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COL7A1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

COL7A1 gene

The COL7A1 gene is responsible for producing type VII collagen, a protein that acts as a vital anchor between the layers of the skin.

Normal Function

The COL7A1 gene provides instructions for making a protein called pro-α1(VII) chain that is used to assemble a larger protein called type VII collagen. Collagens are a family of proteins that strengthen and support connective tissues, such as skin, bone, tendons, and ligaments, throughout the body. In particular, type VII collagen plays an essential role in strengthening and stabilizing the skin.

Three pro-α1(VII) chains twist together to form a triple-stranded, ropelike molecule known as a procollagen. Cells release (secrete) procollagen molecules, and enzymes cut extra protein segments from the ends. Then the molecules arrange themselves into long, thin bundles of mature type VII collagen.

Type VII collagen is the major component of structures in the skin called anchoring fibrils. These fibrils are found in a region known as the epidermal basement membrane zone, which is a two-layer membrane located between the top layer of skin (the epidermis) and an underlying layer (the dermis). Anchoring fibrils hold the two layers of skin together by connecting the epidermal basement membrane to the dermis.

Health Conditions Related to Genetic Changes

Dystrophic epidermolysis bullosa

More than 700 mutations in the COL7A1 gene have been identified in people with dystrophic epidermolysis bullosa, a condition that causes the skin to be very fragile and to blister easily. These mutations alter the structure or disrupt the production of the pro-α1(VII) chain protein, which affects the production of type VII collagen. When type VII collagen is abnormal or missing, anchoring fibrils cannot form properly. A shortage of these fibrils impairs the connection of the epidermis to the dermis. As a result, friction or other minor trauma can cause the two skin layers to separate, leading to blisters and extensive scarring.

Researchers classify dystrophic epidermolysis bullosa into a few major types:

  • Recessive dystrophic epidermolysis bullosa (RDEB): Results from mutations in both copies of the COL7A1 gene. The most severe form, RDEB-sev gen, involves the production of abnormally short chains that cannot form type VII collagen, leading to extreme skin fragility.
  • Generalized and localized types (RDEB-gen and -loc): Caused by mutations that result in reduced or partially functional anchoring fibrils, leading to less severe symptoms.
  • Dominant dystrophic epidermolysis bullosa (DDEB): Results from mutations in one copy of the COL7A1 gene. These often affect the triple helical domain, where glycine is replaced by other amino acids, disrupting the collagen's structure and function.

It is unclear how COL7A1 gene mutations are associated with an increased risk of squamous cell carcinoma in people with dystrophic epidermolysis bullosa. Some research suggests that abnormal forms of type VII collagen may increase the risk of tumor formation, though other studies have not confirmed this association.

Other disorders

Mutations in the COL7A1 gene can also cause a rare condition called epidermolysis bullosa with congenital localized absence of skin (also known as Bart syndrome or aplasia cutis congenita type VI). Individuals with this condition have patches of missing skin at birth, typically on the legs, alongside the characteristic skin fragility and blistering of epidermolysis bullosa. Abnormal or absent fingernails and toenails are also common.

Genomic Location

The COL7A1 gene is found on chromosome 3.

Frequently Asked Questions

Yes. Significant advances have led to molecular therapies specifically targeting COL7A1 deficiency. An FDA-approved topical gene therapy, beremagene geperpavec (B-VEC), uses an engineered, non-replicating herpes simplex virus to deliver functional copies of the COL7A1 gene directly into open wounds during dressing changes. This enables local skin cells to synthesize normal type VII collagen and assemble functioning anchoring fibrils, significantly improving wound closure and durability. Systemic and cell-based gene correction strategies are also in active clinical development.
Because type VII collagen also supports the mucous membranes, severe COL7A1 mutations cause internal blistering throughout the digestive and urinary tracts. Key complications include esophageal blistering leading to strictures, dysphagia, and severe malnutrition; oral microstomia (reduced mouth opening) and tooth loss; corneal abrasions; chronic constipation from anal fissures; and chronic systemic microcytic anemia requiring iron infusions or blood transfusions due to blood loss through extensive open wounds.
Individuals with generalized severe RDEB have an extremely high lifetime risk of developing aggressive cutaneous squamous cell carcinoma (cSCC), often beginning in their twenties or thirties. Decades of chronic, non-healing open wounds, persistent local inflammation, and impaired tissue remodeling create a microenvironment prone to malignant cellular transformation. Because these tumors behave aggressively and metastasize early, regular, meticulous whole-body skin surveillance by an experienced dermatologist is critical, and any non-healing, raised, or hyperkeratotic lesions require prompt biopsy.
Both are caused by COL7A1 mutations, but recessive dystrophic epidermolysis bullosa (RDEB) is far more severe. In dominant DDEB, some functional type VII collagen is produced, leading to localized blistering primarily on hands, feet, knees, and elbows, along with nail dystrophy, usually without severe systemic complications. In severe generalized RDEB, anchoring fibrils are completely or largely absent, resulting in extensive, painful blistering over large body surfaces, mucosal involvement, fusion of fingers and toes (pseudosyndactyly or "mitten deformities"), and life-threatening complications.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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