@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 {466, title = {A biallelic ANTXR1 variant expands the anthrax toxin receptor associated phenotype to tooth agenesis.}, journal = {Am J Med Genet A}, volume = {176}, year = {2018}, month = {2018 04}, pages = {1015-1022}, abstract = {

Tooth development is regulated by multiple genetic pathways, which ultimately drive the complex interactions between the oral epithelium and mesenchyme. Disruptions at any time point during this process may lead to failure of tooth development, also known as tooth agenesis (TA). TA is a common craniofacial abnormality in humans and represents the failure to develop one or more permanent teeth. Many genes and potentially subtle variants in these genes contribute to the TA phenotype. We report the clinical and genetic impact of a rare homozygous ANTXR1 variant (c.1312C>T), identified by whole exome sequencing (WES), in a consanguineous Turkish family with TA. Mutations in ANTXR1 have been associated with GAPO (growth retardation, alopecia, pseudoanodontia, and optic atrophy) syndrome and infantile hemangioma, however no clinical characteristics associated with these conditions were observed in our study family. We detected the expression of Antxr1 in oral and dental tissues of developing mouse embryos, further supporting a role for this gene in tooth development. Our findings implicate ANTXR1 as a candidate gene for isolated TA, suggest the involvement of specific hypomorphic alleles, and expand the previously known ANTXR1-associated phenotypes.

}, keywords = {Alleles, Amino Acid Substitution, Animals, Anodontia, Child, Consanguinity, Facies, Genetic Association Studies, Genotype, Humans, Male, Mice, Mutation, Neoplasm Proteins, Pedigree, Phenotype, Radiography, Receptors, Cell Surface, Whole Exome Sequencing}, issn = {1552-4833}, doi = {10.1002/ajmg.a.38625}, author = {Dinckan, Nuriye and Du, Renqian and Akdemir, Zeynep C and Bayram, Yavuz and Jhangiani, Shalini N and Doddapaneni, Harsha and Hu, Jianhong and Muzny, Donna M and Guven, Yeliz and Aktoren, Oya and Kayserili, H{\"u}lya and Boerwinkle, Eric and Gibbs, Richard A and Posey, Jennifer E and Lupski, James R and Uyguner, Zehra O and Letra, Ariadne} } @article {446, title = {WNT Signaling Perturbations Underlie the Genetic Heterogeneity of Robinow Syndrome.}, journal = {Am J Hum Genet}, volume = {102}, year = {2018}, month = {2018 01 04}, pages = {27-43}, abstract = {

Locus heterogeneity characterizes a variety of skeletal dysplasias often due to interacting or overlapping signaling pathways. Robinow syndrome is a skeletal disorder historically refractory to molecular diagnosis, potentially stemming from substantial genetic heterogeneity. All current known pathogenic variants reside in genes within the noncanonical Wnt signaling pathway including ROR2, WNT5A, and more recently, DVL1 and DVL3. However, \~{}70\% of autosomal-dominant Robinow syndrome cases remain molecularly unsolved. To investigate this missing heritability, we recruited 21 families with at least one family member clinically diagnosed with Robinow or Robinow-like phenotypes and performed genetic and genomic studies. In total, four families with variants in FZD2 were identified as well as three individuals from two families with biallelic variants in NXN that co-segregate with the phenotype. Importantly, both FZD2 and NXN are relevant protein partners in the WNT5A interactome, supporting their role in skeletal development. In addition to confirming that clustered -1 frameshifting variants in DVL1 and DVL3 are the main contributors to dominant Robinow syndrome, we also found likely pathogenic variants in candidate genes GPC4 and RAC3, both linked to the Wnt signaling pathway. These data support an initial hypothesis that Robinow syndrome results from perturbation of the Wnt/PCP pathway, suggest specific relevant domains of the proteins involved, and reveal key contributors in this signaling cascade during human embryonic development. Contrary to the view that non-allelic genetic heterogeneity hampers gene discovery, this study demonstrates the utility of rare disease genomic studies to parse gene function in human developmental pathways.

