Genetic Monitoring of Human Polymorphic Cancer Susceptibility Genes by Polymerase Chain Reaction: Application to Glutathione Transferase μ

Several genes involved in the metabolism of carcinogens have been found to be polymorphic in human populations and are associated with increased risk of cancer at some sites. This study focuses on the polymorphic enzyme glutathione transferase μ (GT μ). Smokers with low lymphocyte GT μ activity are at an approximately 2-fold higher risk for lung cancer and an approximately 3-fold higher risk for stomach and colon adenocarcinomas. Recent cloning and sequencing of the GST1 gene has allowed the development of convenient genotyping methods based on restriction fragment length polymorphisms (RFLP) or the polymerase chain reaction (PCR). The GST1 polymorphism has been shown to be a deletion of the gene locus. To detect the presence or absence of the gene we amplified exons 4-5 and/or exons 6-7 of the GST1 gene by PCR. PCR amplification produced bands of 215-bp or 273-bp from individuals with one or two copies of the GST1 allele and no band if the individual was homozygously deleted (0/0). In the exon 6-7 PCR, we co-amplified a 268-bp portion of the β-globin gene as an internal reference standard for quantitative analysis of product yield. This allowed homozygote individuals (+/+) to be distinguished from heterozygotes (+/0). We have compared the GST1 genotype to lymphocyte GT μ activity measured on trans-stilbene oxide (TSO) in the lymphocytes of 45 individuals. Low GT μ activity ($