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Recessive dystrophic epidermolysis bullosa, generalized intermediate
Recessive dystrophic epidermolysis bullosa (RDEB)-generalized other, also known as RDEB non-Hallopeau-Siemens type, is a subtype of DEB (see this term) characterized by generalized cutaneous and mucosal blistering that is not associated with severe deformities.
ORPHA:89842Classification level: Disorder
- Autosomal recessive dystrophic epidermolysis bullosa generalisata mitis
- Autosomal recessive dystrophic epidermolysis bullosa, generalized other
- Generalized mitis RDEB
- RDEB generalisata mitis
- RDEB, generalized intermediate
- RDEB, non-Hallopeau-Siemens type
- RDEB-generalized other
- Recessive dystrophic epidermolysis bullosa, non-Hallopeau-Siemens type
- Recessive dystrophic epidermolysis bullosa-generalized other
- Prevalence: Unknown
- Inheritance: Autosomal recessive
- Age of onset: Neonatal
- ICD-10: Q81.2
- OMIM: -
- UMLS: -
- MeSH: -
- GARD: 12794
- MedDRA: -
Its exact prevalence is unknown but this sub-type represents the second most common RDEB, the first one being severe generalized RDEB (RDEB- sev gen; see this term). The prevalence of all RDEB sub-types, with the exclusion of RDEB-sev gen, has been estimated at 1/2,040,816 in the United States.
Under the term RDEB-other are grouped a spectrum of phenotypes, showing highly variable severity of the cutaneous and mucosal involvement. The disease manifests at birth or during the neonatal period with generalized blistering. Aplasia cutis congenita (congenital absence of the skin) can also be observed at birth. Healing of blisters results in the development of milia, atrophic scarring (less severe than in RDEB- sev gen), dystrophic nails, and, occasionally, albopapuloid lesions (ivory-white colored scar-like papules) and scalp abnormalities. In some patients, the scarring phenomena can lead to a certain degree of pseudosyndactyly and loss of nail plates. Extracutaneous involvement is similar but less severe than in severe generalized RDEB with no hand/foot deformities associated with this disease. Oral cavity lesions and excessive dental caries are common. Patients have a lower risk of esophageal strictures and corneal injury than RDEB-sev gen. Growth delay and anemia are uncommon. Genitourinary tract involvement is rare. Patients have an increased risk of developing squamous cell carcinomas (35.8% by age 50 according to the U.S. EB national registry).
The disease is caused by mutations within the type VII collagen gene (COL7A1) that lead to an alteration of function or a reduction in the amounts of collagen VII. This impairs collagen VII assembly into anchoring fibrils which anchor the basement membrane to the underlying dermis. This in turn causes reduced skin resistance to minor trauma.
Diagnosis is suspected at clinical examination and is confirmed by immunofluorescence antigen mapping and/or transmission electron microscopy on skin samples showing a cleavage plane located below the lamina densa of the cutaneous basement membrane zone. Genetic testing confirms the diagnosis.
The differential diagnosis includes other forms of EB. In the neonatal period, aplasia cutis congenita, herpes simplex infection, congenital erosive and vesicular dermatosis, epidermolytic ichthyosis, linear IgA bullous dermatosis, bullous pemphigoid, neonatal pemphigus and pemphigoid gestationis, bullous impetigo, and staphylococcal scalded skin syndrome (see these terms) may need to be considered.
DNA-based prenatal diagnosis is possible for at risk pregnancies.
Transmission is autosomal recessive.
Management and treatment
Management is preventive: protective padding of the skin reduces blistering and careful wound care prevents secondary infection and reduces scarring. Oral hygiene is important for management of caries. Nutritional requirements should be evaluated by a dietitian. Esophageal strictures are treated by balloon dilatation with fluoroscopic guidance. A regular follow-up is necessary for the surveillance of SCC. The treatment of SCC is surgical and involves full-thickness excision with wide margins.
In most cases, life expectancy is normal. However, there is an increased risk of development of metastasizing squamous cell carcinomas with a cumulative risk of mortality of 21.5% by age 55 according to the U.S. EB national registry.
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