Combined genotype analysis of GSTM1 and GSTT1 polymorphisms in a Polish population

This study describes the distribution of GSTT1 and GSTM1 polymorphisms in a normal population of central Poland. A homozygous inherited deletion of either gene leads to absence of enzyme activity in affected individuals, and those lacking more than one detoxifying gene are at the highest risk for diseases caused by environmental factors. The prevalence of the "null" genotype of the GSTM1 and GSTT1 genes was determined by using a multiplex polymerase chain reaction methodology in a group of 233 healthy individuals. We found the following frequencies of individuals with mutated alleles: 47.6% were homozygously deficient for GSTM1 (51.1% males, 42.4% females) and 16.3% for GSTT1 (17.7% males, 15.2% females). The combined analyses GSTM1/GSTT1 revealed the following genotypes: +/+, 44.2% (42.6% males, 46.7% females); "null"/+, 39.1% (39.7% males, 38.0% females); +/"null," 8.6% (7.1% males, 10.9% females); "null"/"null," 8.1% (10.6% males, 4.4% females). Of interest is the small number of women lacking both genes. Significant differences occurred between men and women in some age groups, which could suggest that sex differences in susceptibility to diseases may be caused by genotype differences in detoxifying enzymes such as glutathione S-transferase. The data obtained may prove to be useful for epidemiological studies.