ABO blood group distribution in migraine patients; the relationship of phenotypes with migraine subtypes, clinical features, and white matter lesions: A Retrospective Case-Control Study

Background Migraine is a common and disabling neurological disorder with a complex and multifactorial pathophysiology. While genetic and vascular mechanisms have been extensively studied, the potential role of the ABO blood group system in migraine susceptibility and clinical characteristics remains unclear. This study aimed to evaluate the distribution of ABO and Rh blood groups in patients with migraine and to investigate their associations with migraine subtypes, clinical features, and white matter lesions (WMLs). Methods This retrospective case–control study included 411 migraine patients aged 18–50 years and 4319 control individuals from the same geographical region. Migraine diagnosis and classification were established according to the International Classification of Headache Disorders, 3rd edition. ABO and Rh blood groups were determined using the gel centrifugation method. Migraine subtypes, clinical characteristics, and the presence of WMLs on cranial magnetic resonance imaging were recorded. Group comparisons and univariate logistic regression analyses were performed. Results Blood group B was significantly less frequent in migraine patients compared with controls (13.4% vs. 18.6%, p = 0.009). In univariate logistic regression analysis, blood group B was associated with lower odds of migraine (OR = 0.67, 95% CI: 0.503–0.906). No significant differences were observed between migraine patients and controls with respect to A, O, and AB blood groups or Rh status. ABO and Rh blood group distributions were not significantly associated with migraine subtypes, the presence of WMLs, headache duration, or monthly headache frequency. Conclusions Blood group B was underrepresented among migraine patients compared with the healthy population from the same geographical region. No associations were identified between ABO or Rh blood groups and migraine subtypes, clinical headache characteristics, or white matter lesions. These findings should be considered hypothesis-generating and require confirmation in larger, multicenter studies.