Bart's syndrome. Ultrastructure and genetic linkage.
BACKGROUND AND DESIGN: Bart's syndrome, originally described in a large family in 1966, consists of congenital localized absence of skin, blistering, and associated nail abnormalities. Since then, several descriptions of patients with similar clinical findings have suggested that this syndrome may represent any of the three subtypes of epidermolysis bullosa: epidermal, junctional, or dermal. Because no histologic or ultrastructural studies were done in Bart's kindred, and neither immunohistologic nor genetic linkage technology was available at that time, classification of the syndrome has been unclear. We report the findings of clinical, ultrastructural, immunohistologic, and genetic linkage studies of the original kindred and their descendants. We contacted original family members and their descendants by telephone and questionnaire. Skin biopsy specimens adjacent to blisters were obtained for ultrastructural and immunochemical analysis. Blood samples were drawn from affected members and their spouses and children for genetic linkage studies. RESULTS: The clinical findings seen in the descendants of the original family with Bart's syndrome were similar to those described in 1966. We did, however, detect persistence of blistering into adult life and mild atrophic scarring and milia formation at sites of blistering in some family members, a finding not noted in the original study. Hypertrophic scarring and albopapuloid lesions were not detected. Ultrastructural analysis of skin from affected family members showed poorly formed anchoring fibrils and cleavage below the lamina densa. Immunohistochemical staining localized type IV collagen at the roof of blistered skin. Staining for type VII collagen was found to have a normal distribution in nonblistered skin. Genetic linkage studies mapped the gene for the disease in this family to chromosome 3p at or near the site of the gene encoding type VII collagen. CONCLUSION: Bart's syndrome is a subtype of dominantly inherited dystrophic epidermolysis bullosa.