CDKN2A

MedlinePlus Genetics provides information about Bladder cancer

Mutations in the CDKN2A gene are found in up to one-quarter of head and neck squamous cell carcinomas (HNSCC). This type of cancerous tumor occurs in the moist lining of the mouth, nose, and throat. CDKN2A gene mutations associated with this condition are acquired during a person's lifetime and are found only in tumor cells; these changes are known as somatic mutations. Most of these mutations lead to production of little or no functional p16(INK4A) protein. Without p16(INK4A) to regulate cell growth and division (proliferation), cells can continue to grow and divide without control, which can lead to tumor formation.

A different type of alteration involving the CDKN2A gene can result in reduced amounts or an absence of the p16(INK4A) or p14(ARF) protein. This alteration, known as promoter hypermethylation, turns off the production of p16(INK4A) or p14(ARF). Without one of these tumor suppressors, cells can grow and divide unchecked, leading to the development of cancer.

MedlinePlus Genetics provides information about Lung cancer

Mutations in the CDKN2A gene are also associated with melanoma, a type of skin cancer that begins in pigment-producing cells called melanocytes. CDKN2A gene mutations are found in up to 40 percent of familial cases of melanoma, in which multiple family members develop the cancer. These mutations, classified as germline mutations, are typically inherited and are present in essentially all of the body's cells. The CDKN2A gene mutations found in melanoma result in a nonfunctional p16(INK4A) protein. In many cases, a second, somatic mutation occurs in the normal copy of the gene in melanocytes. In about half of melanomas, part or all of the CDKN2A gene is missing (deleted). In many other cases, the CDKN2A gene has a mutation or is turned off (inactive). Somatic mutations in other genes involved in cell growth are also needed for a melanoma to develop. Together, the germline and somatic mutations impair the function of proteins that regulate division and senescence, leading to uncontrolled cell growth and the formation of a melanoma.

Individuals with a CDKN2A gene mutation tend to develop melanoma at an earlier age than those without a mutation in the gene. They also tend to develop other cancers during their lifetime, particularly cancers of the pancreas or lung.

Germline mutations affecting the CDKN2A gene are associated with other cancers, including breast cancer and pancreatic cancer. In some families, CDKN2A gene mutations are associated with development of only one type of cancer. In other families, mutations can lead to a cancer predisposition syndrome, which increases the risk of developing multiple types of cancer. CDKN2A gene mutations involved in cancer impair production of functional p16(INK4A) or, less commonly, p14(ARF), which can result in uncontrolled cell growth and tumor formation.

Somatic CDKN2A gene mutations have been found in some people with brain tumors and in children with a blood cancer called acute lymphoblastic leukemia.