A novel homozygous splice site mutation in COL7A1 in a Chinese patient with severe recessive dystrophic epidermolysis bullosa and squamous cell carcinoma.

BACKGROUND: Recessive dystrophic epidermolysis bullosa (RDEB) is an inherited blistering skin disorder caused by mutations in COL7A1 gene encoding type VII collagen, the major component of anchoring fibrils in the dermo-epidermal junction. The development of cutaneous squamous cell carcinoma (SCC) is one of the most serious complications of this disease. We report herein a Chinese patient with the severe generalized subtype of RDEB (RDEB-sev gen) complicated by SCC.

METHODS: Skin biopsies were examined for histology, basement membrane ultrastructure, and type VII collagen expression. Genomic DNA was extracted from the peripheral blood samples and subjected to polymerase chain reaction amplification and direct automated DNA sequencing.

RESULTS: Histopathological examination of the patient's skin revealed an undetectable expression of type VII collagen polypeptides in the basement membrane zone. Mutation analysis identified a novel splice site mutation in intron 64 (IVS64+5g->a) of COL7A1 gene, which resulted in an in-frame deletion of exon 64 in both alleles.

CONCLUSIONS: This report contributes to the expanding database of COL7A1 mutations and emphasizes the need to elucidate the underlying genetic mechanisms associated with the increased incidence of SCC in RDEB patients.