Mutation Analyses of COL7A1 Gene in Three Taiwanese Patients with Severe Recessive Dystrophic Epidermolysis Bullosa

Abstract

Dystrophic epidermolysis bullosa (DEB) is a hereditary mechanobullous disorder characterized by fragility of the skin and mucous membranes caused by abnormal anchoring fibrils. Both dominant and recessive DEB are caused by mutations in COL7A1, the gene encoding type VII collagen, the major component of anchoring fibrils. We performed mutation analysis of COL7A1 in three patients with recessive DEB. The diagnosis of DEB was based on the characteristic clinical features and confirmed histopathologically. All 118 exons and flanking intron boundaries of COL7A1 were amplified. Four novel mutations (3373insGG, 7769delG, E1535X, G2061E) and two potential splicing mutations were detected. The first three of these mutations resulted in premature termination codons, while G2061E caused a glycine substitution mutation in the triple-helical domain. This is the first report of mutation analyses of the COL7A1 gene in Taiwanese pedigrees with recessive DEB. Each patient had a heterozygous premature termination codon mutation combined with either a glycine substitution mutation in the critical triple-helical collagenous domain or a potential splicing mutation. These genotypes correlate well with the severe clinical phenotype of recessive DEB.