Epidemiology: Ataxia-Telangiectasia prevalence is estimated between 1 in 40,000 and 1 in 100,000.^[1] Some studies have shown that the prevalence of A-T among adults younger than age 50 is approximately 1 in 500,000. Some mutations are more common than others is certain geographical regions for example, the 7636del9 mutation is a common mutation in European populations which has been shown to increase the risk of breast cancer in carriers.

Etiology: Ataxia-Telangiectasia is caused by mutations in the ATM (Ataxia Telangiectasia, Mutated) gene which encodes a protein of the same name. The primary role of the ATM protein is coordination of cellular signaling pathways in response to DNA double strand breaks, oxidative stress and other genotoxic stress.