Explore the vast range of titles available.

Perinatal stroke is associated with significant short- and long-term morbidity and has been recognized as the most common cause of cerebral palsy in term infants. The diagnosis of presumed perinatal stroke (PPS) is made in children who present with neurological deficit and/or seizures attributable to focal chronic infarction on neuroimaging and have uneventful neonatal history. The underlying mechanism of presumed perinatal stroke remains unknown and thorough investigation of potential monogenic causes has not been conducted to date. Here, we describe the use of untargeted exome sequencing to investigate a cohort of eight patients from six families with PPS. A likely deleterious variant was identified in four families. These include the well-established risk genes COL4A2 and JAM3. In addition, we report the first independent confirmation of the recently described link between ESAM and perinatal stroke. Our data also highlight NID1 as a candidate gene for the condition. This study suggests that monogenic disorders are important contributors to the pathogenesis of PPS and should be investigated by untargeted sequencing especially when traditional risk factors are excluded.

Background Osteogenesis imperfecta (OI) is an hereditary bone disease in which increased bone fragility leads to frequent fractures and other complications, usually in an autosomal dominant fashion. An expanding list of genes that encode proteins related to collagen metabolism are now recognised as important causes of autosomal recessive (AR) OI. Our aim was to study the contribution of known genes to AR OI in order to identify novel loci in mutation-negative cases. Methods We enrolled multiplex consanguineous families and simplex cases (also consanguineous) in which mutations in COL1A1 and COL1A2 had been excluded. We used autozygome guided mutation analysis of AR OI (AR OI) genes followed by exome sequencing when such analysis failed to identify the causative mutation. Results Two simplex and 11 multiplex families were enrolled, encompassing 27 cases. In three multiplex families, autozygosity and linkage analysis revealed a novel recessive OI locus on chromosome 9q31.1-31.3, and a novel truncating deletion of exon 4 of TMEM38B was identified within that interval. In addition, gonadal or gonadal/somatic mosaic mutations in COL1A1 or COL1A2 and homozygous mutations in recently described AR OI genes were identified in all remaining families. Conclusions TMEM38B is a novel candidate gene for AR OI. Future studies are needed to explore fully the contribution of this gene to AR OI in other populations.

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.

ObjectiveTo investigate the utility of autozygome analysis and exome sequencing in a cohort of patients with suspected or confirmed mitochondrial encephalomyopathy.MethodsAutozygome was used to highlight candidate genes for direct sequencing in 10 probands, all born to consanguineous parents. Autozygome was also used to filter the variants from exome sequencing of four probands.ResultsIn addition to revealing mutations in known mitochondrial genes, the analysis revealed the identification of two novel candidate disease genes: MFF and FARS2, encoding the mitochondrial fission factor and phenylalanyl-tRNA synthetase, respectively.InterpretationThese findings expand the repertoire of genes that are mutated in patients with mitochondrial disorders and highlight the value of integrating genomic approaches in the evaluation of these patients.

Background Numerous syndromic forms of intellectual disability have been described including those with abnormal sweating pattern. Purpose To describe the clinical and molecular analysis of a large multiplex consanguineous Saudi family with an unusual constellation of severe intellectual disability, hypohidrosis, abnormal teeth, and acquired microcephaly. Methods Clinical evaluation, autozygosity mapping, exome sequencing, and expression analysis. Results Autozygosity mapping revealed a single critical locus corresponding to chr13:39 338 062–40 857 430. Exome sequencing uncovered a deep intronic (NM_020751.2:c.1167–24A>G) variant in COG6 that largely replaces the consensus acceptor site, resulting in pronounced reduction of the normal transcript and consequent deficiency of COG6 protein. Patient cells also exhibited pronounced deficiency of STX6, consistent with the established stabilising effect of COG6 on STX6. Four additional patients representing two families of the same tribal origin as the original family were found to have the same mutation, confirming a founder effect. Remarkably, none of the patients displayed any detectable abnormality in the glycosylation pattern of transferrin, which contradicts a previously published report of a patient whose abnormal glycosylation pattern was presumed to be caused by a missense variant in COG6. Conclusions Our data implicate COG6 in the pathogenesis of a novel hypohidrotic disorder in humans that is distinct from congenital disorders of glycosylation.

