MTHFR and metabolic dysfunction-associated steatotic liver disease: Wang et al. (2018) found that the SNP of the MTHFR rs1801133 and NAFLD had a potential synergistic effect on elevated Hcy levels. Li et al. (2017) found that the plasma Hcy levels of different genotypes of the MTHFR rs1801133 showed the tendency of the TT genotype >CT genotype >CC genotype. They concluded that a possible synergistic effect of the MTHFR rs1801133 SNP on plasma Hcy levels increased the risk of IS. In addition, Rutten-Jacobs et al. demonstrated that MTHFR C677T genotype was associated with CSVD subtype (Rutten-Jacobs et al., 2016).