Epidermolysis Bullosa (EB) is a family of life-threatening rare genetic disorders that affect the body’s largest organ: the skin.
Individuals with EB lack critical proteins that bind the skin’s two layers together. Without these proteins, the skin tears apart, blisters, and shears off leading to severe pain, disfigurement, and wounds that may never heal.
EB is a family of genetic disorders
EB is not specific to any ethnicity or gender
EB is not contagious
EB is a chronic disease
EB is estimated to affect 500,000 people worldwide
EB SUBTYPES
EB Simplex (EBS)
Junctional EB (JEB)
Dystrophic EB (DEB)
Kindler Syndrome
EB Simplex (EBS)
EB Simplex (EBS) is the most common form of EB. Blisters form in the epidermis, or outer layer of skin. It is caused by mutations in the genes KRT5 or KRT14, which hold the instructions to make the proteins keratin 5 and keratin 14, respectively. There are 4 major types of EBS: Localized, Dowling-Meara, Generalized, and EBS with Mottled Pigmentation. Depending on the subtype, individuals with EBS experience mild to severe symptoms. Blisters are commonly found on the hands and feet, but can be widespread.
Junctional EB (JEB)
In individuals with Junctional EB (JEB), blisters form between the dermis and epidermis, in the basement membrane zone (BMZ). These blisters occur both on the skin and inside of the body. JEB is caused by mutations in the genes LAMA3, LAMB3, or LAMC3, which hold the instructions to make the protein laminin 332, and the gene COL17A1, which holds the instructions to make the protein collagen 17. There are 2 main subtypes, Herlitz and Non-Herlitz JEB. Herlitz JEB causes severe symptoms and is often fatal in infancy. It is considered the most serious form of the disorder. Non-Herlitz EB causes milder symptoms and individuals with this type have a normal life expectancy.
Dystrophic EB (DEB)
Dystrophic EB (DEB) causes blistering in the dermis, the inner layer of the skin. Symptoms range from mild to severe. DEB is caused by mutations in the gene COL7A1, which holds the instructions to make the protein collagen 7. There are 2 main subtypes: Dominant (DDEB) and Recessive (RDEB). DDEB causes blistering generally on the hands, elbows, knees, and feet. RDEB causes blisters both on the skin and inside the body. Individuals with RDEB have an increased risk for squamous cell carcinoma, and their life expectancy is age 30. RDEB is considered one of the most severe forms of EB.
Kindler Syndrome
Kindler Syndrome is the rarest type of EB. Blisters form in any skin layer and internal organs. Kindler Syndrome is caused by mutations in the gene FERMT1, which holds the instructions to make the protein kindlin-1. Individuals with Kindler Syndrome have a high sensitivity to UV rays from the sun and have an increased risk for squamous cell carcinoma, especially in the mouth.
HEREDITY OF EB
Genetic disorders, like EB, are usually passed down from parents to offspring, although they are rarely caused by a spontaneous DNA mutation. EBS and DDEB are passed down through dominant inheritance. This means only one copy of the mutated gene, from either the mother or father, is needed for a child to express the disorder. RDEB, JEB, and Kindler Syndrome are all passed down through recessive inheritance. This means that a child needs to get 2 copies of the mutated gene, one from each parent, to express the disease. Children can also be carriers of the gene, which means they’re able to pass it down to their children, but do not express the disorder.
SOURCES
“Epidermolysis Bullosa Simplex – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health, 2018
ghr.nlm.nih.gov/condition/epidermolysis-bullosa-simplex
“Junctional Epidermolysis Bullosa – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health, 2018
ghr.nlm.nih.gov/condition/junctional-epidermolysis-bullosa
“Dystrophic Epidermolysis Bullosa – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health, 2018
ghr.nlm.nih.gov/condition/dystrophic-epidermolysis-bullosa
“Kindler Syndrome – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health, 2018
ghr.nlm.nih.gov/condition/kindler-syndrome
“Dominant Dystrophic Epidermolysis Bullosa.” Genetic and Rare Diseases Information Center, U.S. Department of Health and Human Services
rarediseases.info.nih.gov/diseases/2139/dominant-dystrophic-epidermolysis-bullosa
Yancey, Kim B., and Helmut Hintner. “Non-herlitz junctional epidermolysis bullosa.” Dermatologic clinics 28.1 (2010): 67-77.