EB Simplex

Types of EB
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Epidermolysis Bullosa Simplex (EBS)

Epidermolysis Bullosa Simplex is the most common type of EB, accounting for around 70% of cases. It is usually dominantly inherited and involves disorders of the genes for Keratin 5 and 14, and Plectin.

EBS may be localised to the hands and feet or there may be a generalised distribution with relatively mild internal involvement.

Those with EBS may have thickened calluses on palms and soles, oral blistering during infancy and rough, thickened fingernails and toenails. EBS does not usually scar. There are rare recessive forms. EBS with plectin mutations may be associated with muscular dystrophy.

Researchers have identified 4 main sub-types of EBS:

  • Localised EBS (formerly Weber-Cockayne type),
  • EBS intermediate (formerly EBS generalised or Koebner type)
  • EBS severe (formerly EBS generalised severe or Dowling-Meara EBS), and
  • EBS with mottled pigmentation

Localised EBS

This is the most common type of EBS and the least severe. Skin blistering is usually limited to hands and feet and is often diagnosed in early childhood as the child becomes more mobile. Hyperkeratosis (thickening and hardening of the skin), particularly on the palms of hands and soles of feet, may occur due to rubbing.

EBS intermediate

EBS intermediate is characterised by widespread blistering that is present from birth. It is generally more severe than localised EBS but less severe than EBS severe.

EBS severe

This is the most severe form of EBS. Blistering is present from birth and can be anywhere on the body (including inside the mouth). There severity of this subtype varies widely, with blistering tending to improve with age, although hyperkeratosis becomes more common with increasing age. In very severe cases, EBS Severe is fatal in early infancy.

EBS with mottled pigmentation

This is a rare form of EBS caused by a mutation in the KRT5 gene. It is usually identified at birth due to the fragility of the skin, with blistering occurring in response to minor friction. Skin appears mottled with areas of lighter and darker skin (hypo- and hyper-pigmentation).