Compound heterozygosity for a dominant glycine substitution and a recessive internal duplication mutation in the type XVII collagen gene results in junctional epidermolysis bullosa and abnormal dentition.
Junctional epidermolysis bullosa is a heterogeneous autosomal recessively inherited blistering skin disorder associated with fragility at the dermal-epidermal junction. Previously, mutations in this condition have been described in the three genes for the anchoring filament protein laminin 5 (LAMA3, LAMB3, and LAMC2), in the gene encoding the hemidesmosome-associated beta4 integrin (ITGB4), and in the gene for the hemidesmosomal protein type XVII collagen (COL17A1/BPAG2). In this study, we report a patient with a form of junctional epidermolysis bullosa with skin fragility and dental anomalies who is a compound heterozygote for a novel combination of mutations, ie, a glycine substitution mutation in one allele and an internal duplication in the other allele of COL17A1. The patient also has two offspring, both of whom have inherited the glycine substitution mutation, whereas the other COL17A1 allele is normal. The latter individuals show no evidence of skin fragility but have marked dental abnormalities with enamel hypoplasia and pitting. The clinical phenotype of junctional epidermolysis bullosa in the proband in this family probably arises due to a combination of the glycine substitution and the internal duplication in COL17A1, whereas the dental abnormalities of her offspring may be the result of the glycine substitution in COL17A1 alone, resulting in this dominantly inherited clinical phenotype.