EB simplex (EBS) is the most common EB type comprising three main subtypes:
Localized EBS (previously known as Weber-Cockayne)
Intermediate EBS (previously known as EBS generalized intermediate, EBS Köbner)
Severe EBS (previously known as EBS generalized severe, EBS Dowling-Meara)
What are the common clinical symptoms of these EBS subtypes?
Blistering happens in the upper layer of the skin causing erosions and crusts. Blisters can heal with hyperpigmentation (darkening of the skin). Blistering is made worse by heat, humidity, and sweating. Blistering tends to decrease during adolescence when it may only appear on the hands and feet. Milia (small, hard, pale nodules) may appear in the first weeks of life and EB naevi (birthmarks or moles) are common. Plantar keratoderma (the thickening of the skin on the soles of the feet) develops gradually, which can be painful and reduce mobility. Nails may be thick and dystrophic (appear damaged, misshapen, discoloured, and curvy), particularly in EBS severe. Hair is not affected.
Which genes are affected?
The main EBS subtypes are caused by variants in the KRT5 and KRT14 genes containing information needed to make proteins keratin 5 and keratin 14.
How is it inherited?
In most cases, EBS is inherited in an autosomal dominant manner (de novo inheritance is also possible). Although autosomal recessive inheritance is possible, it is rarer.
Rare subtypes of EBS
There are a number of rare subtypes of EBS. Click on the button below to find out more about the symptoms and affected genes of each.
Blistering starts at birth or in early infancy and mainly appears on the hands and feet.
Blistering starts at birth and is generalised but less severe.
Ulcerated areas on the hands, feet, and nails, as well as blistering, are common at birth and the skin is noticeably fragile. Large tense blisters can appear after minimal trauma or spontaneously in the neonatal period. In infants, the oral mucosa (the mucous membrane lining the inside of the mouth) is also usually affected, reflux can occur, and stunted growth is common. Confluent palmoplantar keratoderma (widespread thickening of the skin on the palms of the hands and soles of the feet) is mostly seen in severe EBS. Neonatal complications associated with severe EBS can be life threatening in the first year of life.
The information above has been sourced from the ‘Consensus reclassification of inherited epidermolysis bullosa and other disorders with skin fragility’ article published in the British Journal of Dermatology https://doi.org/10.1111/bjd.18921