Prevalence of the methylenetetrahydrofolate reductase 677C > T mutation in the Mediterranean Spanish population. Association with cardiovascular risk factors.

Methylenetetrahydrofolate reductase (MT-HFR) is a key enzyme involved in folate metabolism. A common cytosine (C) to a thymine (T) mutation at nucleotide 677 (677C > T) in the MTHFR gene which converts an alanine residue to a valine, has been related with several biochemical phenotypes and with cardiovascular risk, depending on the population studied. Our objective was to estimate the prevalence of the 677C > T mutation in a large and randomly selected sample (289 men and 427 women) from the Mediterranean Spanish population, and to test the association between this genetic variant and some cardiovascular risk factors. For both genders, the prevalence of CC, CT and TT subjects was 32.0, 52.2 and 15.8%, respectively. The frequency (95% confidence interval) of the 677T allele was 0.44 (0.40-0.48) in men and 0.40 (0.37-0.44) in women. This prevalence was significantly different from other European countries, and among the highest reported in the world for any healthy population. We found no association between the 677C > T gene variants and age, body mass index (BMI), total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides or diastolic blood pressure in men and women. However, in men, a statistically significant increase of systolic blood pressure with the number of mutant alleles was found (122.2 mmHg in CC, 125.1 mmHg in CT and 128.5 mmHg in TT subjects; p for trend = 0.030). This association remained significant (p = 0.047) even after adjustment for age, BMI, alcohol consumption, tobacco smoking, education and physical activity.