Polymorphic variations of theATMgene. (A) DNA sequence electrophoretograms with arrows showing the positions of the heterozygous germ line SNPs at 4365T>A in patient HD1, 4949A>G in patients HD2 and HD3, 4138C>T in patient HD4, and 2127T>C in patient HD5. The first codon of the ORF was designated +1. “N” represents indistinguishable nucleotides. (B) Schematic diagram of the ATM protein. The locations of amino acid changes are indicated by arrows in relation to the predicted domains. (C) Schematic diagram of variant species of ATM mRNA found in cells from patient HD6.