The Genetics of Skin Cancer
Many Americans who live to the age of 65 will have skin cancer at least once. The most common types of skin cancer in the United States are basal cell and squamous cell carcinomas. These are referred to as nonmelanoma skin cancers and are generally the result of sun exposure.
Approximately one in 50 whites, one in 1,000 blacks, and one in 200 Hispanics will develop melanoma during their lifetime. Malignant melanoma is a cancer that begins in the melanocytes, the pigment-producing cells in the skin. The majority of melanoma cases are due to environmental factors, such as ultraviolet radiation (sun exposure). However, about five to 10 percent of cases occur in people with a family history of melanoma. In some of these families, the risk to develop melanoma will be inherited in an autosomal dominant fashion. In other words, parents with a gene mutation have a 50/50 chance to pass on the susceptibility to each of their children regardless of gender.
One type of hereditary melanoma, called the familial cutaneous malignant melanoma or dysplastic nevus syndrome is caused by a change (mutation) in a gene on chromosome 9, known as p16, or CDKN2A. This condition accounts for about 40 percent of the familial cases of melanoma. Mutations in p16 result in unregulated cell growth. People with a p16 mutation have an increased lifetime risk to develop melanoma (as high as 50 percent or more) as well as an increased lifetime risk (as high as 17 percent) of developing pancreatic cancer. Genes on chromosomes 1 and 8 may also be involved in familial cases of melanoma.