Mismatch Repair Gene MLH3 Pro844Leu and Thr942Ile Polymorphisms and the Susceptibility to Cervical Carcinoma and HPV Infection: A Case-Control Study in a Chinese Population

To investigate the association between MLH3 Pro844Leu, Thr942Ile polymorphisms and potential linkage with the risk of cervical carcinoma and potential effect on protein function, we carried out a case-control study with 400 cervical squamous cell carcinoma, 400 CIN3 and 1200 normal controls in a Chinese population. The results showed that there was an increased risk of cervical carcinoma and CIN3 associated with the genotype 844CT [OR 2.17 (1.61-2.94); P<0.001; OR 1.49 (1.08-2.07), P 0.017, respectively] and a decreased risk with the 942CT genotype [OR 0.56 (0.38-0.82); P<0.001; OR 0.37 (0.24-0.58), P<0.001, respectively]. Most 844CT genotypes were linkage CT(844)-CC(942), which increased the risk of cervical carcinoma and CIN3 [77/83, OR 2.04 (1.48-2.80), P<0.001; 55/61, OR 1.46 (1.03-2.06), P 0.035, respectively]. Most 942CT were linkage CC(844)-CT(942), which decreased the risk of cervical carcinoma [29/35, OR 0.60 (0.40-0.91); P 0.017; 18/24, OR 0.33 (0.20-0.55), P<0.001, respectively]. In some grouping, the 844CT and 942CT were further enriched; especially HR-HPV-positive subjects both in the CIN3 and the cervical carcinoma, the 844CT had greater enrichment. These results included that CT(844)-CC(942) was associated with a high risk of cervical carcinoma and CIN3, and the CC(844)-CT(942) decreased the risk. The 844CT had a higher level of enrichment in HR-HPV positive individuals, which is probably related to HR-HPV susceptibility. There was no significant difference of the MLH3 mRNA expression and these two amino acid substitutions did not impact on the protein function.