Diagnostic dilemma of "sporadic" cases of dystrophic epidermolysis bullosa: a new dominant or mitis recessive mutation?

Dystrophic forms of epidermolysis bullosa (DEB), characterized by mutations in the type VII collagen gene (COL7A1), are inherited either in an autosomal dominant or autosomal recessive fashion, and sporadic, de novo cases have also been reported. Clinically, the dominant forms (DDEB) can be indistinguishable from the mild, mitis forms of recessively inherited DEB (M-RDEB). This situation poses a dilemma in case of families with 1 mildly affected individual and clinically normal parents: Is it a new dominant or mitis recessive DEB? In this study we review 2 cases with mild DEB, the parents being clinically normal. One of the cases was shown to be a compound heterozygote for 2 silent missense mutations (R2063W/G2366S), thus being diagnosed as M-RDEB. The second case had a single glycine substitution mutation (G2079E) in COL7A1 and had therefore DDEB. These findings have implications for the genetic counseling of these families concerning the risk of recurrence of the disease in subsequent pregnancies in the present and future generations.