Through research it is now known that mutations in the genes encoding alpha 6, beta 4 integrin, collagen XVII or one of the three chains of Laminin 5 contribute to defects in the formation of hemidesmosomes or anchoring filaments.
Defects within any of those components of the skin allows for the separation of tissue and blister formation whenever there is friction or trauma to an area. In many instances blistering can occur spontaneously.
There are three major sub-types of Junctional EB. Herlitz, non-Herlitz and Junctional EB with associated Pyloric Atresia. Though Junctional EB is considered a non-scarring form of EB, tightening and thinning of the skin does occur. In many instances residual atrophic scarring occurs.
JEB is an autosomal recessive condition. This means both parents are healthy carriers. Healthy carriers are non-symptomatic and will never develop the illness. When each parent has a copy of the altered gene, there is a 25% or 1 in 4 chance the child will be affected by Junctional EB. Unfortunately, there is no test to detect carriers for JEB. We are made aware that the parents are carriers after the child is born.
Junctional Herlitz EB is a very severe form of EB. These infants often die during infancy due to overwhelming infection (sepsis), malnutrition, dehydration, electrolyte imbalance or complications resulting from blistering in the respiratory, gastrointestinal or genitourinary tract.
Some babies develop a hoarse cry and breathing difficulties which indicates internal involvement as well. These infants often fail to gain weight. These are usually symptoms of the severe form of Junctional EB.
Blistering is usually present at birth, however, there have been instances of infants being discharged to home, with a small blister on the finger or lip. After they are home, the blistering becomes more apparent warranting a visit to the physician. Skin blistering and ulcerations can occur spontaneously on the arms, hands, finger tips, back of the head, neck, shoulders, trunk, buttocks, legs and feet and toes (generalized distribution). Nails may be ulcerated or dystrophic. Warmer climates can exacerbate blistering. Blistering is noted on perioral (around the mouth) and mucosal surfaces as well. Oral lesions may affect eating causing weight loss.
Electron microscopic evaluation of the structure of the skin in a patient affected with JEB-H usually shows skin separation in the lamina lucida within the basement membrane zone. Absent or reduced amounts of hemidesmosomes may also be apparent.
Junctional Herlitz EB mutations are present on the genes encoding one of the three chains of Laminin 5.
Generalized blistering and mucosal involvement may be evident at birth or soon after. Blistering may be mild to severe. Erosions on finger and toenails, nail dystrophy or absence of nails may be evident. Erosions and loss of hair (alopecia) upon the scalp may occur. Granulation tissue around mouth and nares may be seen. There may be some scarring and thinning of the skin on affected areas (atrophic scarring). Warmer climates can exacerbate blistering. Though laryngeal involvement (hoarse cry) may be experienced in early infancy, respiratory distress is a rare occurrence in this type of Junctional EB.
The infant may suffer complications such as infection, dehydration, electrolyte imbalances, respiratory, gastrointestinal, and/or genitourinary tract involvement. These complications may lead to death.
Electron microscopic evaluation of the structure of skin in a patient affected with JEB-nH shows skin separation at the level of the lamina lucida of the basement membrane zone. Variable appearance of hemidesmosomes may be visualized as well.
JEB-nH mutations usually involve the genes encoding type XVII collagen also called (BP 180 ). Occasionally mutations in laminin 5 are seen.
We are not sure if Tripp has Herlitz or non-Herlitz. The biopsies were inconclusive.
Read more about EB at www.debra.org