Ataxia-telangiectasia, Nijmegen breakage syndrome and ataxia-telangiectasia-like disorder are defective in the ataxia-telangiectasia mutated (ATM) [56], NBS1 [57,58] and Mre11 [59] genes, respectively. The gene discussed is ATM; the disease is ataxia-telangiectasia-like disorder.