What is EB?
All types of EB are characterised by fragility of the skin and mucous membranes that blister and tear from mechanical friction or trauma.
There is yet no cure or treatment for EB, Symptoms can be alleviated by wound care, pain management, and the use of preventive bandages. These are the only treatment options available to this day.
Epidermolysis Bullosa comprises four main types - EB simplex (EBS), junctional EB (JEB), dystrophic EB (DEB), and Kindler EB (KEB), with more than 30 subtypes.
EB Simplex (EBS)
EB Simplex is the most common and mild form of epidermolysis bullosa. It occurs at the epidermis (outer layer of the skin), and mainly affects the palms of the hands and feet, as the proteins that help to hold the layers of skin together are missing in the superficial layer of skin, or what is known as the epidermis.
This type is divided into three subtypes: (localized EBS, moderate EBS, severe EBS)
Approximately 70% of people with the disease have epidermolysis bullosa simplex.
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.
Symptoms & Complications
Blisters mainly on hands and feet
harmless skin spots and colour changes
Itching
skin thickens on the soles of the feet
nails maybe thick and change colour/ shape
blisters can improve during puberty
blistering is widespread
constipation
inside of the mouth is usually affected in infancy stage
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It affects 70% of the epidermis
Junctional EB (JEB)
Epidermolysis Bullosa Junctional is a rare moderate to severe form of epidermolysis bullosa that affects the basement membrane, the structure that keeps the epidermis (outer) and dermis layers together, meaning that the skin tends to rupture easily causing blisters or ulcers in the deeper layers of skin.
EB Junctional comprises two main subtypes: (Intermediate JEB, Severe JEB).
Which genes are affected?
The main JEB subtypes are caused by variants in the LAMA3, LAMB3, and LAMC2 genes containing information needed to make laminin 332. Variants in the COL17A1 gene containing information needed to make type XVII collagen can also result in intermediate and, rarely, in severe JEB phenotypes.
Symptoms & Complications
Harmless skin spots and colour change
Itching
Inside mouth is usually affected
Tooth enamel affected
Eyes are usually affected by blistering
Thinning hair & hair loss
Anaemia (more common in severe JEB)
Skin cancer may occur as complications
Nails loss or thick
Non-healing wounds on buttocks, face, ears, and tips of the fingers and toes
Life expectancy in very limited
Hoarseness and high-pitched wheezing
Inside of the mouth, nose, oesphagus, and windpipe affected.
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It affects 5% of the basement membrane
Dystrophic EB (DEB)
Dystrophic epidermolysis bullosa can be moderate or severe depending on the subtype, as it affects the bottom layer of the skin (Dermis) - the dermis in which the ulcers occur.
Dystrophic EB (DEB) may be inherited as a dominant (DDEB) or recessive (RDEB) trait. Major subtypes of DEB include: (Localized DDEB, Intermediate DDEB, Intermediate RDEB, Severe RDEB).
Which genes are affected?
All subtypes of DEB are caused by variants in the COL7A1 gene containing information needed to make collagen VII.
Symptoms & Complications
Fragile skin mainly affects fingers, toes and nails
sometimes, only nails are affected by colour change and shape
Skin cancer (teen years - most common in severe RDE)
Constipation
Inside of the mouth may be affected
Joints cannot straighten easily
Non- healing wounds
Fusion of the fingers and toes (mainly intermediate RDEB)
Eyes are usually affected by blistering
Oesophageal blistering common
Severe hair loss
Mitten hands
Nails lost completely
Growth delay/ delayed puberty
Weak bones/ spinal fractures
Overcrowding/ malalignment of teeth/ tooth decay
Anaemia
Mouth contracture/ reduced tongue movement
Skin cancer is a frequent cause of death
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It affects 25% of the dermis
Kindler EB (KEB)
KEB is inherited in an autosomal recessive manner; EB Kindler is the rarest type of inherited epidermolysis bullosa.
In Kindler syndrome, blisters can occur in all layers of the skin or internal organs but tend to affect the extremities most severely.
Which genes are affected?
KEB is caused by variants in the FERMT1 gene containing information needed to make the Fermitin family homolog 1 protein.
Symptoms & Complications
Blistering is widespread and tends to affect the extremities.
Loss of ridges and lines of the skin on the hands, such as fingerprints.
Fusion of the fingers and toes leading to "mitten" hands.
Nails maybe thick and change shape/ colour.
Eyes are usually affected by blistering.
Narrowing of the urinary and genital organs can occur.
Blistering tends to decrease with age.
Skin cancer on extremities, lips, or oral cavity (young adulthood).
Skin thickens on the palms of the hands and soles of the feet.
Skin cancer in kindler EB is aggressive and can cause. premature death. Regular check-ups for skin cancer monitoring is required.
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It affects multiple & different levels of the skin layers
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