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Background: With the increasing number of genomic sequencing studies, hundreds of genes have been implicated in neurodevelopmental disorders (NDDs). The rate of gene discovery far outpaces our understanding of genotype-phenotype correlations, with clinical characterization remaining a bottleneck for understanding NDDs. Most disease-associated Mendelian genes are members of gene families, and we hypothesize that those with related molecular function share clinical presentations., Methods: We tested our hypothesis by considering gene families that have multiple members with an enrichment of de novo variants among NDDs, as determined by previous meta-analyses. One of these gene families is the heterogeneous nuclear ribonucleoproteins (hnRNPs), which has 33 members, five of which have been recently identified as NDD genes (HNRNPK, HNRNPU, HNRNPH1, HNRNPH2, and HNRNPR) and two of which have significant enrichment in our previous meta-analysis of probands with NDDs (HNRNPU and SYNCRIP). Utilizing protein homology, mutation analyses, gene expression analyses, and phenotypic characterization, we provide evidence for variation in 12 HNRNP genes as candidates for NDDs. Seven are potentially novel while the remaining genes in the family likely do not significantly contribute to NDD risk., Results: We report 119 new NDD cases (64 de novo variants) through sequencing and international collaborations and combined with published clinical case reports. We consider 235 cases with gene-disruptive single-nucleotide variants or indels and 15 cases with small copy number variants. Three hnRNP-encoding genes reach nominal or exome-wide significance for de novo variant enrichment, while nine are candidates for pathogenic mutations. Comparison of HNRNP gene expression shows a pattern consistent with a role in cerebral cortical development with enriched expression among radial glial progenitors. Clinical assessment of probands (n = 188-221) expands the phenotypes associated with HNRNP rare variants, and phenotypes associated with variation in the HNRNP genes distinguishes them as a subgroup of NDDs., Conclusions: Overall, our novel approach of exploiting gene families in NDDs identifies new HNRNP-related disorders, expands the phenotypes of known HNRNP-related disorders, strongly implicates disruption of the hnRNPs as a whole in NDDs, and supports that NDD subtypes likely have shared molecular pathogenesis. To date, this is the first study to identify novel genetic disorders based on the presence of disorders in related genes. We also perform the first phenotypic analyses focusing on related genes. Finally, we show that radial glial expression of these genes is likely critical during neurodevelopment. This is important for diagnostics, as well as developing strategies to best study these genes for the development of therapeutics.

The Polycomb repressive complex 2 is an epigenetic writer and recruiter with a role in transcriptional silencing. Constitutional pathogenic variants in its component proteins have been found to cause two established overgrowth syndromes: Weaver syndrome (EZH2-related overgrowth) and Cohen-Gibson syndrome (EED-related overgrowth). Imagawa et al. (2017) initially reported a singleton female with a Weaver-like phenotype with a rare coding SUZ12 variant-the same group subsequently reported two additional affected patients. Here we describe a further 10 patients (from nine families) with rare heterozygous SUZ12 variants who present with a Weaver-like phenotype. We report four frameshift, two missense, one nonsense, and two splice site variants. The affected patients demonstrate variable pre- and postnatal overgrowth, dysmorphic features, musculoskeletal abnormalities and developmental delay/intellectual disability. Some patients have genitourinary and structural brain abnormalities, and there may be an association with respiratory issues. The addition of these 10 patients makes a compelling argument that rare pathogenic SUZ12 variants frequently cause overgrowth, physical abnormalities, and abnormal neurodevelopmental outcomes in the heterozygous state. Pathogenic SUZ12 variants may be de novo or inherited, and are sometimes inherited from a mildly-affected parent. Larger samples sizes will be needed to elucidate whether one or more clinically-recognizable syndromes emerge from different variant subtypes., (© 2019 Wiley Periodicals, Inc.)

Targeted whole-exome sequencing (WES) is a powerful diagnostic tool for a broad spectrum of heterogeneous neurological disorders. Here, we aim to examine the impact on diagnosis, treatment and cost with early use of targeted WES in early-onset epilepsy. WES was performed on 180 patients with early-onset epilepsy (≤5 years) of unknown cause. Patients were classified as Retrospective (epilepsy diagnosis >6 months) or Prospective (epilepsy diagnosis <6 months). WES was performed on an Ion Proton™ and variant reporting was restricted to the sequences of 620 known epilepsy genes. Diagnostic yield and time to diagnosis were calculated. An analysis of cost and impact on treatment was also performed. A molecular diagnoses (pathogenic/likely pathogenic variants) was achieved in 59/180 patients (33%). Clinical management changed following WES findings in 23 of 59 diagnosed patients (39%) or 13% of all patients. A possible diagnosis was identified in 21 additional patients (12%) for whom supporting evidence is pending. Time from epilepsy onset to a genetic diagnosis was faster when WES was performed early in the diagnostic process (mean: 145 days Prospective vs. 2,882 days Retrospective). Costs of prior negative tests averaged $8,344 per patient in the Retrospective group, suggesting savings of $5,110 per patient using WES. These results highlight the diagnostic yield, clinical utility and potential cost-effectiveness of using targeted WES early in the diagnostic workup of patients with unexplained early-onset epilepsy. The costs and clinical benefits are likely to continue to improve. Advances in precision medicine and further studies regarding impact on long-term clinical outcome will be important.

