Junctional Epidermolysis Bullosa (JEB)
Junctional epidermolysis bullosa is recessively inherited and involves mutations in the genes for several components of the junction within the basement membrane zone (lamina lucida) between the epidermis (upper layer of skin) and dermis (lower layer of skin). It is a rare form and accounts for 5% of total EB cases.
JEB most commonly results from mutations in the Lama3, Lam3, Lamc2 and Col17A1 genes. Lam3 are the most common causing about 70% of all cases of junctional EB.
Researchers classify JEB into two main types – JEB generalised severe (formerly known as Herlitz junctional) and JEB intermediate (formerly known as Non Herlitz junctional).
JEB generalised severe
This JEB subtype is due to mutations in any of the laminin 332 chains and can be very severe. Death often occurs in infancy due to overwhelming infection (sepsis), malnutrition, dehydration, electrolyte imbalance, pyloric atresia (obstruction of the lower part of the stomach), or obstructive airway complications.
This is the less severe form of JEB where blistering may be confined to hands and feet, knees and elbows. Other features include hair loss, abnormal fingernails and toenails and irregular teeth enamel. Typically this form of EB can be associated with a normal life span.