Importance of the determination of homocysteine and C667T polimorphism of methylenetetrahydrofolate reductase

Hyperhomocysteinemia (HHcy) is an independent risk factor for atherothrombotic diseases. Folic acid, vitamin B-12 and the enzyme methylenetetrahydrofolate reductase (MTHFR) are some of the components involved in homocysteine (Hcy) metabolism. The aim of the present study was to evaluate the clinical usefulness of homocysteinemia determination and the C677T polymorphism analysis of the MTHFR. Homocysteine (ELISA); folic acid and vitamin B-12 levels (chemiluminescence) and C677T polymorphism of the MTHFR (PCR-RFLP) were evaluated in 112 healthy subjects. Twenty-five per cent of the population showed hyperhomocysteinemia (Hcy > 15 mu M). Hcy levels in subjects with folate or B-12 deficiency were significantly higher than those found in non deficient individuals (mean: 15.8 mu M or 15.6 mu M vs 12.5 mu M). Homozygote subjects (TT) showed higher Hcy levels than heterozygote and normal individuals (14.5 mu M, 13.3 mu M and 12.5 mu M, respectively). Forty per cent of the B-12 deficient subjects, fifty-four per cent of the folate deficient individuals, forty-three per cent of the MTHFR-TT subjects and a hundred per cent of the MTHFR-TT individuals with B12 deficiency turned out to be hyperhomocysteinemic. Therefore, homocysteinemia determination could evidence the presence of an atherothrombotic risk factor and likely vitamin deficiencies. Moreover, MTHFR polymorphism determination makes it possible to detect an important genetic factor of hyperhomocysteinemia.