@article {1018, title = {Resolution of sclerotic lesions of dysosteosclerosis due to biallelic SLC29A3 variant in a Turkish girl.}, journal = {Am J Med Genet A}, year = {2021}, month = {2021 Apr 10}, abstract = {

Dysosteosclerosis is a group of sclerosing bone dysplasia characterized by short stature, increased bone fragility, osteosclerosis, and platyspondyly. It is a genetically heterogeneous disorder caused by biallelic mutations in the SLC29A3, TNFRSF11A, TCIRG1, and CSF1R genes. To date, four dysosteosclerosis patients with SLC29A3 mutations have been reported. Here, we report biallelic SLC29A3 (c.303_320dupCTACTTTGAGAGCTACCT) variant in a three-year-old girl. She had large anterior fontanelle, fracture history, short stature, camptodactyly, elbow contracture, and melanocytic nevus. Initial skeletal radiographs revealed platyspondyly, dense vertebral endplates (sandwich appearance of the vertebral bodies), diffuse sclerosis of the peripheral side of the pelvic bones, sclerosis of metaphysis and diaphysis of the long bones, metaphyseal widening, and diaphyseal cortical thickening. Mild sclerosis was also present in the skull base, maxilla, rib, scapula, and phalanges. Notably, we observed that sandwich vertebrae appearance significantly resolved and sclerosis of ribs, scapula, pelvis, and long bone metaphysis regressed over a 2.5-year period. However, platyspondyly, metaphyseal widening, and diaphyseal cortical thickening persisted. In conclusion, this study demonstrates spontaneous resolution of osteosclerosis, which was not described previously in patients with dysosteosclerosis.

}, issn = {1552-4833}, doi = {10.1002/ajmg.a.62198}, author = {Uluda{\u g} Alkaya, Dilek and Akp{\i}nar, Evren and Bilguvar, Kaya and Tuysuz, Beyhan} } @article {790, title = {Bi-allelic GAD1 variants cause a neonatal onset syndromic developmental and epileptic encephalopathy.}, journal = {Brain}, volume = {143}, year = {2020}, month = {2020 05 01}, pages = {1447-1461}, abstract = {

Developmental and epileptic encephalopathies are a heterogeneous group of early-onset epilepsy syndromes dramatically impairing neurodevelopment. Modern genomic technologies have revealed a number of monogenic origins and opened the door to therapeutic hopes. Here we describe a new syndromic developmental and epileptic encephalopathy caused by bi-allelic loss-of-function variants in GAD1, as presented by 11 patients from six independent consanguineous families. Seizure onset occurred in the first 2 months of life in all patients. All 10 patients, from whom early disease history was available, presented with seizure onset in the first month of life, mainly consisting of epileptic spasms or myoclonic seizures. Early EEG showed suppression-burst or pattern of burst attenuation or hypsarrhythmia if only recorded in the post-neonatal period. Eight patients had joint contractures and/or pes equinovarus. Seven patients presented a cleft palate and two also had an omphalocele, reproducing the phenotype of the knockout Gad1-/- mouse model. Four patients died before 4 years of age. GAD1 encodes the glutamate decarboxylase enzyme GAD67, a critical actor of the γ-aminobutyric acid (GABA) metabolism as it catalyses the decarboxylation of glutamic acid to form GABA. Our findings evoke a novel syndrome related to GAD67 deficiency, characterized by the unique association of developmental and epileptic encephalopathies, cleft palate, joint contractures and/or omphalocele.

