Evaluation of the association between the MTHFR C677T polymorphism and clinical characteristics indicated that people who suffered from hypertension had an increased risk for BC (OR = 2.27; 95% CI: 1.08–4.6; P = 0.0264), especially TNBC (OR = 215.38; 95% CI: 2.45–84430.3; P = 0.0317). The gene discussed is MTHFR; the disease is breast cancer.