USE OF SITE-DIRECTED MUTAGENESIS OF ALLELE-SPECIFIC PCR PRIMERS TO IDENTIFY THE GSTM1-A, GSTM1-B, GSTM1-A,B AND GSTM1 NULL POLYMORPHISMS AT THE GLUTATHIONE-S-TRANSFERASE, GSTM1 LOCUS

We describe the identification of the GSTM1 null, GSTM1 A, GSTM1 B and GSTM1 A,B polymorphisms at the glutathione S-transferase GSTM1 locus using a single-step PCR method. Target DNA was amplified using primers to intron 6 and exon 7 with site-directed mutagenesis being used to introduce a restriction site in DNA amplified from GSTMI *A, thereby allowing differentiation of this allele and GSTM1 *B. The accuracy of this approach in identifying the GSTM1 A, GSTM 1 B, GSTM 1 A,B and GSTM 1 null polymorphisms was confirmed by comparison with, firstly, an established PCR method that distinguishes GSTM1 *0 homozygotes from individuals with the other GSTM1 genotypes and, secondly, GSTM1 phenotypes determined using chromatofocusing.