No Association of Methylenetetrahydrofolate Reductase (MTHFR) C 677T Polymorphism in Susceptibility to Gallbladder Cancer Anvesha Srivastava, 1 Sachchida N. Pandey, 1 P. Pandey, 1 Gourdas Choudhuri, 2 and Balraj Mittal 1 Gallbladder carcinoma (GBC) is a leading cause of cancer deaths in north India. Evidence has highlighted the role of abnormal DNA methylation patterns on inappropriate gene expression in development and progression of various cancers. 5,10-Methylenetetrahydrofolate reductase (MTHFR) plays a major role in provision of methyl groups for DNA methylation. A C=T substitution in MTHFR at nucleotide 677 results in replacement of ala222-to- val in the N-terminal catalytic domain of protein, and causes considerable decrease in enzymatic activity. Thus, MTHFR C677T polymorphism may influence genetic susceptibility to GBC. The present study aimed to examine the role of C677T MTHFR polymorphism in conferring genetic susceptibility to GBC. The present study included 146 proven GBC patients and 210 healthy controls. Genotyping was done by PCR-RFLP method. The MTHFR C677T genotypes in control population were in Hardy-Weinberg equilibrium ( p ¼ ns). No statistically significant difference was observed in frequency of variant TT genotype in GBC patients in comparison to healthy controls (4.1% and 2.9%). Stratification of GBC patients on the basis of presence or absence of gallstones showed no significant association with the disease. Further, gender and age of onset of the disease did not show any significant association. In conclusion, the present study indicates that the genetic risk for GBC is not modulated by MTHFR C677T polymorphism. Introduction G allbladder carcinoma (GBC) is the most common malignant lesion of the biliary tract and fifth most com- mon malignant neoplasm of the digestive tract. GBC still continues to be a diagnostic and therapeutic challenge, char- acterized by late presentation and dismal outcome. The GBC incidence shows marked regional specificity, and highest incidence rates (7.5=100,000 for men and 23=100,000 for women) are seen in Native American and South Ameri- can populations and in people from north India. In India, GBC incidence is very high in the north (4.5=100,000 for men and 10.1=100,000 for women in Delhi) (Indian Council of Medical Research, 1996; Misra et al., 2003). Such geographic variation may be related to different genetic and environ- mental factors, including dietary patterns. Incidence of GBC also shows marked gender bias and affects females six times more commonly than males (Fraumeni, 1975; Lazcano-Ponce et al., 2001; Misra et al., 2003). Etiology of GBC is still obscure, and associated risk factors identified so far include choleli- thiosis, obesity, reproductive factors, chronic infection, and environmental exposure to specific chemicals (Fraumeni 1975; Kimura et al., 1989; Lazcano-Ponce et al., 2001). The human 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been mapped at chromosomal region 1p36.3 and consists of 11 exons spanning 2.2 kb (cDNA Gen- Bank accession number U09806) (Goyette et al., 1994, 1998). MTHFR (EC 1.5.1.20) is one of the main regulatory enzymes of homocysteine (Hcy) metabolism. MTHFR plays a central role in metabolism of folate, which is essential for DNA syn- thesis, and decreased pool of this nutrient may adversely affect DNA synthesis. Reduction in the activity of MTHFR results in accumulation of 5,10-methylenetetrahydrofolate. This elevation accelerates the methylation of uridylate to thymidylate, which may lead to misincorporation of uracil in DNA, thus contributing to the overall level of DNA dam- age in the cell (Hagmar et al., 1994). Therefore, folate defi- ciency induces chromosomal damage, formation of fragile sites, and micronuclei, often associated with tumorigenesis (Krajinovic et al., 2004). Diminished folate status resulting in uracil misincorporation into DNA may lead not only to chromosomal aberrations but also to DNA repair disrup- tion. Moreover, deficiency of folate has been reported in gen- eral Indian population, which may be an additive dietary factor for high risk of GBC in this population (Yajnik et al., 2006). Departments of 1 Genetics and 2 Gastroenterolgy, Sanjay Gandhi Post Graduate Institute of Medical Sciences (SGPGIMS), Lucknow, India. DNA AND CELL BIOLOGY Volume 27, Number 3, 2008 ª Mary Ann Liebert, Inc. Pp. 127–132 DOI: 10.1089=dna.2007.0679 127