377 A novel mutation of COL7A1 was identified in a Chinese pedigree of dystrophic epidermolysis bullosa with next-generation sequencing

Abstract

Traditional pathomorphological studies and Sanger sequencing of candidate genes of epidermolysis bullosa (EB) are expensive and laborious due to their clinical/genetic heterogeneity. Herein we reported 1 Chinese pedigree of dystrophic EB (DEB) and identified a novel mutation in COL7A1 with next-generation sequencing as an accurate, quick and cost-effective diagnosis strategy. A 35-year-old male presented to our department for recurrent bulla on the trunk, head, joints, hands, and feet since birth. The blisters progressed into ulcerations and healed with superficial atrophic scarring. Other abnormalities included dry curely hairs, shedding and atrophy of nails. Two of his brothers had similar but more severe presentations. Next-generation sequencing was performed under procedures as reported. Genomic DNA from the proband was fragmented, and the targeted exon sequences plus flanking sequences of the 10 known pathogenic genes of EB were specifically captured and enriched using array-based hybridization chip (NimbleGen, Madison, USA) followed by HiSeq2500 (Illumina, San Diego, USA) sequencing. The average coverage for all exons and adjacent intronic regions of these 10 genes (totally 66272bps) was 141.52×. Three variants were identified (COL7A1 c.4888C>T; COL7A1 c.4665_4667delinsCGG; ITGB4 c.264+8G>A) as candidates for further confirmation (Fig. 2a). Finally, the heterozygous variant of COL7A1 (c.4665_4667delinsCGG, p.Glu1555_Lys1556delinsAspGly) was co-segregated with the phenotypes. It was identified in all the 3 patients of this pedigree, but it was neither identified in other living members of this pedigree nor the 100 controls. This mutation was in the exon 47 of COL7A1 (p.Glu1555_Lys1556delinsAspGly) and was not reported before. The next-generation sequencing can cost- and time-effectively detect all known pathogenic genes as we showed, so it could be widely used in future.