SNP Shot: Genomic Insights

Melanoma is a skin cancer that originates in melanocytes, the cells responsible for producing pigment. While it's a skin cancer, melanoma isn't always found in areas heavily exposed to the sun. In men, it's most often located on the back, and in women, on the legs. Although usually found on the skin (cutaneous melanoma), about 5% of the time it can arise in melanocytes within other tissues, such as the eyes (uveal melanoma) or the mucous membranes lining body cavities, like the mouth (mucosal melanoma). It can occur at any age, but is most prevalent in people aged fifty to seventy, and is increasingly seen in teenagers and young adults.

Melanoma can arise from an existing mole or other skin growth that transforms into cancer (becomes malignant). However, many melanomas are new growths. They typically have uneven borders and an irregular shape, and their size can vary from millimeters to centimeters. The color of melanomas can also differ, ranging from brown and black to red, pink, blue, or white.

Initially, most melanomas are confined to the epidermis, the outermost layer of skin. However, if the melanoma thickens and extends deeper into the skin, it has the potential to spread (metastasize) to other parts of the body.

Having a high number of moles or other pigmented skin growths, usually more than 25, is linked to a higher risk of developing melanoma. It's also a common characteristic of genetic syndromes affecting the skin, like xeroderma pigmentosum. Furthermore, individuals with a history of melanoma are significantly more likely (approximately nine times) to develop it again compared to the general population. The estimated 5-year survival rate for melanoma is about 90%.

Inheritance:

The majority of melanoma cases are sporadic, meaning they occur without a known family history of the disease. In familial cases, shared environmental and/or genetic factors may play a role. The genetic factors usually follow an autosomal dominant inheritance pattern, where inheriting just one copy of the altered gene increases the risk of melanoma. When melanoma is part of a genetic syndrome, its inheritance pattern mirrors that of the underlying syndrome.