Baylor Genetics Featured in Genetics in Medicine Journal for Study on Autosomal Recessive Genetic Diseases

CNVs cause autosomal recessive genetic diseases with or without involvement of SNV/indels

Yuan B; Wang L; Liu P; Shaw C; Dai H; Cooper L; Zhu W; Anderson SA; Meng L; Wang X; Wang Y; Xia F; Xiao R; Braxton A; Peacock S; Schmitt E; Ward PA; Vetrini F; He W; Chiang T; Muzny D; Gibbs RA; Beaudet AL; Breman AM; Smith J; Cheung SW; Bacino CA; Eng CM; Yang Y; Lupski JR; Bi W

Published: June 24, 2020

Abstract

Purpose

Improved resolution of molecular diagnostic technologies enabled detection of smaller sized exonic level copy-number variants (CNVs). The contribution of CNVs to autosomal recessive (AR) conditions may be better recognized using a large clinical cohort.

Methods

We retrospectively investigated the CNVs’ contribution to AR conditions in cases subjected to chromosomal microarray analysis (CMA, N = ~70,000) and/or clinical exome sequencing (ES, N = ~12,000) at Baylor Genetics; most had pediatric onset neurodevelopmental disorders.

Results

CNVs contributed to biallelic variations in 87 cases, including 81 singletons and three affected sibling pairs. Seventy cases had CNVs affecting both alleles, and 17 had a CNV and a single-nucleotide variant (SNV)/indel in trans. In total, 94.3% of AR-CNVs affected one gene; among these 41.4% were single-exon and 35.0% were multiexon partial-gene events. Sixty-nine percent of homozygous AR-CNVs were embedded in homozygous genomic intervals. Five cases had large deletions unmasking an SNV/indel on the intact allele for a recessive condition, resulting in multiple molecular diagnoses.

Conclusions

AR-CNVs are often smaller in size, transmitted through generations, and underrecognized due to limitations in clinical CNV detection methods. Our findings from a large clinical cohort emphasized integrated CNV and SNV/indel analyses for precise clinical and molecular diagnosis especially in the context of genomic disorders.

Genetics in Medicine (2020)

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