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EB - blistering epidermal separation

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EB - blistering epidermal separation

PantherMedia

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EB, or bullous epidermal separation, is a genodermatosis, a disease caused by mutations in the genes that code for the proteins responsible for the connections between the various layers of skin. The range of symptoms is very wide and depends on both the gene, the type of mutation, its location and the type of disease, which can appear as early as foetal life, but unfortunately also in any other phase of life.

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Table of contents:

  1. Types of EB
  2. Symptoms
  3. Oral manifestation of the disease

EB, or bullous epidermal separation, belongs to a group of diseases in which the basis for development is genetics. It is a condition that manifests itself by the appearance of blisters on the skin. They are caused by abnormal connections between the different layers of the dermis or epidermis, depending on the type of disease that affects the individual. The defect is an abnormality of reaction. This means that, either spontaneously or as a result of a slight trauma, lesions appear on the skin in the form of blisters. According to statistics, 1 person/ 50000 live births is affected - so it is a relatively rare condition [1].

The abnormal behaviour of the skin, manifested by the formation of blisters, is the result of a mutation in one of the 14 genes encoding proteins that are key to the normal processes of connecting the individual layers of the skin to each other [1]. Depending on the type of disease, gene, type and location of the mutation, the condition is inherited in an autosomal recessive or dominant manner [2].

How a type of EB progresses and how it will be classified depends on the type of mutation and the degree of damage to the structural protein. The main types of this condition are:simplex EB,junctional EB,dystrophic EB and mixed EB,Kindler syndrome, of which there are about 30 more subtypes [1]

Types of EB

EB simplex, the simple type of bullous epidermolysis bullosa, results from mutations in the KRT 5 and KRT 14 protein genes, which are responsible for creatine 5 and 14 synthesis. This type is usually inherited in an autosomal dominant manner and the lesions occur at the level of the basal layer of the epidermis.

EB junctional is a combined type of bullous skin detachment associated with mutations in the LMAA3, LMAB3, LMAC2, COL17A1, ITGA6 or ITGB4 genes. These genes are responsible for the normal synthesis of laminin-5, and the mode of inheritance is autosomal recessive. The site of blister formation is the bright basement membrane layer, which is slightly deeper than in the normal type.

EB dystrohic is a dystrophic type of disease that results from mutations in the COL7A1 gene, without which collagen cannot be synthesised properly. It can be inherited in a recessive as well as a dominant manner, and the site of blister formation is the sublamina densa layer and the skin, which is the deepest area [1].

Most of the lesions occur sporadically and are characteristic within a family, but a notable regularity is that some mutations occur with greater frequency than others in a particular population [2].

EB mixed - Kindler syndrome, a type of mixed disorder that occurs very rarely and is the result of mutations in the KIND1 gene, a protein that encodes kindlin-1, and can be inherited in an autosomal recessive manner. This type is complicated by the fact that the blisters are essentially unlimited in their ability to form within the different layers of the epidermis [1].

Blistering-separation-of-epidermis, Connections-between-skin-layers, Eb, Mutations-of-protein-coding-genesMedical diagnosis, photo: panthermedia

With this subgroup, maintaining expression of a single gene even at a low level, the disease is severe, but not lethal - nevertheless, age-duration of up to 70-80 years is noted in these patients [2].

Symptoms

In the case of bullous epidermolysis bull osa, it is not really possible to speak of a pattern, as the spectrum of symptoms is extremely wide, the course varies, as does the severity and location, all depending on the type of condition we are dealing with and therefore the type of mutation.

Blisters can appear as isolated lesions that heal easily, but they can also be chronic erosions, either locally or throughout the body. Characteristics include generalised blistering, either spontaneously or as a result of minor trauma, usually around the elbows, feet, hands and knees. The appearance of blisters also varies and may be serous or haemorrhagic. The time of onset of these pathological changes is not fully defined, and specialists even speak of fetal life as the beginning of the disease or the time just after birth. However, it is possible that the first symptoms become apparent in early childhood or later in life, depending on the type of disease. Thus, as can be seen, there are no clear age limits regarding the onset of the disease or the symptoms that could indicate its development.

In addition to blistering lesions, other types of skin lesions may form on the skin, such as prosacchiae, hyperpigmentation, scars or erosions. Lesions in the form of epidermal defects or problems with nail plates, alopecia or adhesions and contractures on the fingers and toes are also possible. Unfortunately, the formation of neoplastic lesions on the skin due to pathological processes in the skin also occurs, especially in old age. However, the changes that accompany EB do not only affect the skin; they may also affect the mucous membranes of the gastrointestinal tract, urinary tract and lungs, leading to erosions or strictures [1].

Oral manifestation of the disease

The mucous membranes in the oral cavity are not unaffected by EB. Blistering that occurs there - on the cheeks, palate or tongue - results in scarring, distortion and adhesions. Patients suffering from bullous epidermal separation may also have problems with underdevelopment of the jaw, a shortened midface, limited mouth opening, a short labial fissure or a shallow oral vestibule as a consequence of the resulting scarring. The appearance of lesions is strongly linked to wound healing, which can develop into ulcerations of the mucous membrane, cause inflammation of the lip corners or fungal infections. It is not only the mucous membranes that are affected - the teeth can also be affected. White spots may appear on teeth, indicating demineralisation of the enamel. Many times, patients also show delayed tooth formation and decay problems with high plaque build-up, which is compounded by negligent hygiene. Unfortunately, in the case of EB sufferers, even simple daily tooth brushing can become the cause of new blisters. An additional problem is scarring and adhesions in the fingers - as this makes it much more difficult to hold the toothbrush correctly in the hand, resulting in inaccurate and insufficient cleaning [1].