The Genetics of Skin Cancer
Forty to 50 percent of 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 59 people 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 (90 percent) are due to environmental factors such as ultraviolet radiation (sun exposure). However, about 5 percent 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 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/dysplastic nevus syndrome is caused by a gene on chromosome 9, known as p16, or CDKN2A. This condition accounts for about 20 percent of the familial cases of melanoma. Mutations in p16 result in unregulated cell growth. Persons with a p16 mutation have an increased lifetime risk to develop melanoma (50 percent or more) as well as an increased risk (approximately 17 percent) to develop pancreatic cancer. Genes on chromosomes 1 and 12 have also been found to be involved in familial cases of melanoma.