Characterization of mutations of the type VII collagen gene (COL7A1) in recessive dystrophic epidermolysis bullosa mitis (M-RDEB) from three Korean patients

In recent years, the molecular basis for the main subtypes of epidermolysis bullosa (EB) has been elucidated with pathogenetic mutations delineated in tell different genes encoding structural components of the dermal-epiderma l junction. Both the autosomal dominant and recessive forms of dystrophic E B (DEB) is caused by mutations in the COL7A1 gene. Type VII collagen is a m ajor component of anchoring fibrils, structural elements that stabilize the attachment of the basement membrane to underlying dermis. Recent delineati on of the exon-intron organization of the COL7A1 gene provided the basis fo r the comprehensive design of PCR primer Fairs that amplified exons in geno mic DNA by placing the primers on the flanking introns. A number of COL7A1 mutations have been reported and some genotype phenotype correlations are s tarting to emerge. In this study, we examined mutational analyses from thre e Korean patients with recessive dystrophic EB (RDEB) mitis. We designed an d optimized primers according to the previously reported sequences. Such PC R amplification products can be examined by electrophoretic scanning techni que, CSGE heteroduplex analyses. Utilizing heteroduplex analyses, we have i dentified a number of sequence variants in COL7A1 both in unaffected indivi duals and in patients with M-RDEB. Mutation detection of the COL7A1 gene re vealed six allelic mutations (V6677E, P6685S, Y3749S, P6084S, P6695R and G6 697C). We suggest that the full length of type VII collagen polypeptide are synthesized, but those missense mutations, that may affect a critical amin o acid, can alter the conformation of the protein and interferes with the a ssembly and packing of type VII collagen molecules into anchoring fibrils. Immunohistochemical study of skin biopsies by use of anti-type VII collagen antibody showed markedly reduced staining and presence of a dermo/epiderma l cleavage. This is the first report of a COL7A1 mutation study in DEB from Korean patients. We hope that these data contribute to the expanding datab ase on COL7A1 mutations in dystrophic epidermolysis bullosa, and further il lustrate the extensive diversity of mutational events that led to the RDEB phenotype. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.