Associations between asymmetric dimethylarginine, homocysteine, and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism (rs1801133) in rheumatoid arthritis.

ABSTRACT

OBJECTIVES: The aim of our study was to determine whether asymmetric dimethylarginine (ADMA) levels are associated with homocysteine (Hcy) and methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133) gene variants in patients with rheumatoid arthritis (RA). METHOD: Serum ADMA and Hcy levels were measured in 201 RA individuals [155 (77.1%) females, median age 67 years (interquartile range 59-73)]. The MTHFR C677T polymorphism was assessed by using the LightCyclerTM System. Initially, ADMA was compared across the categories of MTHFR using a one-way analysis of variance (ANOVA), followed by a multivariate model, which accounted for Hcy, age, erythrocyte sedimentation rate (ESR), and homeostatic model assessment (HOMA). RESULTS: In univariable analysis, ADMA differed significantly across the categories of MTHFR (p = 0.037). Patients with the MTHFR 677TT genotype had the highest ADMA levels, with a mean of 0.62 (SE = 0.03), significantly higher than either those patients carrying the MTHFR 677CT (0.55, SE = 0.01) or the MTHFR 677CC (0.55, SE = 0.01) genotype (p = 0.042) in both cases. In the multivariable model, Hcy (p = 0.022) and ESR (p < 0.001) were found to have significant positive associations with ADMA but the relationship between MTHFR gene variants and ADMA was found to be non-significant (p = 0.102). CONCLUSIONS: Hcy and ADMA are significantly associated in RA. It is plausible that abnormal Hcy metabolism plays an important role in premature atherosclerosis in RA by promoting ADMA accumulation and leading to the derangement of vascular haemostasis.