}, keywords = {Abnormalities, Multiple, Epileptic Syndromes, Female, Glutamate Decarboxylase, Humans, Infant, Newborn, Male, Mutation, Pedigree}, issn = {1460-2156}, doi = {10.1093/brain/awaa085}, author = {Chatron, Nicolas and Becker, Felicitas and Morsy, Heba and Schmidts, Miriam and Hardies, Katia and Tuysuz, Beyhan and Roselli, Sandra and Najafi, Maryam and Alkaya, Dilek Uludag and Ashrafzadeh, Farah and Nabil, Amira and Omar, Tarek and Maroofian, Reza and Karimiani, Ehsan Ghayoor and Hussien, Haytham and Kok, Fernando and Ramos, Luiza and Gunes, Nilay and Bilguvar, Kaya and Labalme, Audrey and Alix, Eudeline and Sanlaville, Damien and de Bellescize, Julitta and Poulat, Anne-Lise and Moslemi, Ali-Reza and Lerche, Holger and May, Patrick and Lesca, Gaetan and Weckhuysen, Sarah and Tajsharghi, Homa} } @article {672, title = {The Genomics of Arthrogryposis, a Complex Trait: Candidate Genes and Further Evidence for Oligogenic Inheritance.}, journal = {Am J Hum Genet}, volume = {105}, year = {2019}, month = {2019 Jul 03}, pages = {132-150}, abstract = {

Arthrogryposis is a clinical finding that is present either as a feature of a neuromuscular condition or as part of a systemic disease in over 400 Mendelian conditions. The underlying molecular etiology remains largely unknown because of genetic and phenotypic heterogeneity. We applied exome sequencing (ES) in a cohort of 89 families with the clinical sign of arthrogryposis. Additional molecular techniques including array comparative genomic hybridization (aCGH) and Droplet Digital PCR (ddPCR) were performed on individuals who were found to have pathogenic copy number variants (CNVs) and mosaicism, respectively. A molecular diagnosis was established in 65.2\% (58/89) of families. Eleven out of 58 families (19.0\%) showed evidence for potential involvement of pathogenic variation at more than one locus, probably driven by absence of heterozygosity (AOH) burden due to identity-by-descent (IBD). RYR3, MYOM2, ERGIC1, SPTBN4, and ABCA7 represent genes, identified in two or more families, for which mutations are probably causative for arthrogryposis. We also provide evidence for the involvement of CNVs in the etiology of arthrogryposis and for the idea that both mono-allelic and bi-allelic variants in the same gene cause either similar or distinct syndromes. We were able to identify the molecular etiology in nine out of 20 families who underwent reanalysis. In summary, our data from family-based ES further delineate the molecular etiology of arthrogryposis, yielded several candidate disease-associated genes, and provide evidence for mutational burden in a biological pathway or network. Our study also highlights the importance of reanalysis of individuals with unsolved diagnoses in conjunction with sequencing extended family members.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2019.05.015}, author = {Pehlivan, Davut and Bayram, Yavuz and Gunes, Nilay and Coban Akdemir, Zeynep and Shukla, Anju and Bierhals, Tatjana and Tabakci, Burcu and Sahin, Yavuz and Gezdirici, Alper and Fatih, Jawid M and Gulec, Elif Yilmaz and Yesil, G{\"o}zde and Punetha, Jaya and Ocak, Zeynep and Grochowski, Christopher M and Karaca, Ender and Albayrak, Hatice Mutlu and Radhakrishnan, Periyasamy and Erdem, Haktan Bagis and Sahin, Ibrahim and Yildirim, Timur and Bayhan, Ilhan A and Bursali, Aysegul and Elmas, Muhsin and Yuksel, Zafer and Ozdemir, Ozturk and Silan, Fatma and Yildiz, Onur and Yesilbas, Osman and Isikay, Sedat and Balta, Burhan and Gu, Shen and Jhangiani, Shalini N and Doddapaneni, Harsha and Hu, Jianhong and Muzny, Donna M and Boerwinkle, Eric and Gibbs, Richard A and Tsiakas, Konstantinos and Hempel, Maja and Girisha, Katta Mohan and Gul, Davut and Posey, Jennifer E and Elcioglu, Nursel H and Tuysuz, Beyhan and Lupski, James R} } @article {740, title = {Mutations in ANKLE2, a ZIKA Virus Target, Disrupt an Asymmetric Cell Division Pathway in Drosophila Neuroblasts to Cause Microcephaly.}, journal = {Dev Cell}, volume = {51}, year = {2019}, month = {2019 Dec 16}, pages = {713-729.e6}, abstract = {

