SNP Shot: Genomic Insights

Epidermolysis bullosa simplex (EBS) is a genetic condition within the epidermolysis bullosa group, causing extremely fragile skin that blisters easily. Even minor friction or injury, such as rubbing or scratching, can trigger blisters and skin erosions. EBS is a primary type of epidermolysis bullosa. The severity of EBS varies greatly. Mild cases involve blistering mainly on the hands and feet, typically healing without scars. However, severe cases can cause widespread blistering, leading to infections, dehydration, and other serious health problems, potentially being life-threatening for infants.

Researchers have identified four major types of EBS.

While the four types of EBS differ in severity, they share overlapping characteristics and are caused by mutations in the same genes. Many researchers now view these forms as a single condition with a range of symptoms.

The localized type (formerly Weber-Cockayne), is the mildest form of EBS. It's characterized by blisters usually limited to the hands and feet, appearing anytime between childhood and adulthood. Thickening and hardening of the skin (hyperkeratosis) can develop on the palms and soles later in life.

The Dowling-Meara type is the most severe form of EBS. Extensive, severe blistering can occur all over the body, including inside the mouth, and blisters may appear in clusters. Blistering is present from birth and often improves with age. Affected individuals also experience abnormal nail growth and hyperkeratosis of the palms and soles.

Another form of EBS, the generalized type (formerly Koebner), involves widespread blisters appearing at birth or in early infancy. The blistering is generally less severe than in the Dowling-Meara type.

EBS with mottled pigmentation is characterized by patches of darker skin on the trunk, arms, and legs that fade in adulthood. This form also features skin blistering from early infancy, hyperkeratosis of the palms and soles, and abnormal nail growth.

Besides the four main types, researchers have identified another skin condition related to EBS called the Ogna type. It is caused by mutations in a different gene than the other types of EBS. It is unclear whether the Ogna type is a subtype of EBS or a separate form of epidermolysis bullosa.

Several other rare variants of EBS have been suggested.

Inheritance:

EBS is usually inherited in an autosomal dominant pattern. This means only one copy of the mutated gene is needed to cause the disorder. Some people inherit the mutation from an affected parent, while others develop it due to a new mutation in the gene with no family history. Rarely, EBS is inherited in an autosomal recessive pattern. In this case, two copies of the mutated gene are needed for the condition to develop. The parents typically each carry one copy of the altered gene but do not have the condition themselves.