[One novel PMS2 germline mutation in a patient with hereditary non polyposis colorectal cancer]

Hereditary non polyposis colorectal cancer [HNPCC] is an autosomal dominant syndrome. The cancer appears between 40 and 50 years of age. Mutation in mismatch repair genes can lead to this cancer .One of the genes which is involved in this disease is PMS2 gene. Here, we present a case with a novel germline mutation in PMS2 gene. The aim of this report was to examine PMS2 gene and identify novel germline mutations in this gene. A 77-year-old male with diagnosis of colorectal carcinoma was referred for genetic testing. He suffered from a polyp with a diameter of 6.8 cm in hepatic flexure. The patient did not meet Amsterdam Criteria and Bethesda Guidelines, but screening for HNPCC was performed on account of pathological findings. Blood sample was used for identification of mutation and the paraffin embedded block was prepared for MSI analysis. One mutation in PMS2 gene was detected by analysis of the amplicon sequencing. The mutation was a transitional mutation in position 676 which led to transformation of guanine to adenine resulting in substitution of glutamic acid for glycine. Immunohistochemistry confirmed abnormal expression of PMS2 gene and MSI assay showed instability of sequenced amplicons in this gene

Association between polymorphism of MTHFR gene and non-familial colorectal cancer

Colorectal cancer is one of the most common malignancies in worldwide. Because the gene 5, 10-methylene-tetrahydrofolate reductase [MTHFR] plays a key role in methylation, synthesis and repair of DNA, numerous studies have focused on evaluating the correlation between polymorphisms of this gene and sporadic colorectal cancer. This study was carried out to examine the association of MTHFR gene polymorphism, C677T, with non-familial colorectal cancer in an Iranian population. We analyzed peripheral blood samples of 118 cases of colorectal cancer and 189 controls by pyrosequencing method. Controls were subjects who had been referred to our center during the study period and had revealed normal findings on colonoscopy. We found that frequency of CC, CT and TT genotypes among the colorectal cancer patients were 51.7%, 28% and 20.3% respectively. The figures for controls were 47.1%, 27% and 25.9% respectively. Furthermore, allele frequency T in the cases was 34% and allele frequency C was 66% while allele frequency T in controls was 39% and allele frequency C was 61%. Interestingly we observed a reverse association between risk of colon cancer with 677TT genotype