The apical Par complex, which contains atypical protein kinase C (aPKC), Bazooka (Par-3), and Par-6, is required for establishing polarity during asymmetric division of neuroblasts in Drosophila, and its activity depends on L(2)gl. We show that loss of Ankle2, a protein associated with microcephaly in humans and known to interact with Zika protein NS4A, reduces brain volume in flies and impacts the function of the Par complex. Reducing Ankle2 levels disrupts endoplasmic reticulum (ER) and nuclear envelope morphology, releasing the kinase Ballchen-VRK1 into the cytosol. These defects are associated with reduced phosphorylation of aPKC, disruption of Par-complex localization, and spindle alignment defects. Importantly, removal of one copy of ballchen or l(2)gl suppresses Ankle2 mutant phenotypes and restores viability and brain size. Human mutational studies implicate the above-mentioned genes in microcephaly and motor neuron disease. We suggest that NS4A, ANKLE2, VRK1, and LLGL1 define a pathway impinging on asymmetric determinants of neural stem cell division.

}, issn = {1878-1551}, doi = {10.1016/j.devcel.2019.10.009}, author = {Link, Nichole and Chung, Hyunglok and Jolly, Angad and Withers, Marjorie and Tepe, Burak and Arenkiel, Benjamin R and Shah, Priya S and Krogan, Nevan J and Aydin, Hatip and Geckinli, Bilgen B and Tos, Tulay and Isikay, Sedat and Tuysuz, Beyhan and Mochida, Ganesh H and Thomas, Ajay X and Clark, Robin D and Mirzaa, Ghayda M and Lupski, James R and Bellen, Hugo J} } @article {542, title = {Genotype-phenotype investigation of 35 patients from 11 unrelated families with camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome.}, journal = {Mol Genet Genomic Med}, volume = {6}, year = {2018}, month = {2018 03}, pages = {230-248}, abstract = {

BACKGROUND: The camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP) is a rare autosomal recessive condition characterized by camptodactyly, noninflammatory arthropathy, coxa vara, and pericarditis. CACP is caused by mutations in the proteoglycan 4 (PRG4) gene, which encodes a lubricating glycoprotein present in the synovial fluid and at the surface of articular cartilage.

METHODS: In the present study, we compared the clinical and molecular findings of CACP syndrome in 35 patients from 11 unrelated families. In 28 patients, whole exome sequencing was used to investigate genomic variations.

RESULTS: We found that camptodactyly of hands was the first symptom presented by most patients. Swelling of wrists, knees, and elbows began before 4~years of age, while the age of joint involvement was variable. Patients reported an increased pain level after the age of 10, and severe hip involvement developed after 20~years old. All patients presented developmental coxa vara and seven patients (~22\%) had pleural effusion, pericarditis, and/or ascites. We identified nine novel genomic alterations, including the first case of homozygous complete deletion of exon 1 in the PRG4 gene.

CONCLUSION: With this study, we contribute to the catalog of CACP causing variants. We confirm that the skeletal component of this disease worsens with age, and presents the potential mechanisms for interfamily variability, by discussing the influence of a modifier gene and escape from nonsense-mediated mRNA decay. We believe that this report will increase awareness of this familial arthropathic condition and the characteristic clinical and radiological findings will facilitate the differentiation from the common childhood rheumatic diseases such as juvenile idiopathic arthritis.

