ATM and Ataxia-telangiectasia: The reason that ATM has received so much attention is that patients with the recessive disease ataxia-telangiectasia, due to a mutation in the ATM gene, have a 100-fold increased risk of cancer[33,34] and obligate heterozygous carriers of ATM mutations may have an increased risk of cancer, particularly breast cancer [35-39], although this finding is controversial[40,41].