Abstract
Aim: to analyze the impact of single nucleotide polymorphisms in the genes encoding methylenetetrahydrofolate reductase, methionine synthase, betaine-homocysteine S-methyltransferase, and cystathionine beta-synthase on homocysteine levels and stroke risk using a systematic review of the English-language literature from 1993 to 2025. Materials and methods. The literature review was conducted in accordance with the PRISMA 2020 guidelines for systematic reviews. Information sources and search strategy: search for sources of English-language literature for the period 01.01.1993 - 22.07.2025 using the keywords methylenetetrahydrofolate reductase, MTHFR, methionine synthase, MS, betaine-homocysteine S-methyltransfarase, BHMT, cystathionine beta synthase, CBS, SNP, homocysteine, stroke, rs1801133, rs1801131, rs1805087, rs3733890, rs5742905, rs2851391, rs234713, rs 11701048, rs 9982015, rs 234709, rs6586282 and 844ins68 using the medical scientific database Pubmed. Results. The SNP rs1801133 of the MTHFR gene causes elevated homocysteine levels and is associated with cardiovascular disease. The 677T allele of the SNP rs1801133 is a risk factor for ischemic stroke, coronary heart disease, and hyperhomocysteinemia, with homocysteine levels in 677TT homozygotes significantly higher than those in 677CT and 677CC genotypes, including healthy individuals. Minor monozygotes of 677TT had a significantly higher risk of ischemic stroke and coronary heart disease compared with 677CC genotype carriers. The association between the SNPs rs1801131 MTHFR, SNP rs1805087 encoding MS, homocysteine levels, and stroke risk is more controversial. SNP rs3733890 of the gene encoding BHMT is associated with hyperhomocysteinemia. Among the SNPs of the gene encoding CBS, there are those that increase or decrease the level of homocysteine, some studies deny such an effect. Conclusion. According to the literature, the role of SNP rs1801133 of the gene encoding MTHFR in the occurrence of hyperhomocysteinemia can be considered proven, there is a correlation with the risk of stroke and some other diseases of the cardiovascular system. In the English-language scientific literature there is no data on the influence of SNPs of the genes encoding MTHFR, MS, BHMT and CBS on the level of homocysteine and the risk of stroke in the Ukrainian population