}, keywords = {Adolescent, Adult, Arthropathy, Neurogenic, Child, Child, Preschool, Coxa Vara, Exons, Female, Genetic Association Studies, Hand Deformities, Congenital, Humans, Male, Middle Aged, Mutation, Proteoglycans, Retrospective Studies, Sequence Deletion, Synovitis, Whole Exome Sequencing}, issn = {2324-9269}, doi = {10.1002/mgg3.364}, author = {Yilmaz, Saliha and Uluda{\u g} Alkaya, Dilek and Kasapcopur, Ozgur and Barut, Kenan and Akdemir, Ekin S and Celen, Cemre and Youngblood, Mark W and Yasuno, Katsuhito and Bilguvar, Kaya and G{\"u}nel, Murat and Tuysuz, Beyhan} } @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 {95, title = {Molecular etiology of arthrogryposis in multiple families of mostly Turkish origin.}, journal = {J Clin Invest}, volume = {126}, year = {2016}, month = {2016 Feb}, pages = {762-78}, abstract = {

BACKGROUND: Arthrogryposis, defined as congenital joint contractures in 2 or more body areas, is a clinical sign rather than a specific disease diagnosis. To date, more than 400 different disorders have been described that present with arthrogryposis, and variants of more than 220 genes have been associated with these disorders; however, the underlying molecular etiology remains unknown in the considerable majority of these cases.

METHODS: We performed whole exome sequencing (WES) of 52 patients with clinical presentation of arthrogryposis from 48 different families.

RESULTS: Affected individuals from 17 families (35.4\%) had variants in known arthrogryposis-associated genes, including homozygous variants of cholinergic γ nicotinic receptor (CHRNG, 6 subjects) and endothelin converting enzyme-like 1 (ECEL1, 4 subjects). Deleterious variants in candidate arthrogryposis-causing genes (fibrillin 3 [FBN3], myosin IXA [MYO9A], and pleckstrin and Sec7 domain containing 3 [PSD3]) were identified in 3 families (6.2\%). Moreover, in 8 families with a homozygous mutation in an arthrogryposis-associated gene, we identified a second locus with either a homozygous or compound heterozygous variant in a candidate gene (myosin binding protein C, fast type [MYBPC2] and vacuolar protein sorting 8 [VPS8], 2 families, 4.2\%) or in another disease-associated genes (6 families, 12.5\%), indicating a potential mutational burden contributing to disease expression.

CONCLUSION: In 58.3\% of families, the arthrogryposis manifestation could be explained by a molecular diagnosis; however, the molecular etiology in subjects from 20 families remained unsolved by WES. Only 5 of these 20 unrelated subjects had a clinical presentation consistent with amyoplasia; a phenotype not thought to be of genetic origin. Our results indicate that increased use of genome-wide technologies will provide opportunities to better understand genetic models for diseases and molecular mechanisms of genetically heterogeneous disorders, such as arthrogryposis.

FUNDING: This work was supported in part by US National Human Genome Research Institute (NHGRI)/National Heart, Lung, and Blood Institute (NHLBI) grant U54HG006542 to the Baylor-Hopkins Center for Mendelian Genomics, and US National Institute of Neurological Disorders and Stroke (NINDS) grant R01NS058529 to J.R. Lupski.

}, keywords = {Arthrogryposis, Exome, Family, Female, Genome-Wide Association Study, Humans, Male, Turkey}, issn = {1558-8238}, doi = {10.1172/JCI84457}, author = {Bayram, Yavuz and Karaca, Ender and Coban Akdemir, Zeynep and Yilmaz, Elif Ozdamar and Tayfun, Gulsen Akay and Aydin, Hatip and Torun, Deniz and Bozdogan, Sevcan Tug and Gezdirici, Alper and Isikay, Sedat and Atik, Mehmed M and Gambin, Tomasz and Harel, Tamar and El-Hattab, Ayman W and Charng, Wu-Lin and Pehlivan, Davut and Jhangiani, Shalini N and Muzny, Donna M and Karaman, Ali and Celik, Tamer and Yuregir, Ozge Ozalp and Yildirim, Timur and Bayhan, Ilhan A and Boerwinkle, Eric and Gibbs, Richard A and Elcioglu, Nursel and Tuysuz, Beyhan and Lupski, James R} } @article {96, title = {A patient with a novel homozygous missense mutation in FTO and concomitant nonsense mutation in CETP.}, journal = {J Hum Genet}, volume = {61}, year = {2016}, month = {2016 May}, pages = {395-403}, abstract = {

