Association of DCC, MLH1, GSTT1, GSTM1, and TP53 gene polymorphisms with colorectal cancer in Kazakhstan

Abstract

This study presents the first results of a moleculargenetic study of colorectal cancer (CRC) in Kazakhstan. Blood samples were collected from patients diagnosed with rectal or colon cancer (249 individuals) as well as a control cohort of healthy volunteers (245 individuals), taking into account the age, gender, ethnicity, and smoking habits of the CRC patients. Combined analysis of data obtained from individuals of either Kazakh or Russian decent showed a significant association with increased CRC risk in the following genotypes: DCC (32008376G/G and G/A versus A/A; OR= 3.45, 95 % confidence interval (95 %CI)=1.75–6.81, χ2 = 14.07, p<0.0002), MLH1 (-93G/G versus G/A and A/A; OR=1.45, 95 %CI=1.02–2.07, χ2 =4.21, p<0.04), TP53 (Pro72Pro; OR=3.80, 95 %CI=2.46–5.88, χ2 =61.27, p<0.0001), combination GSTT1 deletions with heterozygotes versus normal homozygotes (OR=1.43, 95 %CI=1.00–2.04, χ2 =3.90, p<0.05), and GSTM1 deletions (OR=1.83, 95 %CI=1.28–2.63, χ2 =11.04, p<.001). Analysis for ethnicity and smoking for each of the investigated polymorphisms showed that some genotypes can have a predictive value for susceptibility to CRC, at least those that demonstrate statistically significant ORs either for the combined mixed population of Kazakhstan or for both main ethnic groups separately (Kazakhs and Russians): TP53 Pro72Pro homozygous (for Kazakh—OR=3.40, 95 %CI=1.63–7.06, χ2 = 11.35, p<0.003; for Russian—OR=4.69, 95 %CI=2.53– 8.66, χ2 =53.19, p<0.0001) and GSTM1 deletions (for Kazakh—OR=2.30, 95 %CI=1.21–4.40, χ2 =8.42, p<0.01; for Russian—OR=1.64, 95 %CI=1.01–2.66, χ2 =7.82, p<0.02).