Epidermolysis Bullosa Dystrophica (RDEB) is a rare autosomal recessive disorder characterized by tissue separation, which occurs below the dermal-epidermal basement membrane at the level of the anchoring fibrils. Growth retardation is observed at an early age as well as in adults. Symptoms include fusion of all fingers and toes into mitten-like deformity, and esophageal and anal stenoses. Eye disorders are also common. There are different clinical types based on severity, ranging from severe mutilating forms to mild forms with limited and localized scarring, and less frequent extracutaneous manifestations. Mild forms include epidermolysis bullosa mitis and epidermolysis bullosa localisata. The most severe and classic form is known as the Hallopeau-Siemens type (RDEB-HS). Patients with this disorder develop aggressive cutaneous squamous cell carcinoma (cSCC).
Epidermolysis Bullosa Dystrophica is caused by mutation in the COL7A1 gene on chromosome 3p21.31. COL7A1 encodes an important component required for the proper assembly of type VII collagen, which plays an essential role in strengthening and stabilizing the skin. Additionally, a defect in a functional SNP in the MMP1 gene, which results in increased collagenase activity, is associated with determining the severity of the Epidermolysis Bullosa Dystrophica disease. The plausible explanation for this observation could be that MMP1 acts as a modifier gene in RDEB.