Dystrophic Epidermolysis Bullosa (COL7A1)
Dystrophic epidermolysis bullosa is an autosomal recessive pan-ethnic disorder caused by pathogenic variants in the gene COL7A1. Predominant clinical features include blistering and scarring. In the most severe forms, the blistering may be present at birth or early infancy and may affect the whole body. Healing and scarring of digits can result in their fusion; likewise, scarring of the mouth, tongue and esophagus can result in feeding difficulties. Less severe forms may have blistering confined to certain areas of the body. The lifetime risk of developing squamous cell carcinoma is very high. Life expectancy is variable; severely affected infants are at risk for fatal sepsis, and the risk of malignancy in adulthood may also reduce life expectancy. Genotype-phenotype correlations have been observed; the most severely affected individuals tend to have two null variants, whereas patients with some residual protein appear to have milder disease. Alleles with glycine substitutions tend to be more severe than other missense variants.
For information about carrier frequency and residual risk, please see the Expanded Carrier Screen brochure.