Clinical characteristics: Dystrophic epidermolysis bullosa (DEB) is a genetic skin disorder affecting skin and nails that usually presents at birth. 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. Absence of a known family history of DEB does not preclude the diagnosis.
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/testing: 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.
Management: Treatment of manifestations: 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.
Prevention of primary manifestations: If a fetus is known to be affected with any form of DEB, cesarean delivery may reduce trauma to the skin during delivery; age-appropriate play involving activities that cause minimal trauma to the skin is encouraged; dressings and padding are needed to protect bony prominences from blister-inducing impact.
Surveillance: Beginning in the second decade of life, biopsies of abnormal-appearing wounds that do not heal or have exuberant scar tissue are indicated for evidence of squamous cell carcinoma. Suggested regular testing includes screening for anemia and deficiencies of iron, zinc, vitamin D, selenium, and carnitine every 6-12 months. Yearly echocardiograms to identify dilated cardiomyopathy and bone mineral density studies to identify osteoporosis are recommended.
Agents/circumstances to avoid: Poorly fitting or coarse-textured clothing and footwear; activities/bandages that traumatize the skin.
Evaluation of relatives at risk: Evaluating an at-risk newborn for evidence of blistering is appropriate so that trauma to the skin can be avoided as much as possible.
Genetic counseling: Dystrophic epidermolysis bullosa is inherited in either an autosomal dominant (DDEB) or autosomal recessive (RDEB) manner. Molecular characterization of pathogenic variants is the only accurate method to determine mode of inheritance and recurrence risk; phenotype severity and IF/EM findings alone are not sufficient.
DDEB. About 70% of individuals diagnosed with DDEB are reported to have an affected parent. If a parent of a proband with DDEB is affected, the risk to the sibs is 50%. Each child of an individual with DDEB has a 50% chance of inheriting the pathogenic variant.
RDEB. Each sib of an affected individual whose parents are both carriers has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
Once the COL7A1 pathogenic variant(s) have been identified in an affected family member, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing are possible.
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