General description
Junctional Epidermolysis Bullosa is the third most common form of EB, representing 5% of cases.
The pathology is present at birth or appears during the neonatal period. It is inherited from both parents who each have a recessive gene. The child has a 25% chance of contracting the disease, and a 50% chance that it is a healthy carrier (recessive autosomal transmission).
JEB variants are characterised by the separation of the skin at the level of the lamina lucida of the dermo-epidermal junction. It is characterised by the fragility of the skin and mucous membrane. It manifests itself in the form of phlyctens that appear of their own accord or following a minor trauma (rubbing).
The areas of skin separation are often large, ulcerated and can form on the skin around the oral and nasal cavities, on the fingers and toes and on the internal mucous membrane, notably the trachea.
The phlyctens generally heal without scarring.
JJEB affects less than 1 person in 1,000,000 in the USA.
EB is classified into two groups:
- Herlitz JEB
- Non-Herlitz JEB
The two types are different in terms of severity, but their characteristics overlap considerably as they can be caused by mutation of the same genes.
Sub-types of DEB
Non-Herlitz JEB
Non-Herlitz JEB includes the least severe forms of JEB.
The blistering associated with non-Herlitz JEB may be limited to the hands, feet, knees, and elbows, and it often improves after the newborn period. Other characteristic features of this condition 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.
Herlitz JEB
Junctional Epidermolysis Bullosa Herlitz is the most severe form of all types of EB. From birth or beginning in early childhood, the individual affected presents with phlyctens across vast regions of the body. The separation of the skin also applies to the mucous membrane, such as the interior of the mouth, as well as the digestive tract, which complicates oral alimentation or even makes it impossible. As a result, many children affected are malnourished and display very slow growth. The persistence of extensive wounds leads to secondary infections.
The healing process of the phlyctens leads to the formation of large red blisters called granulation tissue. This tissue bleeds easily and freely, which makes children vulnerable to serious infection and denutrition. Furthermore, an accumulation of scarring granulomes in the respiratory tract can cause complications with breathing and may require a tracheotomy.
Other complications may lead to the fusion of the fingers and toes, which deforms the joints and can severely restricts movement.
As the symptoms of JEB Herlitz are very invasive, babies born with this pathology do not usually survive for more than a year.
Transmission : How do people inherit Junctional Epidermolysis Bullosa ?