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:

Genetic polymorphisms predisposing to hyperhomocysteinemia in cardiac transplant patients. Genetic determinants for high homocysteine (Hcy) levels are now well known. We studied several single nucleotide polymorphisms (SNP) in Hcy-regulating genes [ methylenetetrahydrofolate reductase (MTHFR) C677 T and A1298C; methionine synthase (MS) A2756 G; methionine synthase reductase (MTRR) A66 G ] in relation to total plasma Hcy levels, transplant coronary artery disease and thromboembolic episodes in 84 heart transplant patients, and we compared the incidence of these polymorphisms with those in a healthy adult controls. At least one copy of the G allele of the MTRR A66 G SNP was found in a significantly greater proportion of cardiac transplant (CTX) recipients compared with controls (94.0% vs. 79.9% respectively). None of the SNP analyzed were correlated with total Hcy plasma levels or the presence of transplant coronary artery disease. However, MS A2756 G was significantly associated with cobalamin levels (AA genotype: 290 + /- 122 pmol/l; AG: 381 + /- 151 pmol/l and GG: 415 + /- 100 pmol/l), as was MTRR A66 G (AA: 478 + /- 219 pmol/l, AG: 306 + /- 124 pmol/l and GG: 306 + /- 123 pmol/l). MTRR A66 G was also correlated with serum folate. No association was found with thromboembolic events. In conclusion, there was a significant difference in the frequency of the G allele genotype of the MTRR A66 G in CTX patients versus controls. Differences in cobalamin and folate levels with the MTRR A66 G and MS A2756 G polymorphisms were noted. Thus, SNP in Hcy-regulating genes may be important determinants of vitamin metabolism in CTX, raising the question of increased vitamin requirements to minimize increased plasma Hcy in this high-risk group.
[["cobalamin", "INDIRECT-REGULATOR", "MS"], ["cobalamin", "INDIRECT-REGULATOR", "A66 G"], ["cobalamin", "INDIRECT-REGULATOR", "A2756 G"], ["cobalamin", "INDIRECT-REGULATOR", "MTRR"]]