Mutations in ataxia telangiectasia patients are well characterized: over 200 different ATM mutations have been described, and approximately 85% of the mutants reported in ataxia telangiectasia patients are predicted to truncate the protein, but the mutations are mapped uniformly over the gene, which includes the N-terminal region truncated in the short isoform [41,42]. Here, ATM is linked to ataxia telangiectasia.