What Are Genodermatoses?
Genodermatoses are rare hereditary skin disorders that affect other organs. There are several genodermatoses, but common types of genodermatoses are ichthyosis, epidermolysis bullosa, ectodermal dysplasia, albinism, cutis laxa, progeroid, and precancerous conditions xeroderma pigmentosum, Rothmund Thomson syndrome, and dyskeratosis congenita. The type of disease is determined by how the genes are affected. They affect a person's quality of life and may cause death.
How Are Genodermatoses Classified?
Genodermatoses are inherited through modes:
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A Single Gene (Monogenic): A single gene abnormality is seen in such diseases.
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Polygenetic (Multiple Genes): Polygenic disorders include multiple gene abnormalities.
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Chromosomal: Refers to the diseases caused by a chromosomal abnormality.
What Are the Common Types of Genodermatoses?
Genodermatoses have many types. Most of them are rare.
The common types are:
Ectodermal Dysplasia
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Ectodermal dysplasia is a genetic disease due to the mutation or deletion of specific genes.
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It is characterized by a defect in the development or function of the teeth, hair, nails, and sweat glands.
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People with ectodermal dysplasia have abnormal nails, no or less sweating, abnormal or missing teeth, cleft lip, large forehead, low nasal bridge, thin hair, and poor hearing.
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It is a genetic disorder that can be inherited or passed down the family line.
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Their patterns of inheritance include x-linked recessive, autosomal dominant, and autosomal recessive.
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Out of 150 types of ectodermal dysplasia, the most common one is hypohidrotic dysplasia (caused by mutations in the EDA, EDAR, or EDARADD genes).
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Treatment: People with abnormal or no sweat gland function should live in ventilated areas at home, school, and work. Surgical procedures to repair the cleft palate may lessen facial deformities and improve speech. In addition, artificial tears may prevent corneal damage in people with dry eyes.
White Sponge Nevus
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There is a mutation in the keratin‑4 or keratin‑13 (genes that provide instructions for making proteins).
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It is characterized by thick, velvety sponge-like white patches of tissue (nevi) commonly found on the lining of the mouth (oral mucosa) and the inside of the cheeks (buccal mucosa).
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The condition inherits an autosomal dominant pattern (a copy of the altered gene in each cell causes the disorder).
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Treatment: Topical or systemic antibiotics may help in complete or partial remission.
Ichthyosis
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A disorder characterized by dry, thickened, scaly skin (fish-scale skin).
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It occurs due to genetic defects that alter the appearance and behavior of keratinocytes (skin cells) in the stratum corneum layer of the skin (outer layer).
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Most types of ichthyosis are rare. The two most common forms are:
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Ichthyosis Vulgaris: It manifests as gray, brown, or white scales on the skin in early childhood. Most types of ichthyosis are rare.
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X-linked Recessive Ichthyosis: It affects only males; women can be carriers. It can raise the risk of testicular cancer in males.
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Treatment: Treatment involves the management of dry and scaly skin by keeping it moist. Rub cream, lotion, or ointment on the skin daily. Take a bath with salt water. Use products containing salicylic acid, lactic acid, or glycolic acid.
Peutz-Jeghers Syndrome
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It is a condition that results from mutations in the STK11 gene (also known as the LKB1 gene) - the gene responsible for controlling cell growth.
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Symptoms include dark-colored spots (also called mucocutaneous pigmentation) on various body parts like the mouth, lips, eyes, nose, hands, feet, and anus. Also, there is a development of hamartomatous polyps (noncancerous overgrowths of tissue).
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Treatment: Close surveillance of organs to monitor for cancers may avoid emergencies.
Epidermolysis Bullosa
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Group of rare diseases caused by mutations in the COL7A1 gene (gene provides instructions for making subunits that form a more significant protein called type VII collagen).
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The disease causes blistering and fragile skin. The blisters arise due to rubbing, scratching, or minor trauma. Other symptoms include difficulty swallowing (dysphagia) and itchy and painful skin.
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The gene can either pass on from one parent with the disease (autosomal dominant inheritance) or from both parents (autosomal recessive inheritance). It may also arise due to a new mutation in the affected person.
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Three main types of the condition are:
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Epidermolysis Bullosa Simplex: A most common form of all types in which blistering occurs anywhere on the skin, mainly affecting the palms and the feet. The blisters usually heal without scarring.
