ATM

Researchers have identified several hundred variants (also called mutations) in the ATM gene that cause ataxia-telangiectasia. This disorder is characterized by progressive difficulty with coordinating movements (ataxia) beginning in early childhood. People with this disorder have variants in both copies of the ATM gene in each cell. Most of these variants disrupt protein production, resulting in an abnormally small, nonfunctional version of the ATM protein. Cells without any functional ATM protein are hypersensitive to radiation and do not respond normally to DNA damage. Instead of activating DNA repair, the altered ATM protein allows variants to accumulate in other genes, which may cause cells to grow and divide in an uncontrolled way. This kind of unregulated cell growth can lead to the formation of cancerous tumors. In addition, ATM gene variants can allow cells to die inappropriately, particularly affecting cells in a part of the brain involved in coordinating movements (the cerebellum). This loss of brain cells causes the movement problems characteristic of ataxia-telangiectasia.

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Research suggests that people who carry one alterd copy of the ATM gene in each cell may have an increased risk of developing several other types of cancer. In particular, some studies have shown that cancers of the breast, stomach, bladder, pancreas, lung, and ovaries occur more frequently in ATM gene variant carriers than in people who do not carry these variants. The results of similar studies, however, have been conflicting. Additional research is needed to clarify which other types of cancer, if any, are associated with ATM gene variants.