Dystrophic epidermolysis bullosa

Alternate names

DEB; Epidermolysis bullosa dystrophica; Dermolytic epidermolysis bullosa; Epidermolysis bullosa, dermolytic

Definition

Dystrophic epidermolysis bullosa (DEB) is one of the major forms of epidermolysis bullosa.

Summary

Epidermolysis bullosa cause the skin to be very fragile and to blister easily. Blisters and skin erosions form in response to minor injury or friction, such as rubbing or scratching.

Cause

• DEB is caused by changes (mutations) in the COL7A1 gene.
• This gene provides instructions for making a protein that forms the pieces (subunits) of a larger protein called type VII collagen.
• Type VII collagen plays an important role in strengthening and stabilizing the skin.
• It is the main component of structures called anchoring fibrils, which anchor the top layer of skin, called the epidermis, to an underlying layer called the dermis.

Gene mutations

• COL7A1 gene mutations alter the structure or disrupt the production of the type VII collagen subunit protein.
• These changes affect the production of type VII collagen.
• A shortage of these fibrils disrupts the connection of the epidermis to the dermis, and friction or other minor trauma can cause the two skin layers to separate.
• This separation leads to the formation of blisters, which can cause extensive scarring as they heal.

Types

• DEB is divided into two major types depending on inheritance pattern: recessive dystrophic epidermolysis bullosa (RDEB) and dominant dystrophic epidermolysis bullosa (DDEB).
• Each type is further divided into multiple clinical subtypes.

signs and symptoms

• Clinical findings in severe generalized RDEB include skin fragility manifest by blistering with minimal trauma that heals with milia and scarring.
• Blistering and erosions affecting the whole body may be present in the neonatal period. Oral involvement may lead to mouth blistering, fusion of the tongue to the floor of the mouth, and progressive diminution of the size of the oral cavity.
• Esophageal erosions can lead to webs and strictures that can cause severe dysphagia. Consequently, malnutrition and vitamin and mineral deficiency may lead to growth restriction in young children.
• Corneal erosions can lead to scarring and loss of vision.
• Blistering of the hands and feet followed by scarring fuses the digits into "mitten" hands and feet, with contractures and pseudosyndactyly.
• The lifetime risk of aggressive squamous cell carcinoma is higher than 90%.
• In contrast, the blistering in the less severe forms of RDEB may be localized to hands, feet, knees, and elbows with or without involvement of flexural areas and the trunk, and without the mutilating scarring seen in severe generalized RDEB.

• In DDEB, blistering is often mild and limited to hands, feet, knees, and elbows, but nonetheless heals with scarring.
• Dystrophic nails, especially toenails, are common and may be the only manifestation of DDEB.

Diagnosis

• The diagnosis of DEB is established in a proband with characteristic clinical findings and the identification of biallelic pathogenic variants (RDEB) or a heterozygous pathogenic variant (DDEB) in COL7A1 by molecular genetic testing.
• The only gene in which pathogenic variants are known to cause DEB is COL7A1.
• If molecular genetic testing is not diagnostic, examination of a skin biopsy with direct immunofluorescence (IF) for specific cutaneous markers and/or electron microscopy (EM) may be necessary for diagnosis.[1].

Treatment

• New blisters should be lanced, drained, and in most cases dressed with a nonadherent material, covered with padding for stability and protection, and secured with an elastic wrap for integrity.
• Infants and children with severe generalized RDEB and poor growth require attention to fluid and electrolyte balance and may require nutritional support, including feeding gastrostomy.
• Anemia is treated with iron supplements and transfusions as needed.
• Other nutritional supplements may include calcium, vitamin D, selenium, carnitine, and zinc.
• Occupational therapy may help prevent hand contractures.
• Surgical release of fingers often needs to be repeated.[2].

NIH genetic and rare disease info

• NIH info on Dystrophic epidermolysis bullosa

Dystrophic epidermolysis bullosa is a rare disease.

Dystrophic epidermolysis bullosa Resources
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Pfendner EG, Lucky AW. Dystrophic Epidermolysis Bullosa. 2006 Aug 21 [Updated 2018 Sep 13]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1304/