Association of MTHFR C677T, MTHFRA1298C, and MTRRA66G Gene Polymorphisms with Hyperhomocysteinemia and Its Modulation by the Combined Effect of Vitamin B12 and Folate in Chinese Population with Hypertension.

Background: In China, the MTHFR 677T allele, unlike in most Western populations, is a rare genetic variant linked to various disorders. The contributing nutritional and genetic factors to this genetic risk remain unclear.

Objective: This study aimed to elucidate the interactions between genetic variations in total homocysteine (tHcy) pathway genes, serum tHcy concentrations, and nutritional factors in a Chinese population with hypertension.

Methods: This study analyzed 1304 Chinese adults with hypertension aged ≥18 y enrolled in the China Precision Nutrition and Health KAP Real World Study (CPNAS). Serum concentrations of vitamin B12 and folate were measured using the magnetic microparticle chemiluminescence method, and tHcy concentrations were measured using Hcy Assay kits. Identification of the MTHFR C677T, MTHFR A1298C, and MTRR A66G polymorphisms was performed via time-of-flight nucleic spectrometry.

Results: Our findings revealed significant sex differences in tHcy concentrations, with males exhibiting higher tHcy concentrations than females (13.95 μmol/L vs. 11.15 μmol/L, P < 0.001). Individuals deficient in both vitamin B12 and folate had an increased risk of hyperhomocysteinemia (H-Hcy) (57.4%). In contrast, the prevalence of H-Hcy was lower among those deficient in either vitamin B12 (31.1%) or folate (23.2%) alone. Significant associations were identified between the MTHFR C677T and A1298C polymorphisms and elevated serum tHcy concentrations, particularly in individuals homozygous for the T allele. Conversely, the MTRR A66G genotype did not show a significant correlation with tHcy concentrations. Optimal vitamin B12 concentrations significantly modulated the genotypic effect on tHcy concentrations, with individuals having adequate vitamin B12 and folate exhibiting low tHcy concentrations, even among high-risk genotypes (TT).

Conclusions: Adequate concentrations of folate and vitamin B12 significantly reduce serum tHcy concentrations and mitigate the genotypic impact on tHcy concentrations, highlighting the potential for targeted nutritional interventions to manage cardiovascular risks associated with H-Hcy. This trial was registered at clinicaltrials.gov as ChiCTR2100051983.