MTHFR and ischemic stroke: Folic acid treatment in the MPV(Q1–2) and the MTHFR 677 CC/CT genotype subgroup reduced ischemic stroke risk by 44% (HR: 0.56; 95% CI: 0.33–0.95; p = 0.032) and 49% (HR: 0.51; 95% CI: 0.30–0.85; p = 0.010), but the other subgroups were not significant.