Epidermolysis
bullosa (EB) is a rare genetic disorder that causes skin and mucous membrane
fragility. It comprises a clinically and genetically heterogeneous group
of disorder characterized by spontaneous or contact/friction–induced
blistering. EB is classified into 4 types–simplex, junctional,
dystrophic, and Kindler syndrome–and 30 sub-types. The disease is caused
by defects in proteins implicated in dermal-epidermal adhesion. To-date, at least
19 genes have been characterized and more than 1000 mutations
identified, thus making it a very diagnosis disorder.
Clinical Classification of EB
EBS Suprabasal- Skin fragility syndromes:
Acral Peeling Skin Syndrome (APSS) [Protein- Transgluminase 5]
common features: characterized by painless peeling of the top layer of skin. The term
"acral" refers to the fact that the skin peeling in this condition is
most apparent on the hands and feet. Occasionally, peeling also occurs
on the arms and legs. The peeling is usually evident from birth,
although the condition can also begin in childhood or later in life.
Skin peeling is made worse by exposure to heat, humidity and other forms
of moisture, and friction. The underlying skin may be temporarily red
and itchy, but it typically heals without scarring. Acral peeling skin
syndrome is not associated with any other health problems.
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EBS Superficialis (EBSS) [Protein- unknown]
common features: milia and atrophic (indented) scarring, as well as involvement of oral and/or ocular surfaces. the presence of blisters and the absence of spontaneous continual exfoliation or peeling.
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Lethal Acantholytic EBS (EBS- acanth) [Protein- Desmoplaskin, Plakoglobin]
common features: characterized by
generalized oozing erosions, usually in the absence of blisters.
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Desmoplaskin Woolly Hair Syndrome [Protein- Desmoplaskin]
common features: hair that is unusually coarse, dry,
fine, and tightly curled. In some cases, the hair is also sparse. The
woolly hair texture typically affects only scalp hair and is present
from birth. Starting early in life, affected individuals also develop
palmoplantar keratoderma, a condition that causes skin on the palms of
the hands and the soles of the feet to become thick, scaly, and
calloused; Cardiomyopathy, which is a disease of the heart muscle,
is a life-threatening health problem that can develop in people with
keratoderma with woolly hair. Unlike the other features of this
condition, signs and symptoms of cardiomyopathy may not appear until
adolescence or later. Complications of cardiomyopathy can include an
abnormal heartbeat (arrhythmia), heart failure, and sudden death.
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Plakoglobin Deficiency [Protein - Plakoglobin]
common features: mild skin involvement, thickening of the skin on the palms of the hands and soles of the feet and arrhythmogenic heart disease.
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Ectodermal Dysplasia Syndrome [Protein Plakophilin 1]
common features: manifests with skin fragility, palmoplantar keratoderma, abnormal hair growth, and nail dystrophy and, in some but not all cases, with defective sweating
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EBS Basal- More common type of EBS
Localized EBS (EBS-loc) [Protein- Keratin 5 or Keratin 14]
common features: most
common form; rarely present at birth and usually appear when the child begins to crawl or walk; characterized by blisters confined to the palms
and soles and, in some cases, by oral erosions or blisters during
infancy. Lesions can be present in any part of the body as a result of
skin trauma.
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Generalized Intermediate EBS (EBS-gen intermed) [Protein- Keratin 5 or Keratin 14]
common features: usually present at birth or within the first days of life; presents with non-herpetiform blisters (not in clusters); anemia and growth retardation are uncommon in this subtype.
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Generalized Severe EBS (EBS- gen sev) [Protein- Keratin 5 or Keratin 14]
common features: a
less frequent subtype; present at birth with widespread skin loss; usually associated with marked morbidity and
mortality during the neonatal period or early infancy. Its most
distinctive feature is the formation of intact blisters grouped in an
arch-shaped or clustered distribution (herpetiform). Patients with this form usually
develop skin thickening on the palms and soles, giving rise to keratosis
that may resolve on reaching adulthood. Some patients have nail
distrophy atrophic scarring, milia, mucosal involvement (laryngeal
stenosis), anemia, and delayed growth.
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EBS with Mottled Pigmentation (EBS-MP) [Protein- Keratin 5]
common features: blistering may begin at birth; have a mottled appearance of the skin; may bruise more easily and the skin may seem to age more quickly.
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Migratory Circinate EBS (EBS-migr) [Protein- Keratin 5]
common features: appears to be phenotypically milder than
EBS-generalized severe; is characterized by belt-like areas of
erythema with multiple vesicles and small blisters at the advancing edge
of erythema. Lesions appear from birth primarily on hands, feet and
legs. Nails and mucosa were not affected. The lesions healed with brown
pigmentation, but without scarring.
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KLHL24 EBS [Protein-Keratin 14]
common feature: wide spread blistering can occur;
alopecia (a condition that causes hair to fall out in small patches); follicular and cutaneous atrophy (reduced hair follicles and
sebaceous glands) and most significantly-
Dilated cardiomyopathy- a condition in which the heart becomes enlarged and cannot pump
blood effectively. Symptoms vary from none to feeling tired, leg
swelling, and shortness of breath. It may also result in chest pain or
fainting.
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K14 Recessive EBS (EBS-AR) [Protein- Keratin 14]
common features: characterized by generalized or, less frequently, localized acral (hands, feet, fingers, toes) blistering.
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EBS with Muscular Dystrophy (EBS-MD) [Protein- Plectin 1]
common features: generalized blistering associated with muscular dystrophy.
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EBS with Pyloric Atresia (EBS-PA) [Protein- Plectin, Alpha4Beta6]
common features: generalized severe blistering with widespread congenital absence of skin and pyloric atresia.
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Ogna EBS (EBS-Og) [Protein- Plectin]
common features: characterized by sometimes widespread, primarily acral blistering.
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Recessive EBS BP230 Deficiency (EBS-AR BP230) [Protein- antigen-1 BP230]
common features: mild, predominantly acral, trauma-induced skin fragility, resulting in
blisters. Blisters mostly affect the feet, including the dorsal side,
and are often several centimeters big.
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Recessive EBS Exophilin 5 Deficiency (EBS-AR exo 5) [Protein Exophilin 5]
common features: mild, generalized trauma-induced scale crusts and intermittent
blistering, sometimes combined with erosions and bleeding, recovering
with slight scarring and post-inflammatory hyperpigmentation. Clinical
symptoms improve with age.
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