 phenotypes. In summary, we provide a comprehensive overview of IHPRF1 and IHPRF2 phenotypes based on the largest cohort of individuals reported so far and provide additional insights into the clinical phenotypes of these neurodevelopmental diseases to help improve counseling of affected families.

}, keywords = {Adolescent, Adult, Carrier Proteins, Channelopathies, Child, Child, Preschool, Developmental Disabilities, Female, Genetic Markers, Genetic Variation, Humans, Infant, Infant, Newborn, Male, Membrane Proteins, Phenotype, Sodium Channels, Young Adult}, issn = {1432-1203}, doi = {10.1007/s00439-018-1929-5}, author = {Bramswig, Nuria C and Bertoli-Avella, Aida M and Albrecht, Beate and Al Aqeel, Aida I and Alhashem, Amal and Al-Sannaa, Nouriya and Bah, Maissa and Br{\"o}hl, Katharina and Depienne, Christel and Dorison, Nathalie and Doummar, Diane and Ehmke, Nadja and Elbendary, Hasnaa M and Gorokhova, Svetlana and H{\'e}ron, Delphine and Horn, Denise and James, Kiely and Keren, Boris and Kuechler, Alma and Ismail, Samira and Issa, Mahmoud Y and Marey, Isabelle and Mayer, Mich{\`e}le and McEvoy-Venneri, Jennifer and Megarbane, Andre and Mignot, Cyril and Mohamed, Sarar and Nava, Caroline and Philip, Nicole and Ravix, Cecile and Rolfs, Arndt and Sadek, Abdelrahim Abdrabou and Segebrecht, Lara and Stanley, Valentina and Trautman, Camille and Valence, Stephanie and Villard, Laurent and Wieland, Thomas and Engels, Hartmut and Strom, Tim M and Zaki, Maha S and Gleeson, Joseph G and L{\"u}decke, Hermann-Josef and Bauer, Peter and Wieczorek, Dagmar} } @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 {493, title = {Mutations in GPAA1, Encoding a GPI Transamidase Complex Protein, Cause Developmental Delay, Epilepsy, Cerebellar Atrophy, and Osteopenia.}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Nov 02}, pages = {856-865}, abstract = {

Approximately one in every 200 mammalian proteins is anchored to the cell membrane through a glycosylphosphatidylinositol (GPI) anchor. These proteins play important roles notably in neurological development and function. To date, more than 20 genes have been implicated in the biogenesis of GPI-anchored proteins. GPAA1 (glycosylphosphatidylinositol anchor attachment 1) is an essential component of the transamidase complex along with PIGK, PIGS, PIGT, and PIGU (phosphatidylinositol-glycan biosynthesis classes K, S, T, and U, respectively). This complex orchestrates the attachment of the GPI anchor to the C terminus of precursor proteins in the endoplasmic reticulum. Here, we report bi-allelic mutations in GPAA1 in ten individuals from five families. Using whole-exome sequencing, we identified two frameshift mutations (c.981_993del [p.Gln327Hisfs102] and c.920delG [p.Gly307Alafs11]), one intronic splicing mutation (c.1164+5C>T), and six missense mutations (c.152C>T [p.Ser51Leu], c.160_161delinsAA [p.Ala54Asn], c.527G>C [p.Trp176Ser], c.869T>C [p.Leu290Pro], c.872T>C [p.Leu291Pro], and c.1165G>C [p.Ala389Pro]). Most individuals presented with global developmental delay, hypotonia, early-onset seizures, cerebellar atrophy, and osteopenia. The splicing mutation was found to decrease GPAA1 mRNA. Moreover, flow-cytometry analysis of five available individual samples showed that several GPI-anchored proteins had decreased cell-surface abundance in leukocytes (FLAER, CD16, and CD59) or fibroblasts (CD73 and CD109). Transduction of fibroblasts with a lentivirus encoding the wild-type protein partially rescued the deficiency of GPI-anchored proteins. These findings highlight the role of the transamidase complex in the development and function of the cerebellum and the skeletal system.

