Mutation analysis in the family of a Taiwanese boy with with epidermolysis bullosa simplex Dowling-Meara

Epidermolysis bullosa simplex (EBS) is a group of hereditary bullous diseases characterized by intraepidermal blistering due to mechanical stress-induced degeneration of basal keratinocytes. The major subtypes of EBS, including EBS Dowling-Meara (EBS-DM), are caused by mutations of the basal keratin genes, keratin 5 (KRT5) or keratin 14 (KRT14). Here, we describe the first reported pedigree of EBS-DM in Taiwan. The proband was a 5-day-old newborn, who presented with numerous blisters of various sizes, some of which were hemorrhagic, as well as erosions on the extremities and hard palate since birth. Biopsy of a new vesicle showed subepidermal and basal cleavage with infiltration of eosinophils and neutrophils. Electron microscopy revealed cytolysis of basal cells and clumping of tonofilaments forming thick bundles and peculiar electron-dense round or oval basket-weave bodies. These features are characteristic of EBS-DM. The proband's mother had also suffered from a similar blistering disorder since birth, with gradual appearance of mottled pigmentation on the trunk, diffuse irregular or linear palmoplantar hyperkeratosis, and nail dystrophy. Mutation analysis revealed a heterozygous point mutation (R125C) in helix 1A of keratin 14 in the proband and his mother. The detection of this pathogenic point mutation enables future prenatal diagnosis in this family.