Mutation in COL7A1 cause Dystrophic Epidermolysis Bullosa

More than 400 mutations in the COL7A1 gene cause Dystrophic Epidermolysis Bullosa [DEB]. These mutations alter the structure/disrupt the production of ‘type VII collagen’, which impairs the ability of anchoring fibrils to connect the epidermis to the dermis. When type VII collagen is abnormal or missing, anchoring fibrils cannot able to form properly. As a result, friction or other minor trauma can cause the two skin layers to separate. This separation leads to the formation of blisters, which results in extensive scarring as they heal.

The autosomal recessive types of dystrophic epidermolysis bullosa (RDEB) result from mutations in both copies of the COL7A1 gene in each cell. 

The most severe, classic form of this disorder is known as the ‘Hallopeau-Siemens type (RDEB-HS)’. Most of the COL7A1 mutations responsible for RDEB-HS significantly reduce or eliminate the production of type VII collagen. As a result, few or no anchoring fibrils are present to connect the epidermis with the dermis. This lack of anchoring fibrils causes the severe signs and symptoms of RDEB-HS. 

A to some extent less severe form of autosomal recessive dystrophic epidermolysis bullosa, known as the ‘non-Hallopeau-Siemens type (Non-HS RDEB)’, is caused by other types of mutations. These genetic changes allow a small amount of normal or partially functional type VII collagen to be produced.

Source: www.ghr.nlm.nih.gov