Non-Herlitz JEB (JEB-nH) generally is less severe than Herlitz JEB, and there are two main types:
- generalized non-Herlitz JEB, which may be caused by mutations in the collagen XVII gene or the laminin-332 gene
- localized non-Herlitz JEB, which is caused by mutations in the collagen type XVII gene
Generalized non-Herlitz JEB presents at birth with widespread blistering and erosions. Blistering usually is worse in periods of warm, humid weather. Milia, scarring and nail dystrophy are common, and mild keratoderma of the palms and soles may occur. Blistering on the scalp is common, and permanent hair loss (alopecia) may occur. Granulation tissue is rare. Poor dental enamel, oral erosions and dental caries are common, often necessitating extensive dental reconstruction. Poor growth, anemia, and blistering and other problems involving the trachea/respiratory tract, intestines/gastrointestinal tract, eyes or genitourinary tract may occur, but with less frequency and, often, with less severity than is seen with Herlitz JEB. Laryngeal blisters and resultant scars cause a hoarse cry during infancy, and a hoarse, husky voice may remain through adulthood. Tracheal blisters may occur in individuals with JEB-nH, and, if they occur when the affected person is an infant with a relatively small trachea, they may cause occlusion of the trachea and suffocation if not recognized and treated.
Osteopenia/osteoporosis has been reported in patients with JEB, and may be a result of malnutrition and malabsorption problems as well as a decrease in mobility and weight-bearing activities. Pseudosyndactyly does not occur. The development of squamous cell carcinoma of the skin is possible; individuals with JEB should be evaluated annually by a dermatologist. Other types of skin cancer do not occur in association with non-Herlitz JEB.
Localized non-Herlitz JEB presents at birth with fewer, more localized blisters and erosions. Milia, scarring and nail dystrophy are common. Granulation tissue is not seen. Poor dental enamel, oral erosions and dental caries may be seen. Poor growth, anemia, and blistering and other problems involving the trachea/respiratory tract, intestines/gastrointestinal tract, eyes or genitourinary tract are not seen. Pseudosyndactyly does not occur. The development of skin cancer is no more likely associated with non-Herlitz JEB.