The fat mass and obesity associated (FTO) gene has previously been associated with a variety of diseases and conditions, notably obesity, acute coronary syndrome and metabolic syndrome. Reports describing mutations in FTO as well as in FTO animal models have further demonstrated a role for FTO in the development of the brain and other organs. Here, we describe a patient born of consanguineous union who presented with microcephaly, developmental delay, behavioral abnormalities, dysmorphic facial features, hypotonia and other various phenotypic abnormalities. Whole-exome sequencing revealed a novel homozygous missense mutation in FTO and a nonsense mutation in the cholesteryl ester transfer protein (CETP). Exome copy number variation analysis revealed no disease-causing large duplications or deletions within coding regions. Patient{\textquoteright}s, her parents{\textquoteright} and non-related control{\textquoteright} fibroblasts were analyzed for morphologic defects, abnormal proliferation, apoptosis and transcriptome profile. We have shown that FTO is located in the nucleus of cells from each tested sample. Western blot analysis demonstrated no changes in patient FTO. Quantitative (qPCR) analysis revealed slightly decreased levels of FTO expression in patient cells compared with controls. No morphological or proliferation differences between the patient and control fibroblasts were observed. There is still much to be learned about the molecular mechanisms by which mutations in FTO contribute to such severe phenotypes.

}, keywords = {Alpha-Ketoglutarate-Dependent Dioxygenase FTO, Apoptosis, Biopsy, Child, Preschool, Cholesterol Ester Transfer Proteins, Computational Biology, Consanguinity, DNA Copy Number Variations, DNA Mutational Analysis, Exome, Female, Gene Expression, Gene Expression Profiling, Genetic Association Studies, Genotype, High-Throughput Nucleotide Sequencing, Homozygote, Humans, Mutation, Missense, Phenotype, Transcriptome}, issn = {1435-232X}, doi = {10.1038/jhg.2015.160}, author = {{\c C}a{\u g}layan, Ahmet O and Tuysuz, Beyhan and Co{\c s}kun, S{\"u}leyman and Quon, Jennifer and Harmanc{\i}, Akdes S and Baranoski, Jacob F and Baran, Bur{\c c}in and Erson-Omay, E Zeynep and Henegariu, Octavian and Mane, Shrikant M and Bilguvar, Kaya and Yasuno, Katsuhito and G{\"u}nel, Murat} } @article {140, title = {Phenotypic Expansion of Congenital Disorder of Glycosylation Due to SRD5A3 Null Mutation.}, journal = {JIMD Rep}, volume = {26}, year = {2016}, month = {2016}, pages = {7-12}, abstract = {

We present a boy, admitted at 4 months, with facial dysmorphism, hypertrichosis, loose skin, bilateral inguinal hernia, severe hypotonia, psychomotor disability, seizures with hypsarrhythmia (West syndrome), hepatosplenomegaly, increased serum transaminases, iris coloboma, glaucoma, corneal clouding and bilateral dilated lateral ventricles, and extra-axial post-cerebellar space. Serum transferrin isoelectrofocusing (IEF) showed a type 1 pattern. Whole-exome genotyping showed a previously reported homozygous nonsense mutation c.320G>A; p.Trp107X in SRD5A3. Epilepsy and glaucoma have been reported only once in the 19 described SRD5A3-congenital glycosylation defect patients, and corneal clouding not at all.

