Epidermolysis bullosa simplex with mottled pigmentation: clinical aspects and confirmation of the P24L mutation in the KRT5 gene in further patients.

Epidermolysis bullosa simplex with mottled pigmentation (EBS-MP) is a rare dermatologic disorder of autosomal dominant inheritance with intraepidermal blistering after minor trauma, reticular hyperpigmentation unrelated to the blistering, nail dystrophy, and mild palmoplantar keratosis. Keratin 5 and keratin 14 are known to be essential for the basal keratinocyte cytoskeleton and are defective in several forms of epidermolysis bullosa simplex. Recently, a 71C-->T transition in the keratin 5 gene (KRT5) causing a P24L substitution was identified in some patients with EBS-MP. We present a family with three affected members and a sporadic patient with EBS-MP. They exemplify clinically mild expression with intrafamilial variability and the possibility of improvement with time. In all of them, mutation analysis of the KRT5 gene showed the P24L mutation. So far, other mutations in the same or in other genes have not been reported in patients with EBS-MP.