MTR (5-Methyltetrahydrofolate-Homocysteine Methyltransferase): MTR is a critical enzyme involved in the remethylation pathway of homocysteine metabolism. This enzyme catalyzes the transfer of a methyl group from 5-methyltetrahydrofolate (5-MTHF) to homocysteine, generating methionine and tetrahydrofolate (THF). Methionine serves as a precursor for S-adenosylmethionine (SAM), a universal methyl donor essential for various methylation reactions in the body, including DNA methylation, neurotransmitter synthesis, and histone modification. The remethylation of homocysteine by MTR is a vital process for maintaining normal homocysteine levels and ensuring an adequate supply of methyl groups for cellular methylation reactions. Dysregulation of MTR activity, often due to genetic mutations or deficiencies...