Type VII collagen DNA linkage analysis in a Japanese family with dominant dystrophic epidermolysis bullosa.

Type VII collagen, a major component of anchoring fibrils in the basement membrane zone, is now considered to be a primary genetic factor in the pathogenesis of dominant dystrophic epidermolysis bullosa (DDEB). In this study, we performed genetic linkage analysis in a Japanese family with DDEB using a PvuII polymorphism in the type VII collagen gene. The pedigree consisted of 10 affected and 13 unaffected living individuals and was diagnosed as having Cockayne-Touraine type of DDEB. Electron microscopic examination of the skin demonstrated a diminished number and rudimentary structure of anchoring fibrils. PCR-based detection of PvuII polymorphism resulted in 3 genotypes and co-segregated with DDEB phenotype in this pedigree. The maximum lod score was 2.10 at recombination fraction (theta) of 0. The absence of recombination between DDEB and type VII collagen gene locus, as well as the observation of altered anchoring fibrils, suggested that type VII collagen is a candidate gene for the Japanese family with DDEB, although the lod score was statistically not significant.