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What is Junctional Epidermolysis Bullosa?

What is Junctional Epidermolysis Bullosa?

In a recent scientific paper published on the diagnosis and classification of EB, written by Professor Jo-David Fine, the authors looked at the four major EB types of which Junctional Epidermolysis Bullosa (JEB) is one.

JEB includes all subtypes of EB in which blisters develop within the mid portion or junction between the top and lower layers (epidermis and dermis) of the skin. This is the skin basement membrane zone.

There are number of genetic mistakes that are included in JEB – and these mean that there are a number of possible proteins or building blocks that are missing that leave the skin fragile and likely to blister. The missing proteins may be laminin 332, collagen XVII, α6ß4 integrin or α3 integrin subunit. The genetic mistakes are inherited by what is called autosomal recessive which means that genes are required from both parents for the symptoms to be apparent, it also means that people can “carry” the genetic mistake and not show any symptoms.

To give you an idea of what those proteins do; Collagen is important because it is one of the main structural component in the skin; Laminins are important for the maintenance of healthy tissues; Integrins are receptors on cells that help the cells in the skin talk to each other so mistakes when any of these proteins are made can cause problems.

The term JEB non-Herlitz can be split into JEB generalised intermediate or localised and people living with this type of EB can exhibit a range of symptoms all over the body or in localised areas, and the severity can vary.

This is an extract from a table from the paper by Fine which shows the possible variability (the scale of the numbers goes from Absent/1+/2+/3+/4+/Excessive showing the increasing severity):

Blisters

3+ 4+

Milia (skin deposits)

1+ 2+

Atrophic scarring (indented scars)

2+ 3+

Dystrophic or absent nails

2+ to 4+

Anaemia

Absent to 2+

Growth retardation

Absent to 2+

Mouth soft tissue abnormalities

1+ to 3+

Tooth enamel hypoplasia (thin)

4+

Dental caries or tooth decay

Excessive

Problems with gastrointestinal tract (digestion), genitourinary tract (reproductive and urinary areas), ocular (eyes), respiratory tract (breathing)

Absent to 2+

Risk of squamous cell carcinoma by age 30

2+ 

Read more about JEB and the other types of EB.

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