Given an abstract from a research paper, your task is to identify and label relationships between chemical compounds and genes mentioned in the abstract.

The relationship type must be one of ['DOWNREGULATOR', 'SUBSTRATE', 'INDIRECT-REGULATOR', 'PART-OF', 'MODULATOR-ACTIVATOR', 'REGULATOR', 'INHIBITOR', 'COFACTOR', 'UPREGULATOR', 'ACTIVATOR', 'ANTAGONIST', 'NOT', 'INDIRECT-DOWNREGULATOR', 'SUBSTRATE_PRODUCT-OF', 'INDIRECT-UPREGULATOR', 'AGONIST', 'PRODUCT-OF', 'MODULATOR', 'DIRECT-REGULATOR', 'UNDEFINED', 'AGONIST-INHIBITOR', 'AGONIST-ACTIVATOR', 'MODULATOR-INHIBITOR'].

Please format your output as a JSON array. Each entry in the array should express a single relation, formatted as ["<Entity_A>", "<RELATION_A_B>", "<Entity_B>"]. If no relations can be found, please output an empty JSON array [].

Abstract:

Association of MTRRA66 G polymorphism (but not of MTHFR C677 T and A1298C, MTRA2756 G, TCN C776 G) with homocysteine and coronary artery disease in the French population. Methylenetetrahydrofolate reductase polymorphism (MTHFR C677 T) is an established determinant of homocysteine plasma level (t-Hcys) while its association with coronary artery disease (CAD) seems to be more limited. In contrast, the association of the substitutions A2756 G of methionine synthase (MTR), A66 G of methionine synthase reductase (MTRR) and C776 G of transcobalamin (TCN) to both t-Hcys and CAD needs to be evaluated further. The objective was to evaluate the association of these polymorphisms with t-Hcys and CAD in a French population. We investigated the individual and combined effects of these polymorphisms and of vitamin B12 and folates with t-Hcys in 530 CAD patients and 248 matched healthy controls. t-Hcys was higher in the CAD group than in controls (11.8 vs 10.4 microM, P < 0.0001) and in carriers of MTRRAA and MTHFR 677TT than in those carrying the most frequent allele of both polymorphisms (13.8 vs 11.4 microM, P = 0.0102 and 12.5 vs 11.0 mM, P = 0.0065 respectively). The frequency of MTRR A allele was higher in CAD patients than in controls (0.48 [ 95% CI: 0.44-0.52 ] vs 0.38 [ 95% CI: 0.32-0.44 ], P = 0.0081) while no difference was observed for MTHFR 677 T frequency. In multivariate analysis, t-Hcys > median and MTRRAA genotype were two significant independent predictors of CAD with respective odds ratios of 3.1 (95% CI: 1.8-5.1, P < 0.0001) and 4.5 (95% CI: 1.5-13.1, P = 0.0051). In conclusion, in contrast to North Europe studies, MTRRAA genotype is a genetic determinant of moderate hyperhomocysteinemia associated with CAD in a French population without vitamin fortification.
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