Non-coding variants are a rare cause of recessive developmental disorders in trans with coding variants.

Genetics in medicine : official journal of the American College of Medical Genetics
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Abstract

PURPOSE: Identifying pathogenic non-coding variants is challenging. A single protein-altering variant is often identified in a recessive gene in individuals with developmental disorders (DD), but the prevalence of pathogenic non-coding 'second hits' in trans with these is unknown.METHODS: In 4,073 genetically undiagnosed rare disease trio probands from the 100,000 Genomes project, we identified rare heterozygous protein-altering variants in recessive DD-associated genes. We identified rare non-coding variants on the other haplotype in introns, untranslated regions (UTRs), promoters, and candidate enhancer regions. We clinically evaluated the top candidates for phenotypic fit, and performed functional testing where possible.RESULTS: We identified 3,761 rare heterozygous loss-of-function or ClinVar pathogenic variants in recessive DD-associated genes in 2,430 probands. For 1,366 (36.3%) of these, we identified at least one rare non-coding variant in trans. Bioinformatic filtering and clinical review, revealed seven to be a good clinical fit. After detailed characterisation, we identified likely diagnoses for three probands (in GAA, NPHP3, and PKHD1) and candidate diagnoses in a further three (PAH, LAMA2, IGHMBP2).CONCLUSION: We developed a systematic approach to uncover new diagnoses involving compound heterozygous coding/non-coding variants and conclude that this mechanism is likely to be a rare cause of DDs.

Year of Publication
2024
Journal
Genetics in medicine : official journal of the American College of Medical Genetics
Pages
101249
Date Published
09/2024
ISSN
1530-0366
DOI
10.1016/j.gim.2024.101249
PubMed ID
39243181
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