Whole exome sequencing identified a novel compound heterozygous variation in COL7A1 gene causing dystrophic epidermolysis bullosa

Abstract

Dystrophic epidermolysis bullosa (DEB) is a series of severe genetic conditions affecting skin and nails caused by mutations in the COL7A1 gene. DEB has a strong phenotypic variability. In the present study, we recruited a case with a boy exhibiting typical DEB indication, and performed a clinical, genetic, and experimental investigation, followed by a prenatal diagnosis on their current pregnancy. Whole exome sequencing identified a novel compound heterozygous variation in COL7A1, consisting of two variants, namely c.191T>C (p.Leu64Pro) and c.5124G>A (p.Leu1708=) in the proband. In vitro study by minigene system indicated that c.5124G>A would result in an increased ratio of a transcript with exon-skipping, which supported its pathogenicity. Further prenatal detection confirmed the genotype-phenotye co-separation in this family. In conclusion, the findings in our study expanded the mutation spectrum of DEB, and emphasized the importance of paying attention to specific synonymous variants in the filtering process.

Keywords: COL7A1 gene; dystrophic epidermolysis bullosa; minigene system; whole exome sequencing.