Ehlers–Danlos syndrome (EDS) describes a group of clinical entities in which the connective tissue, primarily that of the skin, joint and vessels, is abnormal, although the resulting clinical manifestations can vary widely between the different historical subtypes. Many cases of hereditary disorders of connective tissue that do not seem to fit these historical subtypes exist. The aim of this study is to describe a large series of patients with inherited connective tissue disorders evaluated by our clinical genetics service and for whom a likely causal variant was identified. In addition to clinical phenotyping, patients underwent various genetic tests including molecular karyotyping, candidate gene analysis, autozygome analysis, and whole-exome and whole-genome sequencing as appropriate. We describe a cohort of 69 individuals representing 40 families, all referred because of suspicion of an inherited connective tissue disorder by their primary physician. Molecular lesions included variants in the previously published disease genes B3GALT6 , GORAB , ZNF469 , B3GAT3 , ALDH18A1 , FKBP14 , PYCR1 , CHST14 and SPARC with interesting variations on the published clinical phenotypes. We also describe the first recessive EDS-like condition to be caused by a recessive COL1A1 variant. In addition, exome capture in a familial case identified a homozygous truncating variant in a novel and compelling candidate gene, AEBP1 . Finally, we also describe a distinct novel clinical syndrome of cutis laxa and marked facial features and propose ATP6V1E1 and ATP6V0D2 (two subunits of vacuolar ATPase) as likely candidate genes based on whole-genome and whole-exome sequencing of the two families with this new clinical entity. Our study expands the clinical spectrum of hereditary disorders of connective tissue and adds three novel candidate genes including two that are associated with a highly distinct syndrome.

To describe our experience with a large cohort (411 patients from 288 families) of various forms of skeletal dysplasia who were molecularly characterized. Detailed phenotyping and next-generation sequencing (panel and exome). Our analysis revealed 224 pathogenic/likely pathogenic variants (54 (24%) of which are novel) in 123 genes with established or tentative links to skeletal dysplasia. In addition, we propose 5 genes as candidate disease genes with suggestive biological links (WNT3A, SUCO, RIN1, DIP2C, and PAN2). Phenotypically, we note that our cohort spans 36 established phenotypic categories by the International Skeletal Dysplasia Nosology, as well as 18 novel skeletal dysplasia phenotypes that could not be classified under these categories, e.g., the novel C3orf17-related skeletal dysplasia. We also describe novel phenotypic aspects of well-known disease genes, e.g., PGAP3-related Toriello–Carey syndrome–like phenotype. We note a strong founder effect for many genes in our cohort, which allowed us to calculate a minimum disease burden for the autosomal recessive forms of skeletal dysplasia in our population (7.16E-04), which is much higher than the global average. By expanding the phenotypic, allelic, and locus heterogeneity of skeletal dysplasia in humans, we hope our study will improve the diagnostic rate of patients with these conditions.

Meckel-Gruber syndrome (MKS, OMIM #249000) is a multiple congenital malformation syndrome that represents the severe end of the ciliopathy phenotypic spectrum. Despite the relatively common occurrence of this syndrome among Arabs, little is known about its genetic architecture in this population. This is a series of 18 Arab families with MKS, who were evaluated clinically and studied using autozygome-guided mutation analysis and exome sequencing. We show that autozygome-guided candidate gene analysis identified the underlying mutation in the majority (n=12, 71%). Exome sequencing revealed a likely pathogenic mutation in three novel candidate MKS disease genes. These include C5orf42, Ellis-van-Creveld disease gene EVC2 and SEC8 (also known as EXOC4), which encodes an exocyst protein with an established role in ciliogenesis. This is the largest and most comprehensive genomic study on MKS in Arabs and the results, in addition to revealing genetic and allelic heterogeneity, suggest that previously reported disease genes and the novel candidates uncovered by this study account for the overwhelming majority of MKS patients in our population.

BackgroundDyggve–Melchior–Clausen syndrome (DMC) is a chondrodysplasia that bears significant phenotypic resemblance to mucopolysaccharidosis type IV (Morquio disease). Autosomal recessive mutations in DYM are known to cause this disease through its role in Golgi organisation and intracellular traffic, but genetic heterogeneity is suspected.MethodsA family with DMC and normal intellectual development underwent clinical evaluation followed by autozygosity mapping and exome sequencing. Immunoblot and immunofluorescence analyses were performed to characterise the effect of the mutation.ResultsThis multiplex consanguineous family links to a novel locus on 4q31.1. Exome sequencing revealed a missense mutation in RAB33B, which encodes a Rab protein with an established role in retrograde Golgi traffic. The mutation qualitatively replaces the invariant lysine residue in the guanine nucleotide-binding domain of this small GTPase protein and leads to marked protein deficiency, making it the likely causative mutation of DMC in this family.ConclusionThis study identifies a new DMC gene and highlights the role of intracellular traffic in the pathogenesis of this disease.

Background Meckel–Gruber syndrome (MKS) is a genetically heterogeneous severe ciliopathy characterised by early lethality, occipital encephalocele, polydactyly, and polycystic kidney disease. Purpose To report genetic analysis results in two families in which all known MKS diseases genes have been excluded. Methods In two consanguineous families with classical MKS in which autozygome-guided sequencing of previously reported MKS genes was negative, we performed exome sequencing followed by autozygome filtration. Results We identified one novel splicing mutation in TMEM231, which led to complete degradation of the mutant transcript in one family, and a novel missense mutation in the other, both in the homozygous state. Conclusions TMEM231 represents a novel MKS locus. The very recent identification of TMEM231 mutations in Joubert syndrome supports the growing appreciation of the overlap in the molecular pathogenesis between these two ciliopathies.