}, keywords = {Adolescent, Adult, Base Sequence, Child, Child, Preschool, Chromosome Segregation, Craniofacial Abnormalities, Diagnosis, Differential, Dwarfism, Female, Genes, Dominant, Genetic Association Studies, Genetic Heterogeneity, Humans, Limb Deformities, Congenital, Male, Middle Aged, Mutation, Missense, Phenotype, Urogenital Abnormalities, Wnt Signaling Pathway}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.10.002}, author = {White, Janson J and Mazzeu, Juliana F and Coban-Akdemir, Zeynep and Bayram, Yavuz and Bahrambeigi, Vahid and Hoischen, Alexander and van Bon, Bregje W M and Gezdirici, Alper and Gulec, Elif Yilmaz and Ramond, Francis and Touraine, Renaud and Thevenon, Julien and Shinawi, Marwan and Beaver, Erin and Heeley, Jennifer and Hoover-Fong, Julie and Durmaz, Ceren D and Karabulut, Halil Gurhan and Marzioglu-Ozdemir, Ebru and Cayir, Atilla and Duz, Mehmet B and Seven, Mehmet and Price, Susan and Ferreira, Barbara Merfort and Vianna-Morgante, Angela M and Ellard, Sian and Parrish, Andrew and Stals, Karen and Flores-Daboub, Josue and Jhangiani, Shalini N and Gibbs, Richard A and Brunner, Han G and Sutton, V Reid and Lupski, James R and Carvalho, Claudia M B} } @article {181, title = {Exome sequencing identifies a homozygous C5orf42 variant in a Turkish kindred with oral-facial-digital syndrome type VI.}, journal = {Am J Med Genet A}, volume = {167A}, year = {2015}, month = {2015 Sep}, pages = {2132-7}, abstract = {

Oral-facial-digital syndrome type VI (OFDVI) is a rare ciliopathy in the spectrum of Joubert syndrome (JS) and distinguished from other oral-facial-digital syndromes by metacarpal abnormalities with central polydactyly and by a molar tooth sign on cranial MRI. Additional characteristic features include short stature, micrognathia, posteriorly rotated low-set ears, hypertelorism, epicanthal folds, broad nasal tip, tongue hamartoma, upper lip notch, intraoral frenula, cleft lip/palate, and renal anomalies. Recently, novel mutations in C5orf42 were identified in 9 out of 11 OFDVI families. In a subsequent study C5orf42 was found to be mutated in only 2 out of 17 OFDVI probands while 28 patients with a pure JS phenotype also had pathogenic mutations of C5orf42. We report on two affected cousins diagnosed with OFDVI who were born from first degree cousin marriages. Whole exome sequencing (WES) identified a homozygous predicted damaging missense mutation (c.4034A > G; p.Gln1345Arg) in the C5orf42 gene. Our data contribute to the evidence that C5orf42 is one of the causative genes for OFDVI.

}, keywords = {Abnormalities, Multiple, Cerebellar Diseases, Cerebellum, Child, Cleft Palate, Exome, Eye Abnormalities, Female, Genetic Predisposition to Disease, Hamartoma, Homozygote, Humans, Kidney Diseases, Cystic, Magnetic Resonance Imaging, Male, Membrane Proteins, Middle Aged, Mutation, Orofaciodigital Syndromes, Phenotype, Retina, Turkey}, issn = {1552-4833}, doi = {10.1002/ajmg.a.37092}, author = {Bayram, Yavuz and Aydin, Hatip and Gambin, Tomasz and Akdemir, Zeynep Coban and Atik, Mehmed M and Karaca, Ender and Karaman, Ali and Pehlivan, Davut and Jhangiani, Shalini N and Gibbs, Richard A and Lupski, James R} } @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} }