Ataxia telangiectasia (A-T) is a severe autosomal recessive disorder that is caused by mutations in the ATM gene which codes for ataxia telangiectasia mutated (ATM), a pleiotropic kinase involved in DNA double-strand break recognition, activation of DNA repair proteins, and signaling in cell cycle checkpoint control [1-5]. The gene discussed is ATM; the disease is ataxia telangiectasia.