rs1800734

Meta-analysis of 24 case-control studies examining associations between MLH1 gene polymorphisms and colorectal cancer (CRC) risk. The study found that rs63750447 (MLH1 c.1151T>A) was significantly associated with increased CRC risk (OR 2.28-2.29, P<0.001), while rs1800734 (c.-93G>A) and rs1799977 (c.655A>G) showed no significant associations with CRC susceptibility.

This case-control study examined two mismatch repair gene polymorphisms (hMLH1 rs1800734 and hMSH2 rs2303425) in 422 Slovak lung cancer patients and up to 511 controls. The rs1800734 A allele showed decreased lung cancer risk in the dominant model (OR=1.40, p=0.01), particularly in women (OR=2.00, p=0.006), while the rs2303425 CC genotype increased risk in the recessive model (OR=2.28, p=0.024). The combined GGCC genotype showed markedly elevated risk (OR=3.08, p=0.03; OR=11.56 in women, p=0.005).

This study characterized mismatch repair (MMR) system defects in 96 malignant astrocytomas (20 grade II, 19 grade III, 57 grade IV glioblastomas). Loss of MLH1 expression was associated with MLH1 promoter hypermethylation and the MLH1 -93G>A polymorphism (rs1800734). MSH6 loss was associated with longer overall survival in high-grade astrocytomas treated with radiotherapy alone (HR=2.17, 95% CI 1.14-4.11, p=0.015) but not in those treated with radiotherapy plus chemotherapy. Only 5% of tumors were microsatellite-instable, and germline MMR mutations were rare.

This study analyzed mismatch repair (MMR) system defects in 96 malignant astrocytomas by examining MLH1, MSH2, and MSH6 protein expression, promoter methylation, and gene mutations. The MLH1 -93G>A polymorphism (rs1800734) AA genotype was significantly associated with glioblastomas (12% vs 4% in controls, P=0.017) and with MLH1 promoter hypermethylation and loss of expression. Loss of MSH6 expression was associated with poor overall survival in high-grade astrocytoma patients (HR=1.76, 95% CI 1.01-3.07, P=0.045).