Genetics.....[JEB]

Junctional Epidermolysis Bullosa [JEB].....

Junctional epidermolysis bullosa (JEB) is one of the major forms of Epidermolysis Bullosa.

Junctional Epidermolysis Bullosa [JEB] can be classified into 2 main types: ‘Herlitz JEB’ and ‘non-Herlitz JEB’. Although the types differ in severity but their features overlap significantly—which is caused by mutations in the same genes.

Herlitz JEB is the more severe form of JEB. From birth or early infancy the baby has 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 makes eating and swallowing difficult which in turn creates problems in digestion. As a result many affected children have chronic malnutrition and slow growth. 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 build-up of granulation tissue in the airway can lead to a weak, hoarse cry and difficulty breathing. Other complications of Herlitz JEB may include fusion of the fingers and toes, abnormalities of the fingernails and toenails, joint deformities (contractures) that restrict movement and hair loss (alopecia). Because the signs and symptoms of Herlitz JEB are so severe, infants with this condition usually do not survive beyond the first year of life.

Exuberant granulation tissue arising on the nape of the neck of a child with Herlitz JEB.

Fine Orphanet Journal of Rare Diseases 2010 5:12 

The milder form of JEB is called non-Herlitz JEB. The blistering associated with non-Herlitz JEB usually limited to the hands, feet, knees and elbows which often improves after the newborn period. Other characteristic features of non-Herlitz JEB include alopecia, malformed 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. Non-Herlitz JEB is typically associated with a normal lifespan.