EB disease – types, symptoms, treatment, inheritance

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The mysterious-sounding EB disease is “vesicular separation of the epidermis”, which affects about 500 people in Poland. It is a group of genetic diseases for which modern medicine has still not found a cure. The most severe type of EB is primarily a source of indescribable pain.

EB – what is this disease?

EB (epidermolysis bullosa) is a group of skin diseases that affect 1 in 50 people. people worldwide. It is assumed that 500 people suffer from them in Poland. The word “suffers” is not accidental, because the skin of patients is so sensitive that even the slightest pressure causes the appearance of extremely painful blisters.

EB is a genetic disease. It occurs when, when rewriting the genetic code, certain genes are damaged – different for different types of the disease. The common denominator for all types is the appearance of blisters in one of the three layers of the skin – the epidermis (EBS), the basement membrane (EBJ), or the dermis (EBD).

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EB – symptoms

The symptoms of EB are visible to the naked eye. As a result of mechanical injuries, pressure, burns, and sometimes even the squeezing of clothing, blisters appear on the skin, which then burst and stratify the epidermis. In addition, there are milia, pigmentation discoloration, epidermal defects, scars and erosions.

In some patients the skin lesions are small, in others they appear all over the body. The occurrence of scarring between the fingers and toes leads to contractures and, consequently, adhesions. It happens that this type of eruption also occurs on the epithelium of organs and mucous membranes. EB disease makes it difficult to eat, and everyday activities such as walking or grasping objects become almost impossible.

In addition, these erosions, blisters, scars and adhesions may cause strictures, which in turn may also affect internal organs, such as the gastrointestinal tract (adhesions of the esophagus and rectum), urinary tract or lungs. EB disease is also associated with defects in tooth enamel and inflammation of the eyelid margins. It should be emphasized here that the course of the disease, i.e. its type and severity of symptoms, depends on the genetic mutation.

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EB – diagnostics

Initial diagnosis is made on the basis of symptoms. Genetic tests and microscopic examination of the skin section can give an answer to which type of disease we are dealing with.

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Treatment of EB disease

The answer to the question of whether EB is curable is, unfortunately, negative. Vesicular separation of the epidermis is not only very painful, but also impossible to heal. So far, no effective cure has been found. The prognosis for EB is therefore pessimistic.

On the other hand, there are experimental programs carried out abroad, involving bone marrow transplantation in patients with vesicular separation of the epidermis. Unfortunately, the treatment of EB in the USA costs about PLN 6 million and requires qualification.

In disease, it is possible to relieve pain by using special dressings that should be changed at least 3 times a day. In the case of EB disease, ordinary gauze or patches must not be used, because they cause the epidermis to peel off. Special dressings are intended for this purpose with medical plasters, and for their removal dedicated agents. All of them are fully reimbursed by the state and available in hospitals.

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EB – types

EB disease has many different varieties. Some symptoms may be mild, while others may be fatal. Among the varieties of this disease, five basic forms can be mentioned.

EB – regular character

Common form (epidermolysis bullosa simplex) – is an autosomal dominant type. In other words, this type of sick EB is caused by just one copy of an abnormal, or mutated, gene. This means that when you give birth to this type of disease, you pass on to your child only one copy of the mutated gene, the child who received it will also struggle with the disease and its symptoms.

It should be mentioned that the common form is the most common type of EB disease, and its symptoms, i.e. bladder and erosions visible on the skin, in most cases appear in the first years of life. Most often, all changes affect exposed parts of the body, which are very susceptible to mechanical injuries (hands, knees, elbows). In the case of this character, three varieties are distinguished:

1. Weber-Cockayne character – autosomal dominant type. In this case, the genes encoding keratin proteins are mutated. Blistering skin lesions appear on the feet and sometimes also on the hands. They can manifest themselves after longer walks in older children and adolescents. Blisters in the skin are caused by the separation of individual layers of the epidermis from each other.
2. The character of Dowling-Meary – a form characterized by severe course and electron microscopy image (cytoplasmic “tufts” of tonofilaments). Blisters form everywhere, but mostly on the feet and soles, around the mouth, and around the nape and neck. Sometimes scarring can form due to inflammatory processes, but this is not always the case. The disease worsens with age.
3. Koebner character – the disease, like the first form on the list, is caused by mutations in the keratin genes. The lesions are hyperkeratotic, blistering, sometimes the blisters are hemorrhagic, and the clinical picture shows erosions. This character appears already in infancy. Sometimes, as in the previous form, pigmentation disorders (hypo- or hyperpigmentation) occur.

