MTHFR and migraine disorder: Of the 50 variables tested and after Bonferroni correction for multiple testing, migraine diagnosis (P < 0.0001, degree of freedom (df) = 2), unilateral head pain (P = 0.002, df = 2), physical activity discomforts (P < 0.001, df = 2) and stress as a migraine trigger (P = 0.002, df = 2) were all factors that were significantly associated with MTHFR genotype (Table 2).