}, issn = {2192-8304}, doi = {10.1007/8904_2015_478}, author = {Tuysuz, Beyhan and Pehlivan, Davut and {\"O}zk{\"o}k, Ahmet and Jhangiani, Shalini and Yalcinkaya, Cengiz and Zeybek, {\c C}i{\u g}dem Aktu{\u g}lu and Muzny, Donna Marie and Lupski, James R and Gibbs, Richard and Jaeken, Jaak} } @article {198, title = {Global transcriptional disturbances underlie Cornelia de Lange syndrome and related phenotypes.}, journal = {J Clin Invest}, volume = {125}, year = {2015}, month = {2015 Feb}, pages = {636-51}, abstract = {

Cornelia de Lange syndrome (CdLS) is a genetically heterogeneous disorder that presents with extensive phenotypic variability, including facial dysmorphism, developmental delay/intellectual disability (DD/ID), abnormal extremities, and hirsutism. About 65\% of patients harbor mutations in genes that encode subunits or regulators of the cohesin complex, including NIPBL, SMC1A, SMC3, RAD21, and HDAC8. Wiedemann-Steiner syndrome (WDSTS), which shares CdLS phenotypic features, is caused by mutations in lysine-specific methyltransferase 2A (KMT2A). Here, we performed whole-exome sequencing (WES) of 2 male siblings clinically diagnosed with WDSTS; this revealed a hemizygous, missense mutation in SMC1A that was predicted to be deleterious. Extensive clinical evaluation and WES of 32 Turkish patients clinically diagnosed with CdLS revealed the presence of a de novo heterozygous nonsense KMT2A mutation in 1 patient without characteristic WDSTS features. We also identified de novo heterozygous mutations in SMC3 or SMC1A that affected RNA splicing in 2 independent patients with combined CdLS and WDSTS features. Furthermore, in families from 2 separate world populations segregating an autosomal-recessive disorder with CdLS-like features, we identified homozygous mutations in TAF6, which encodes a core transcriptional regulatory pathway component. Together, our data, along with recent transcriptome studies, suggest that CdLS and related phenotypes may be "transcriptomopathies" rather than cohesinopathies.

}, keywords = {Adolescent, Adult, Cell Cycle Proteins, Child, Child, Preschool, Chondroitin Sulfate Proteoglycans, Chromosomal Proteins, Non-Histone, Codon, Nonsense, De Lange Syndrome, Exome, Exonucleases, Gene Expression Profiling, Gene Expression Regulation, Genome-Wide Association Study, Heterozygote, Histone Deacetylases, Histone-Lysine N-Methyltransferase, Humans, Infant, Male, Myeloid-Lymphoid Leukemia Protein, Phenotype, Proteins, Repressor Proteins, Transcriptome}, issn = {1558-8238}, doi = {10.1172/JCI77435}, author = {Yuan, Bo and Pehlivan, Davut and Karaca, Ender and Patel, Nisha and Charng, Wu-Lin and Gambin, Tomasz and Gonzaga-Jauregui, Claudia and Sutton, V Reid and Yesil, G{\"o}zde and Bozdogan, Sevcan Tug and Tos, Tulay and Koparir, Asuman and Koparir, Erkan and Beck, Christine R and Gu, Shen and Aslan, Huseyin and Yuregir, Ozge Ozalp and Al Rubeaan, Khalid and Alnaqeb, Dhekra and Alshammari, Muneera J and Bayram, Yavuz and Atik, Mehmed M and Aydin, Hatip and Geckinli, B Bilge and Seven, Mehmet and Ulucan, Hakan and Fenercioglu, Elif and Ozen, Mustafa and Jhangiani, Shalini and Muzny, Donna M and Boerwinkle, Eric and Tuysuz, Beyhan and Alkuraya, Fowzan S and Gibbs, Richard A and Lupski, James R} } @article {208, title = {Brain malformations associated with Knobloch syndrome--review of literature, expanding clinical spectrum, and identification of novel mutations.}, journal = {Pediatr Neurol}, volume = {51}, year = {2014}, month = {2014 Dec}, pages = {806-813.e8}, abstract = {

BACKGROUND: Knobloch syndrome is a rare, autosomal recessive, developmental disorder characterized by stereotyped ocular abnormalities with or without occipital skull deformities (encephalocele, bone defects, and cutis aplasia). Although there is clear heterogeneity in clinical presentation, central nervous system malformations, aside from the characteristic encephalocele, have not typically been considered a component of the disease phenotype.

