A common insertion mutation in COL7A1 in two Italian families with recessive dystrophic epidermolysis bullosa.

Recessive dystrophic epidermis bullosa is ultrastructurally characterized by the absence of anchoring fibrils, and genetic analyses have revealed that recessive dystrophic epidermolysis bullosa results from mutations in the type VII collagen gene (COL7A1). The mutations disclosed thus far are largely family specific, with no evidence for mutational hotspot(s). In this study, we report a recurrent premature termination codon mutation detected in two apparently unrelated Italian families in different regions of the country. This mutation, 497insA in exon 4 of COL7A1, was found in combination with two different premature termination codon mutations in these families. Haplotype analysis suggested a shared genetic background in the allele containing the mutation 497insA, suggesting that this genetic lesion may represent an ancestral mutation within the Italian gene pool.