EB – hemidesmosomal form

Hemidesmosomal form – is inherited in an autosomal dominant or recessive manner. On the skin of a sick child, blisters appear at birth.

EB – form of junctionalis EB

The junctionalis form EB – it is a borderline form of EB and the disease is caused by mutations in the gene encoding laminin and integrins.

This form has two varieties, the first EB Herlitz, a very rare and at the same time fatal variety, which is characterized by the fact that the sick child is born with extensive epidermal defects. In addition, in this variant of EB, the disease does not affect the hands and feet so much, and there is no scarring, syndactyly and no milia. Despite the use of drugs, death occurs in infancy.

The second type is EB with pyloric atresia, which is accompanied by the title pyloric atresia (sometimes atresia of the esophagus or duodenum), i.e. the lack of light of a given organ. In this variant, the prognosis is also poor, with death occurring shortly after birth. The resulting blisters are formed as a result of a defect in the basal membrane, i.e. the membrane that separates the epidermis from the dermis.

EB – dystrophic form

Dystrophic form (EB dystrophica) – in this case, a mutation of the gene encoding collagen is responsible for the development of the disease. It should be mentioned that it has two forms (depending on the method of inheritance), i.e. dominant inheritance i recessive. The first character is much rarer than the second.

Characteristic in this case is the formation of scars and milia on the skin after ruptured blisters. Importantly, this variety may become milder with age. As for the recessive form, its formation requires two copies of the mutated gene (people with one copy are carriers of the disease). This form is much more severe, and blisters appear on the skin in the first months of life. In addition, due to scarring, there is also distortion of the hands, atrophy of nails and alopecia of the scalp.

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EB – causes

As for the causes of EB disease, they are caused by mutations in the genes encoding various proteins, which in turn are involved in the formation of connections between the dermis, the basement membrane and the epidermis, and between epidermal cells. We can distinguish several types of the disease depending on the gene in which the mutation took place:

1. EBS (epidermolysis bullosa simplex) – this type of disease is caused by a mutation in one of the genes: KRT5, KRT14, PLEC1, ITGA6, ITGB4, PKP1, DSP1. For example, the KRT 5 gene encodes keratin 5, a protein that forms the epidermis. The subtype of the disease with this mutation is called Epidermolysis Bullosa Webera-Cockayne’a.
2. EBJ (epidermolysis bullosa junctionalis) – this type of disease is caused by a mutation in one of the genes: LAMB3, LAMC2, LAMA3 (these are the genes encoding laminin – a protein that is the main component of the basal membrane), as well as COL17A1, ITGA6, ITGB4.
3. EBD (epidermolysis bullosa dystrophica) – this type of disease is in turn caused by a mutation in the COL7A gene, which contains the necessary information on the formation of type VII collagen. This type of protein is found in epithelial tissue, incl. in the skin and on the surface of arteries. This subtype of the disease is called Epidermolysis bullosa Hallopeau-Siemensa.

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EB – epidemiology

According to the data, it is estimated that 20 cases out of a million live births are diagnosed with EB, and 9 out of a million people in the general population have the disease. Of these cases, approximately 92% are epidermolysis bullosa simplex (EBS), 5% to epidermolysis bullosa dystrophica (EBD), 1% to epidermolysis bullosa junctionalis (EBJ) and 2% were not classified. The incidence rates range from 1 to 333 for EBJ, 1 to 450 for EBD, and the carrier frequency for EBS is presumably much higher than the previous two.

It should also be noted that the disorder occurs in all racial and ethnic groups and affects both genders.

EB disease – inheritance of a damaged gene

Vesicular epidermal separation is an inherited disease. Standard rules of genetics are at work here. If a child inherits a damaged recessive gene from his parents, he will not get the disease, but will be a carrier and will pass it on to his offspring in the future. EB disease will become active if the dominant gene is inherited.

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