METHODS: Four patients originally presented for genetic evaluation of symptomatic structural brain malformations. Whole-genome genotyping, whole-exome sequencing, and confirmatory Sanger sequencing were performed. Using immunohistochemical analysis, we investigated the protein expression pattern of COL18A1 in the mid-fetal and adult human cerebral cortex and then analyzed the spatial and temporal changes in the expression pattern of COL18A1 during human cortical development using the Human Brain Transcriptome database.

RESULTS: We identified two novel homozygous deleterious frame-shift mutations in the COL18A1 gene. On further investigation of these patients and their families, we found that many exhibited certain characteristics of Knobloch syndrome, including pronounced ocular defects. Our data strongly support an important role for COL18A1 in brain development, and this report contributes to an enhanced characterization of the brain malformations that can result from deficiencies of collagen XVIII.

CONCLUSIONS: This case series highlights the diagnostic power and clinical utility of whole-exome sequencing technology-allowing clinicians and physician scientists to better understand the pathophysiology and presentations of rare diseases. We suggest that patients who are clinically diagnosed with Knobloch syndrome and/or found to have COL18A1 mutations via genetic screening should be investigated for potential structural brain abnormalities even in the absence of an encephalocele.

}, keywords = {Adolescent, Adult, Cerebral Cortex, Collagen Type XVIII, Consanguinity, Encephalocele, Exome, Female, Fetus, Humans, Male, Mutation, Retinal Degeneration, Retinal Detachment, Young Adult}, issn = {1873-5150}, doi = {10.1016/j.pediatrneurol.2014.08.025}, author = {{\c C}a{\u g}layan, Ahmet Okay and Baranoski, Jacob F and Aktar, Fesih and Han, Wengi and Tuysuz, Beyhan and Guzel, Aslan and Guclu, Bulent and Kaymak{\c c}alan, Hande and Aktekin, Berrin and Akg{\"u}m{\"u}{\c s}, G{\"o}zde Tu{\u g}ce and Murray, Phillip B and Erson-Omay, Emine Z and Caglar, Caner and Bakircioglu, Mehmet and Sakalar, Yildirim Bayezit and Guzel, Ebru and Demir, Nihat and Tuncer, Oguz and Senturk, Senem and Ekici, Bar{\i}{\c s} and Minja, Frank J and {\v S}estan, Nenad and Yasuno, Katsuhito and Bilguvar, Kaya and Caksen, Huseyin and G{\"u}nel, Murat} } @article {252, title = {CLP1 founder mutation links tRNA splicing and maturation to cerebellar development and neurodegeneration.}, journal = {Cell}, volume = {157}, year = {2014}, month = {2014 Apr 24}, pages = {651-63}, abstract = {

Neurodegenerative diseases can occur so early as to affect neurodevelopment. From a cohort of more than 2,000 consanguineous families with childhood neurological disease, we identified a founder mutation in four independent pedigrees in cleavage and polyadenylation factor I subunit 1 (CLP1). CLP1 is a multifunctional kinase implicated in tRNA, mRNA, and siRNA maturation. Kinase activity of the CLP1 mutant protein was defective, and the tRNA endonuclease complex (TSEN) was destabilized, resulting in impaired pre-tRNA cleavage. Germline clp1 null zebrafish showed cerebellar neurodegeneration that was rescued by wild-type, but not mutant, human CLP1 expression. Patient-derived induced neurons displayed both depletion of mature tRNAs and accumulation of unspliced pre-tRNAs. Transfection of partially processed tRNA fragments into patient cells exacerbated an oxidative stress-induced reduction in cell survival. Our data link tRNA maturation to neuronal development and neurodegeneration through defective CLP1 function in humans.

