Methylenetetrahydrofolate Reductase C677T Gene Variant in Relation to Body Mass Index and Folate Concentration in a Polish Population

Background: Methylenetetrahydrofolate reductase (MTHFR) is an enzyme responsible for producing an active form of folate. The MTHFR T677T genotype may have adverse health effects associated with weight gain and a reduction in folate availability. Aim: In this study, we examined the influence of the MTHFR C677T variant on BMI and determined its role as a risk factor for obesity. We also assessed the relationships between the MTHFR C677T genotype and folate and vitamin B(12) concentrations in subjects before and after radical weight loss. Methods: The study group consisted of 1712 Caucasian adults of Polish nationality with a wide range of body mass indexes (BMIs). DNA was extracted from the blood, and the C677T variant was tested with RFLP-PCR and real-time-PCR. Results: There was no significant influence found for the MTHFR 677 TT genotype on BMI or the obesity risk in codominant, dominant or recessive inheritance models. Individuals with obesity and the TT genotype had significantly lower folate concentrations. After radical weight reduction, the impact of the risk genotype, as well as homeostasis between folate and vitamin B(12) in TT homozygotes, seems to be attenuated. Conclusion: Although the MTHFR 677TT genotype is not directly related to a higher BMI in Polish adults, it has a detrimental effect on folate concentrations in individuals with high BMI values.