NBEA is a candidate gene for autism, and de novo variants have been reported in neurodevelopmental disease (NDD) cohorts. However, NBEA has not been rigorously evaluated as a disease gene, and associated phenotypes have not been delineated. We identified 24 de novo NBEA variants in patients with NDD, establishing NBEA as an NDD gene. Most patients had epilepsy with onset in the first few years of life, often characterized by generalized seizure types, including myoclonic and atonic seizures. Our data show a broader phenotypic spectrum than previously described, including a myoclonic-astatic epilepsy-like phenotype in a subset of patients. Ann Neurol 2018;84:796-803., (© 2018 American Neurological Association.)

Autism Spectrum Disorders (ASD) are complex neurodevelopmental conditions characterized by delays in social interactions and communication as well as displays of restrictive/repetitive interests. DNA copy number variants have been identified as a genomic susceptibility factor in ASDs and imply significant genetic heterogeneity. We report a 7-year-old female with ADOS-G and ADI-R confirmed autistic disorder harbouring a de novo 4 Mb duplication (18q12.1). Our subject displays severely deficient expressive language, stereotypic and repetitive behaviours, mild intellectual disability (ID), focal epilepsy, short stature and absence of significant dysmorphic features. Search of the PubMed literature and DECIPHER database identified 4 additional cases involving 18q12.1 associated with autism and/or ID that overlap our case: one duplication, two deletions and one balanced translocation. Notably, autism and ID are seen with genomic gain or loss at 18q12.1, plus epilepsy and short stature in duplication cases, and hypotonia and tall stature in deletion cases. No consistent dysmorphic features were noted amongst the reviewed cases. We review prospective ASD/ID candidate genes integral to 18q12.1, including those coding for the desmocollin/desmoglein cluster, ring finger proteins 125 and 138, trafficking protein particle complex 8 and dystrobrevin-alpha. The collective clinical and molecular features common to microduplication 18q12.1 suggest that dosage-sensitive, position or contiguous gene effects may be associated in the etiopathogenesis of this autism-ID-epilepsy syndrome., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Background: Fluconazole is a triazole antifungal used to treat mycotic infections. Fluconazole is reported to act as a teratogen when used continuously at a dosage of 400-800 mg daily. Fluconazole embryopathy was previously reported in 4 cases. The common features that were also seen in the current case include multiple synostosis (including craniosynostosis and digital synostosis), congenital heart defects, skeletal anomalies, and recognizable dysmorphic facial features., Case: We report the case of a 9-month-old male born to a 30-year-old woman following a 37-week pregnancy. The pregnancy was complicated by maternal human immunodeficiency virus (HIV) infection and multiple drug exposures, including fluconazole (400 mg/day) until the fifth month and then from 6 months to term, efavirenz, nevirapine, methadone, dapsone, pentamidine, and trimethoprim-sulfamethoxazole. At birth the infant had seizures related to neonatal abstinence syndrome and was noted to have multiple congenital anomalies. On examination at age 9 months, he had craniosynostosis secondary to coronal and lambdoidal suture closures, shallow orbital region, hypoplastic supraorbital ridges, hypertelorism, and mild ptosis. He had radioulnar synostosis and metacarpophalangeal-proximal interphalangeal symphalangism of D2-D5 bilaterally., Conclusions: The findings of cranial synostosis, multiple symphalangism, and long-bone abnormalities in our case are typical of other reported cases of fluconazole embryopathy. Our patient showed no evidence of embryopathy due to efavirenz, and he did not have the features of Antley-Bixler or other craniosynostosis syndromes. We review the literature regarding the teratogenic effects of prenatal exposure to fluconazole and provide additional evidence that prenatal fluconazole exposure has a clearly identifiable phenotype.

Williams-Beuren syndrome (WBS) results from a deletion of 7q11.23 in 90-95% of all clinically typical cases. Clinical manifestation can be variable and therefore, deletion size, inherited elastin (ELN) and LIM kinase 1 (LIMK1) alleles, gender, and parental origin of deletion have been investigated for associations with clinical outcome. In an analysis of 85 confirmed deletion cases, no statistically significant associations were found after Bonferroni's correction for multiple pairwise comparisons. Furthermore, the present data do not support presence of imprinted genes in the WBS common deletion despite a nonsignificant excess of maternal over paternal deletions. Maternal deletion cases were more likely to have a large head circumference in the present data. Also, pairwise comparisons between individual WBS clinical features have been conducted and revealed significant associations between (1) low birth weight and poor postnatal weight gain (<10th percentile at the time of examination) and (2) transient infantile hypercalcemia and a stellate iris pattern. The latter association could indicate a common underlying etiology., (Copyright 1999 Wiley-Liss, Inc.)

Partial duplications of chromosome 3 have previously been reported to have phenotypic characteristics similar to Brachmann-de Lange syndrome (BDLS). We present the case of a 13-year-old girl with an apparent duplication in the 3q25.1-->q26.1 region but none of the manifestations commonly seen in BDLS. The chromosome 3 duplication was confirmed with a FISH painting probe of the involved region. These results suggest that the region critical for Brachmann-de Lange syndrome is not within the duplicated region of 3q25.1-->q26.1.