RESUMEN
BACKGROUND: Previous research in autism and other neurodevelopmental disorders (NDDs) has indicated an important contribution of protein-coding (coding) de novo variants (DNVs) within specific genes. The role of de novo noncoding variation has been observable as a general increase in genetic burden but has yet to be resolved to individual functional elements. In this study, we assessed whole-genome sequencing data in 2671 families with autism (discovery cohort of 516 families, replication cohort of 2155 families). We focused on DNVs in enhancers with characterized in vivo activity in the brain and identified an excess of DNVs in an enhancer named hs737. RESULTS: We adapted the fitDNM statistical model to work in noncoding regions and tested enhancers for excess of DNVs in families with autism. We found only one enhancer (hs737) with nominal significance in the discovery (p = 0.0172), replication (p = 2.5 × 10-3), and combined dataset (p = 1.1 × 10-4). Each individual with a DNV in hs737 had shared phenotypes including being male, intact cognitive function, and hypotonia or motor delay. Our in vitro assessment of the DNVs showed they all reduce enhancer activity in a neuronal cell line. By epigenomic analyses, we found that hs737 is brain-specific and targets the transcription factor gene EBF3 in human fetal brain. EBF3 is genome-wide significant for coding DNVs in NDDs (missense p = 8.12 × 10-35, loss-of-function p = 2.26 × 10-13) and is widely expressed in the body. Through characterization of promoters bound by EBF3 in neuronal cells, we saw enrichment for binding to NDD genes (p = 7.43 × 10-6, OR = 1.87) involved in gene regulation. Individuals with coding DNVs have greater phenotypic severity (hypotonia, ataxia, and delayed development syndrome [HADDS]) in comparison to individuals with noncoding DNVs that have autism and hypotonia. CONCLUSIONS: In this study, we identify DNVs in the hs737 enhancer in individuals with autism. Through multiple approaches, we find hs737 targets the gene EBF3 that is genome-wide significant in NDDs. By assessment of noncoding variation and the genes they affect, we are beginning to understand their impact on gene regulatory networks in NDDs.
Asunto(s)
Trastorno Autístico/genética , Predisposición Genética a la Enfermedad , Hipotonía Muscular/genética , Trastornos del Neurodesarrollo/genética , Factores de Transcripción/genética , Trastorno Autístico/epidemiología , Trastorno Autístico/patología , Elementos de Facilitación Genéticos/genética , Exoma/genética , Femenino , Redes Reguladoras de Genes/genética , Humanos , Masculino , Hipotonía Muscular/epidemiología , Hipotonía Muscular/patología , Mutación/genética , Trastornos del Neurodesarrollo/epidemiología , Trastornos del Neurodesarrollo/patología , Neuronas/metabolismo , Neuronas/patologíaRESUMEN
De novo germline mutations in GNB1 have been associated with a neurodevelopmental phenotype. To date, 28 patients with variants classified as pathogenic have been reported. We add 18 patients with de novo mutations to this cohort, including a patient with mosaicism for a GNB1 mutation who presented with a milder phenotype. Consistent with previous reports, developmental delay in these patients was moderate to severe, and more than half of the patients were non-ambulatory and nonverbal. The most observed substitution affects the p.Ile80 residue encoded in exon 6, with 28% of patients carrying a variant at this residue. Dystonia and growth delay were observed more frequently in patients carrying variants in this residue, suggesting a potential genotype-phenotype correlation. In the new cohort of 18 patients, 50% of males had genitourinary anomalies and 61% of patients had gastrointestinal anomalies, suggesting a possible association of these findings with variants in GNB1. In addition, cutaneous mastocytosis, reported once before in a patient with a GNB1 variant, was observed in three additional patients, providing further evidence for an association to GNB1. We will review clinical and molecular data of these new cases and all previously reported cases to further define the phenotype and establish possible genotype-phenotype correlations.
Asunto(s)
Subunidades beta de la Proteína de Unión al GTP/genética , Estudios de Asociación Genética , Mutación/genética , Adolescente , Niño , Preescolar , Estudios de Cohortes , Epilepsia/genética , Femenino , Subunidades beta de la Proteína de Unión al GTP/química , Humanos , Masculino , Sistema Nervioso/crecimiento & desarrollo , Fenotipo , Embarazo , Estructura Terciaria de ProteínaRESUMEN
The contribution of human subtelomeric DNA and chromatin organization to telomere integrity and chromosome end protection is not yet understood in molecular detail. Here, we show by ChIP-Seq that most human subtelomeres contain a CTCF- and cohesin-binding site within â¼1-2 kb of the TTAGGG repeat tract and adjacent to a CpG-islands implicated in TERRA transcription control. ChIP-Seq also revealed that RNA polymerase II (RNAPII) was enriched at sites adjacent to the CTCF sites and extending towards the telomere repeat tracts. Mutation of CTCF-binding sites in plasmid-borne promoters reduced transcriptional activity in an orientation-dependent manner. Depletion of CTCF by shRNA led to a decrease in TERRA transcription, and a loss of cohesin and RNAPII binding to the subtelomeres. Depletion of either CTCF or cohesin subunit Rad21 caused telomere-induced DNA damage foci (TIF) formation, and destabilized TRF1 and TRF2 binding to the TTAGGG proximal subtelomere DNA. These findings indicate that CTCF and cohesin are integral components of most human subtelomeres, and important for the regulation of TERRA transcription and telomere end protection.