Genetic polymorphisms of CYP2E1 and GSTM1 in a Thai population.

Cytochrome P450 2E1 and GSTM1 play major roles in metabolic activation and detoxification of many carcinogens and polymorphisms in the encoding genes have been reported to be individually associated with increased susceptibility to certain cancer. In the present study, we investigated the RsaI, PstI and DraI polymorphisms of the CYP2E1 gene and the null GSTM1 genotype in a Thai population. DNA samples from 485 individuals were analysed by polymerase chain reaction with restriction fragment length (PCR/RFLP). The frequency of RsaI and PstI predominant homozygous alleles (c1/c1) was 73.2%, heterozygous allele (c1/c2) was 25.6% and rare homozygous allele (c2/c2) was 1.2%. For the DraI polymorphism, the frequency of the predominant allele (DD) was 59.6%, heterozygous (CD) was 40% and rare allele (CC) was 0.4%. The frequency of GSTM1 null genotype was 62.7%. The distribution and frequencies of these alleles showed different pattern from those found in Caucasian and some other Asian populations. With the large population in this study, we believed that our results are reliable estimates of the frequencies of the polymorphic CYP2E1 and GSTM1 alleles in Thai population and should provide a base for further epidemiological studies on their links with cancer development.