From OMIMIntermediate junctional epidermolysis bullosa 1A (JEB1A) is an autosomal recessive blistering disease of skin and mucous membranes. Generalized trauma-induced blistering occurs from birth. Blistering is less severe than in severe JEB (see 226700), usually without the tendency for developing chronic granulation tissue. The plane of skin cleavage is through the lamina lucida of the cutaneous basement membrane zone. Nail dystrophy or loss and dental enamel defects are present. Scarring or nonscarring alopecia and diffuse hair loss may occur (summary by Has et al., 2020). Blistering does not affect the life span of affected individuals (Pulkkinen and Uitto, 1998; Sybert, 2010).
Genetic Heterogeneity of Junctional Epidermolysis Bullosa
Another form of JEB that is caused by mutation in the LAMB3 gene is severe JEB1B (226700).
Forms of JEB caused by mutation in the LAMA3 gene (600805) are intermediate JEB2A (619783), severe JEB2B (619784), and laryngoonychocutaneous JEB2C (245660).
Forms of JEB caused by mutation in the LAMC2 gene (150292) are intermediate JEB3A (619785) and severe JEB3B (619786).
Intermediate JEB4 (619787) is caused by mutation in the COL17A1 gene (113811).
Forms of JEB caused by mutation in the ITGB4 gene (147557) are intermediate JEB5A (619816) and JEB with pyloric atresia (JEB5B; 226730).
Another form of JEB that includes pyloric atresia (JEB6; 619817) is caused by mutation in the ITGA6 gene (147556).
JEB with interstitial lung disease and nephrotic syndrome (JEB7; 614748), also known as interstitial lung disease, nephrotic syndrome, and epidermolysis bullosa (ILNEB), is caused by mutation in the ITGA3 gene (605025).
Reviews
Pulkkinen and Uitto (1999) reviewed the pathophysiology and phenotypic and genetic heterogeneity of epidermolysis bullosa.
http://www.omim.org/entry/226650 From MedlinePlus GeneticsJunctional epidermolysis bullosa (JEB) is a major form of epidermolysis bullosa, a group of genetic conditions that cause the skin to be very fragile and to blister easily. Blisters and areas of skin loss (erosions) form in response to minor injury or friction, such as rubbing or scratching. Researchers classify junctional epidermolysis bullosa into two main types: JEB generalized severe (formerly known as Herlitz JEB) and JEB generalized intermediate (formerly known as non-Herlitz JEB). Although the types differ in severity, their features overlap significantly, and they can be caused by mutations in the same genes.
Other complications of JEB generalized severe can include fusion of the fingers and toes, abnormalities of the fingernails and toenails, joint deformities (contractures) that limit movement, hair loss (alopecia), and thinning of the protective outer layer (enamel) of the teeth. Because the signs and symptoms of JEB generalized severe are so serious, infants with this condition usually do not survive beyond the first year of life.
JEB generalized severe is the more serious form of the condition. From birth or early infancy, affected individuals have blistering over large regions of the body. Blistering also affects the mucous membranes, such as the moist lining of the mouth and digestive tract, which can make it difficult to eat and digest food. As a result, many affected children are undernourished and grow slowly. The extensive blistering leads to scarring and the formation of red, bumpy patches called granulation tissue. Granulation tissue bleeds easily and profusely, making affected infants susceptible to serious infections and loss of necessary proteins, minerals, and fluids. Additionally, a buildup of granulation tissue in the airway can lead to a weak, hoarse cry and difficulty breathing.
The milder form of junctional epidermolysis bullosa is called JEB generalized intermediate. The blistering associated with JEB generalized intermediate may be limited to the hands, feet, knees, and elbows, and it often improves after the newborn period. Other characteristic features of this form of the condition include hair loss, abnormal fingernails and toenails, and irregular tooth enamel. Most affected individuals do not have extensive scarring or granulation tissue formation, so breathing difficulties and other severe complications are rare. JEB generalized intermediate is typically associated with a normal lifespan.
https://medlineplus.gov/genetics/condition/junctional-epidermolysis-bullosa