Junctional epidermolysis bullosa (JEB) is characterized by fragility of the skin and mucous membranes, manifest by blistering with little or no trauma. Blistering may be severe and granulation tissue can form on the skin around the oral and nasal cavities, fingers and toes, and internally around the upper airway. Blisters generally heal with no significant scarring. Broad classification of JEB includes JEB generalized severe and JEB generalized intermediate. In JEB generalized severe, blisters are present at birth or become apparent in the neonatal period. Congenital malformations of the urinary tract and bladder may also occur. In JEB generalized intermediate, the phenotype may be mild with blistering localized to hands, feet, knees, and elbows with or without renal or ureteral involvement. Some individuals never blister after the newborn period. Additional features shared by JEB and the other major forms of epidermolysis bullosa (EB) include congenital localized absence of skin (aplasia cutis congenita), milia, nail dystrophy, scarring alopecia, hypotrichosis, pseudosyndactyly, and other contractures.

Epidermolysis bullosa with pyloric atresia (EB-PA) is characterized by fragility of the skin and mucous membranes, manifested by blistering with little or no trauma; congenital pyloric atresia; and ureteral and renal anomalies (dysplastic/multicystic kidney, hydronephrosis/hydroureter, ureterocele, duplicated renal collecting system, absent bladder). The course of EB-PA is usually severe and often lethal in the neonatal period. Most affected children succumb as neonates; those who survive may have severe blistering with formation of granulation tissue on the skin around the mouth, nose, fingers, and toes, and internally around the trachea. However, some affected individuals have little or no blistering later in life. Additional features shared by EB-PA and the other major forms of EB include congenital localized absence of skin (aplasia cutis congenita) affecting the extremities and/or head, milia, nail dystrophy, scarring alopecia, hypotrichosis, contractures, and dilated cardiomyopathy.

Severe junctional epidermolysis bullosa 2B (JEB2B) is an autosomal recessive skin blistering disorder characterized by extreme fragility of the skin and epithelia of various extracutaneous tissues. Skin blisters and erosions are present at birth. The plane of skin cleavage is through the lamina lucida of the cutaneous basement membrane zone. Oral mucosal blistering and laryngeal and esophageal mucosal involvement can occur. Patients usually die before 1 year of age (summary by Has et al., 2020). For a discussion of genetic heterogeneity of the subtypes of JEB, see JEB1A (226650). Reviews Has et al. (2020) reviewed the clinical and genetic aspects, genotype-phenotype correlations, disease-modifying factors, and natural history of epidermolysis bullosa.

Intermediate junctional epidermolysis bullosa 3A (JEB3A) is an autosomal recessive blistering disease of skin and mucous membranes. Blistering is less severe than in severe JEB (see 226700). The plane of skin cleavage is through the lamina lucida of the cutaneous basement membrane zone. Nail and dental abnormalities occur. Blistering does not affect the life span of affected individuals (summary by Has et al., 2020). For a discussion of genetic heterogeneity of the subtypes of JEB, see JEB1A (226650). Reviews Has et al. (2020) reviewed the clinical and genetic aspects, genotype-phenotype correlations, disease-modifying factors, and natural history of epidermolysis bullosa.

Severe junctional epidermolysis bullosa 3B (JEB3B) is an autosomal recessive skin blistering disorder characterized by extreme fragility of the skin and epithelia of various extracutaneous tissues. Skin blisters and erosions are present at birth. The plane of skin cleavage is through the lamina lucida of the cutaneous basement membrane zone. Patients die in infancy to early adulthood (summary by Has et al., 2020). For a discussion of genetic heterogeneity of the subtypes of JEB, see JEB1A (226650). Reviews Has et al. (2020) reviewed the clinical and genetic aspects, genotype-phenotype correlations, disease-modifying factors, and natural history of epidermolysis bullosa.

Intermediate junctional epidermolysis bullosa 5A (JEB5A) is an autosomal recessive blistering disease of skin and mucous membranes. Blistering is less severe than in severe JEB (see 226700). The plane of skin cleavage is through the lamina lucida of the cutaneous basement membrane zone. Nails may be dystrophic and dental enamel defects are present. Blistering does not affect the life span of affected individuals (summary by Has et al., 2020). For a discussion of genetic heterogeneity of the subtypes of JEB, see JEB1A (226650). Reviews Has et al. (2020) reviewed the clinical and genetic aspects, genotype-phenotype correlations, disease-modifying factors, and natural history of epidermolysis bullosa.

Epidermolysis bullosa with pyloric atresia (EB-PA) is characterized by fragility of the skin and mucous membranes, manifested by blistering with little or no trauma; congenital pyloric atresia; and ureteral and renal anomalies (dysplastic/multicystic kidney, hydronephrosis/hydroureter, ureterocele, duplicated renal collecting system, absent bladder). The course of EB-PA is usually severe and often lethal in the neonatal period. Most affected children succumb as neonates; those who survive may have severe blistering with formation of granulation tissue on the skin around the mouth, nose, fingers, and toes, and internally around the trachea. However, some affected individuals have little or no blistering later in life. Additional features shared by EB-PA and the other major forms of EB include congenital localized absence of skin (aplasia cutis congenita) affecting the extremities and/or head, milia, nail dystrophy, scarring alopecia, hypotrichosis, contractures, and dilated cardiomyopathy.