Facteurs nutritionnels, homocystéine et polymorphisme C677T du gène de la méthylène tétrahydrofolate réductase dans la population algérienne

Abstract

This descriptive study aimed to examine the relationship between plasma homocysteine (tHcy), vitamin B12, folate and others biochemical metabolic levels as well as polymorphisms of methylenetetrahydrofolate reductase (MTHFR) gene. Methods. A total of 131 patients with cardiovascular diseases were selected. The concentration of tHcy, folic acid and vitamin B12 levels were determined using a competitive immunoassay method. Plasmatic total cholesterol, triglyceride, glucose, creatinine and urea concentrations were measured by the colorimetric method. The genetic analysis of the MTHFR C677T and cystathionine β-synthase (CBS) 844ins68 polymorphisms was performed by PCR. The (MTHFR) C677T mutations were evaluated also in 147 healthy control subjects. Results. Plasma tHcy was significantly higher in the patients with CVD (35.74±10.28 μmol/L). This hyperhomocysteinemia (HHcy) was correlated positively with age, urea and creatinine. An elevated plasma tHcy and glucose level was also found in patients with arterial hypertension (AHT). The frequency of the TT genotype was 16.1% in the patient group compared with 14.3 % in the healthy controls. The CT genotype constituted 40.1% and 43.5% in the control group and the patients group respectively. There was no significant difference in the occurrence of the TT genotype between the studied groups. The MTHFR and CBS mutations does not seem to be associated with either high tHcy or the occurrence of cardiovascular diseases in the studied patients and this lack of correlation could be explained by the level of folatemia which seem must to be lower than in our study. CVD patients with 677CT/TT genotypes had a higher concentration of total cholesterol (T Chol) than those with 677CC genotype. Besides, the presence of 677T variant conjugated with hypofolatemia (≤16 ng/mL) had a more detrimental effect on the level of T Chol. Folatemia and vitamin B12 were much higher in 677CC genotype compared to 677CT/TT genotype in CVD subjects without hyperlipidemia (p<0.05), however in patients with hyperlipidemia these values became lower also with 677CC genotype. Conclusion. HHcy aggravate in patients with AHT and hypercreatinemia. The effect of 677CT/TT variants on T Chol, folate and vitamin B12 can be explained by a direct alteration of these metabolites by mutation and in part by an adverse effect of HHcy on lipid profiles and on plasmatic folate and vitamin B12.