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Multiple familial trichoepithelioma
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Reviewed June 2012
What is multiple familial trichoepithelioma?
Multiple familial trichoepithelioma is a condition involving multiple skin tumors that develop from structures associated with the skin (skin appendages), such as hair follicles and sweat glands. People with multiple familial trichoepithelioma typically develop large numbers of smooth, round tumors called trichoepitheliomas, which arise from hair follicles. Trichoepitheliomas are generally noncancerous (benign) but occasionally develop into a type of skin cancer called basal cell carcinoma.
Individuals with multiple familial trichoepithelioma occasionally also develop other types of tumors, including growths called spiradenomas and cylindromas. Spiradenomas develop in sweat glands. The origin of cylindromas has been unclear; while previously thought to derive from sweat glands, they are now generally believed to begin in hair follicles. Affected individuals are also at increased risk of developing tumors in tissues other than skin appendages, particularly benign or malignant tumors of the salivary glands.
People with multiple familial trichoepithelioma typically begin developing tumors during childhood or adolescence. The tumors mostly appear on the face, especially in the folds in the skin between the nose and lips (nasolabial folds, sometimes called smile lines), but may also occur on the neck, scalp, or trunk. They may grow larger and increase in number over time.
In severe cases, the tumors may get in the way of the eyes, ears, nose, or mouth and affect vision, hearing, or other functions. The growths can be disfiguring and may contribute to depression or other psychological problems. For reasons that are unclear, females with multiple familial trichoepithelioma are often more severely affected than males.
How common is multiple familial trichoepithelioma?
Multiple familial trichoepithelioma is a rare disorder; its prevalence is unknown.
What genes are related to multiple familial trichoepithelioma?
Multiple familial trichoepithelioma can be caused by mutations in the CYLD gene. This gene provides instructions for making a protein that helps regulate nuclear factor-kappa-B. Nuclear factor-kappa-B is a group of related proteins that help protect cells from self-destruction (apoptosis) in response to certain signals. In regulating the action of nuclear factor-kappa-B, the CYLD protein allows cells to respond properly to signals to self-destruct when appropriate, such as when the cells become abnormal. By this mechanism, the CYLD protein acts as a tumor suppressor, which means that it helps prevent cells from growing and dividing too fast or in an uncontrolled way.
People with CYLD-related multiple familial trichoepithelioma are born with a mutation in one of the two copies of the CYLD gene in each cell. This mutation prevents the cell from making functional CYLD protein from the altered copy of the gene. However, enough protein is usually produced from the other, normal copy of the gene to regulate cell growth effectively. For tumors to develop, a second mutation or deletion of genetic material involving the other copy of the CYLD gene must occur in certain cells during a person's lifetime.
When both copies of the CYLD gene are mutated in a particular cell, that cell cannot produce any functional CYLD protein. The loss of this protein allows the cell to grow and divide in an uncontrolled way to form a tumor. In people with multiple familial trichoepithelioma, a second CYLD mutation typically occurs in multiple cells over an affected person's lifetime. The loss of CYLD protein in these cells leads to the growth of skin appendage tumors.
Some researchers consider multiple familial trichoepithelioma and two related conditions called familial cylindromatosis and Brooke-Spiegler syndrome, which are also caused by CYLD gene mutations, to be different forms of the same disorder. It is unclear why mutations in the CYLD gene cause different patterns of skin appendage tumors in each of these conditions, or why the tumors are generally confined to the skin in these disorders.
Some people with multiple familial trichoepithelioma do not have mutations in the CYLD gene. Scientists are working to identify the genetic cause of the disorder in these individuals.
Read more about the CYLD gene.
How do people inherit multiple familial trichoepithelioma?
Susceptibility to multiple familial trichoepithelioma has an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell increases the risk of developing this condition. However, a second, non-inherited mutation is required for development of skin appendage tumors in this disorder.
Where can I find information about diagnosis or management of multiple familial trichoepithelioma?
These resources address the diagnosis or management of multiple familial trichoepithelioma and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about multiple familial trichoepithelioma?
You may find the following resources about multiple familial trichoepithelioma helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for multiple familial trichoepithelioma?
What if I still have specific questions about multiple familial trichoepithelioma?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding multiple familial trichoepithelioma?
apoptosis ; autosomal ; autosomal dominant ; benign ; cancer ; carcinoma ; cell ; deletion ; depression ; epithelioma ; familial ; gene ; inheritance ; mutation ; pattern of inheritance ; prevalence ; protein ; susceptibility ; syndrome ; tumor
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (11 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.