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Junctional Epidermolysis Bullosa: A more severe condition in which blisters appear in infancy. A baby with this condition develops a hoarse-sounding cry and difficulty breathing due to the development of granulation tissues in the airway.
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Dystrophic Epidermolysis Bullosa: It occurs due to a defect in the gene responsible for producing a kind of collagen that provides strength to the dermis (underlying layer of the skin). In the absence of this collagen, the layers of the skin fail to join correctly.
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Treatment: Medications can help control pain and itching. Oral antibiotics can be considered if the wounds show widespread infection (fever, weakness). Skin grafting can be regarded as if scarring has affected the function of the hand. Repeated blistering and scarring can cause bends in the joints. Surgery can correct these conditions.
Ehlers–Danlos Syndrome
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A group of inherited conditions is associated with abnormal collagen production (a protein that is the main component of connective tissue).
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The affected areas are skin, joints, and blood vessels that lead to hyperflexible joints and stretchy, fragile skin.
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There are thirteen types of Ehlers–Danlos syndrome, out of which the common types are:
- Vascular Ehlers-Danlos Syndrome: Occurs due to rupture of blood vessels and organs, leading to bleeding problems. Some complications may lead to bruising, internal bleeding, or stroke. Most cases of this vascular type of Ehlers-Danlos syndrome result from alterations in the COL3A1 gene.
- Classical Ehlers-Danlos Syndrome: People with this type have characteristic "cigarette paper scars" due to the wounds that split open with bleeding and leave scars that widen over time alterations in the genes COL5A1 or COL5A1, or COL5A2 cause the classical type cases.
- Cardiac-Vascular Ehlers-Danlos Syndrome: Those with cardiac-vascular type experience severe problems with the valves that control blood movement through the heart. It involves mutations in the TNXB gene.
- Kyphoscoliotic Type: Occurs due to mutations in the PLOD1M or FKBP14 genes. People with this type experience curvature in their spines.
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Treatment: Over-the-counter pain relievers such as Acetaminophen, Ibuprofen, and Naproxen sodium are the mainstay of treatment. Low blood pressure helps reduce the stress on fragile blood vessels in some forms of Ehlers-Danlos syndrome.
Multiple Hamartoma Syndrome
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Changes in the genes - PTEN, KLLN, and WWP1 cause this disease. It is also known as Cowden syndrome, characterized by numerous non-cancerous, tumor-like growths (hamartomas).
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These tumor-like growths are most commonly found on the skin, mucous membranes, intestine, and other body parts.
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People with this disease are at increased risk of developing melanoma and colorectal and kidney cancers.
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Treatment: People with this condition should undergo annual medical and physical examinations, laboratory tests, and radiographic tests to check for internal malignancies. Genetic counseling is mainly for women to reduce the risk of complications. Oral retinoids may help treat skin lesions temporarily. Surgeries like chemical peeling, laser resurfacing, or shave excisions may be considered.
Xeroderma Pigmentosum
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Inherited skin condition caused due to extreme sensitivity to sunlight.
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The affected areas are sun-exposed body parts such as the face, arms, and lips.
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In people with xeroderma pigmentosum, DNA damage is not repaired on its own due to the mutations in genes involved in repairing damaged DNA. As a result, many abnormalities form in DNA, cells malfunction, and later become cancerous or die.
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People with this condition experience sunburn with blistering, dark or light-colored patches, and dry skin and eyes. They have more risk of developing cancers.
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This condition inherits in an autosomal recessive pattern. The parents of an individual with an autosomal recessive disorder carry one copy of the mutated gene. Still, they do not show signs and symptoms of the disease.
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Treatment: Avoid ultraviolet radiation exposure like cigarette smoke, sunlight, and others. People with xeroderma pigmentosum may require regular screening for cancer.
Conclusion
Genodermatoses are rare diseases for which effective treatment still does not exist. Currently, the treatment modalities are based on managing the symptoms comprising topical preparations, surgery, symptomatic pain relief, itching treatment, and complications like skin cancers. One of the biggest challenges in treating genodermatoses is multiple organ involvement. Recent technological advances offer new inventive tools that help target the real cause of genodermatoses and thus restore or replace the affected gene. Therapies emerging as powerful tools to treat genodermatoses are gene replacement, genome editing, protein replacement, and cell-based and RNA-based therapies. However, despite all the advancements, therapeutic approaches still have much scope for improvement.