}, keywords = {Acyltransferases, Adolescent, Adult, Alleles, Atrophy, Bone Diseases, Metabolic, Cerebellum, Child, Child, Preschool, Developmental Disabilities, Epilepsy, Exome, Female, Fibroblasts, Glycosylphosphatidylinositols, Humans, Male, Membrane Glycoproteins, Muscle Hypotonia, Mutation, Pedigree, RNA, Messenger, Seizures}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.09.020}, author = {Nguyen, Thi Tuyet Mai and Murakami, Yoshiko and Sheridan, Eamonn and Ehresmann, Sophie and Rousseau, Justine and St-Denis, Anik and Chai, Guoliang and Ajeawung, Norbert F and Fairbrother, Laura and Reimschisel, Tyler and Bateman, Alexandra and Berry-Kravis, Elizabeth and Xia, Fan and Tardif, Jessica and Parry, David A and Logan, Clare V and Diggle, Christine and Bennett, Christopher P and Hattingh, Louise and Rosenfeld, Jill A and Perry, Michael Scott and Parker, Michael J and Le Deist, Fran{\c c}oise and Zaki, Maha S and Ignatius, Erika and Isohanni, Pirjo and L{\"o}nnqvist, Tuula and Carroll, Christopher J and Johnson, Colin A and Gleeson, Joseph G and Kinoshita, Taroh and Campeau, Philippe M} } @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 {179, title = {Biallelic mutations in SNX14 cause a syndromic form of cerebellar atrophy and lysosome-autophagosome dysfunction.}, journal = {Nat Genet}, volume = {47}, year = {2015}, month = {2015 May}, pages = {528-34}, abstract = {

Pediatric-onset ataxias often present clinically as developmental delay and intellectual disability, with prominent cerebellar atrophy as a key neuroradiographic finding. Here we describe a new clinically distinguishable recessive syndrome in 12 families with cerebellar atrophy together with ataxia, coarsened facial features and intellectual disability, due to truncating mutations in the sorting nexin gene SNX14, encoding a ubiquitously expressed modular PX domain-containing sorting factor. We found SNX14 localized to lysosomes and associated with phosphatidylinositol (3,5)-bisphosphate, a key component of late endosomes/lysosomes. Patient-derived cells showed engorged lysosomes and a slower autophagosome clearance rate upon autophagy induction by starvation. Zebrafish morphants for snx14 showed dramatic loss of cerebellar parenchyma, accumulation of autophagosomes and activation of apoptosis. Our results characterize a unique ataxia syndrome due to biallelic SNX14 mutations leading to lysosome-autophagosome dysfunction.

}, keywords = {Animals, Atrophy, Autophagy, Cerebellar Diseases, Cerebellum, Child, Preschool, Female, Gene Frequency, Humans, Infant, Lod Score, Lysosomal Storage Diseases, Lysosomes, Male, Mutation, Phagosomes, Sorting Nexins, Spinocerebellar Ataxias, Syndrome, Zebrafish}, issn = {1546-1718}, doi = {10.1038/ng.3256}, author = {Akizu, Naiara and Cantagrel, Vincent and Zaki, Maha S and Al-Gazali, Lihadh and Wang, Xin and Rosti, Rasim Ozgur and Dikoglu, Esra and Gelot, Antoinette Bernabe and Rosti, Basak and Vaux, Keith K and Scott, Eric M and Silhavy, Jennifer L and Schroth, Jana and Copeland, Brett and Schaffer, Ashleigh E and Gordts, Philip L S M and Esko, Jeffrey D and Buschman, Matthew D and Field, Seth J and Napolitano, Gennaro and Abdel-Salam, Ghada M and Ozgul, R Koksal and Sag{\i}roglu, Mahmut Samil and Azam, Matloob and Ismail, Samira and Aglan, Mona and Selim, Laila and Mahmoud, Iman G and Abdel-Hadi, Sawsan and Badawy, Amera El and Sadek, Abdelrahim A and Mojahedi, Faezeh and Kayserili, H{\"u}lya and Masri, Amira and Bastaki, Laila and Temtamy, Samia and M{\"u}ller, Ulrich and Desguerre, Isabelle and Casanova, Jean-Laurent and Dursun, Ali and G{\"u}nel, Murat and Gabriel, Stacey B and de Lonlay, Pascale 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} }