}, keywords = {Animals, Brain, Cerebellum, Cleavage And Polyadenylation Specificity Factor, Female, Humans, Male, Mice, Models, Molecular, Neurodegenerative Diseases, Nuclear Proteins, Pedigree, Phosphotransferases, RNA Splicing, RNA, Transfer, Saccharomyces cerevisiae, Transcription Factors, Zebrafish, Zebrafish Proteins}, issn = {1097-4172}, doi = {10.1016/j.cell.2014.03.049}, author = {Schaffer, Ashleigh E and Eggens, Veerle R C and {\c C}a{\u g}layan, Ahmet Okay and Reuter, Miriam S and Scott, Eric and Coufal, Nicole G and Silhavy, Jennifer L and Xue, Yuanchao and Kayserili, H{\"u}lya and Yasuno, Katsuhito and Rosti, Rasim Ozgur and Abdellateef, Mostafa and Caglar, Caner and Kasher, Paul R and Cazemier, J Leonie and Weterman, Marian A and Cantagrel, Vincent and Cai, Na and Zweier, Christiane and Altunoglu, Umut and Satkin, N Bilge and Aktar, Fesih and Tuysuz, Beyhan and Yalcinkaya, Cengiz and Caksen, Huseyin and Bilguvar, Kaya and Fu, Xiang-Dong and Trotta, Christopher R and Gabriel, Stacey and Reis, Andr{\'e} and G{\"u}nel, Murat and Baas, Frank and Gleeson, Joseph G} } @article {311, title = {Recessive loss of function of the neuronal ubiquitin hydrolase UCHL1 leads to early-onset progressive neurodegeneration.}, journal = {Proc Natl Acad Sci U S A}, volume = {110}, year = {2013}, month = {2013 Feb 26}, pages = {3489-94}, abstract = {

Ubiquitin C-terminal hydrolase-L1 (UCHL1), a neuron-specific de-ubiquitinating enzyme, is one of the most abundant proteins in the brain. We describe three siblings from a consanguineous union with a previously unreported early-onset progressive neurodegenerative syndrome featuring childhood onset blindness, cerebellar ataxia, nystagmus, dorsal column dysfuction, and spasticity with upper motor neuron dysfunction. Through homozygosity mapping of the affected individuals followed by whole-exome sequencing of the index case, we identified a previously undescribed homozygous missense mutation within the ubiquitin binding domain of UCHL1 (UCHL1(GLU7ALA)), shared by all affected subjects. As demonstrated by isothermal titration calorimetry, purified UCHL1(GLU7ALA), compared with WT, exhibited at least sevenfold reduced affinity for ubiquitin. In vitro, the mutation led to a near complete loss of UCHL1 hydrolase activity. The GLU7ALA variant is predicted to interfere with the substrate binding by restricting the proper positioning of the substrate for tunneling underneath the cross-over loop spanning the catalytic cleft of UCHL1. This interference with substrate binding, combined with near complete loss of hydrolase activity, resulted in a >100-fold reduction in the efficiency of UCHL1(GLU7ALA) relative to WT. These findings demonstrate a broad requirement of UCHL1 in the maintenance of the nervous system.

}, keywords = {Adult, Age of Onset, Amino Acid Sequence, Base Sequence, Child, Preschool, Exome, Female, Genes, Recessive, Homozygote, Humans, Hydrolysis, Male, Models, Molecular, Molecular Sequence Data, Mutation, Missense, Nerve Degeneration, Neurons, Pedigree, Protein Binding, Sequence Analysis, DNA, Substrate Specificity, Syndrome, Thermodynamics, Ubiquitin, Ubiquitin Thiolesterase}, issn = {1091-6490}, doi = {10.1073/pnas.1222732110}, author = {Bilguvar, Kaya and Tyagi, Navneet K and Ozkara, Cigdem and Tuysuz, Beyhan and Bakircioglu, Mehmet and Choi, Murim and Delil, Sakir and {\c C}a{\u g}layan, Ahmet O and Baranoski, Jacob F and Erturk, Ozdem and Yalcinkaya, Cengiz and Karacorlu, Murat and Dincer, Alp and Johnson, Michele H and Mane, Shrikant and Chandra, Sreeganga S and Louvi, Angeliki and Boggon, Titus J and Lifton, Richard P and Horwich, Arthur L and G{\"u}nel, Murat} }