Association between ABO and Rh blood groups and subtypes of age-related macular degeneration: A cross-sectional study

Age-related macular degeneration (AMD) is a leading cause of irreversible visual impairment and is driven by complex genetic, inflammatory, and vascular mechanisms. ABO and Rh blood group antigens, which are expressed on vascular endothelium and involved in immune and hemostatic pathways, have been implicated in various systemic diseases; however, their potential association with AMD phenotypic variation remains unclear. In this cross-sectional study, 488 patients with clinically confirmed AMD from a tertiary referral center were included. AMD was classified as neovascular AMD (wet AMD) or nonneovascular AMD (dry AMD) based on multimodal imaging and standardized diagnostic criteria. ABO and Rh blood group data were obtained from medical records, and individuals with major known AMD risk factors, including smoking, alcohol consumption, and obesity, were excluded to reduce confounding. Associations between AMD subtypes and ABO blood groups and Rh factor were evaluated using the Pearson chi-square test, and crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. The mean age of participants was 66.9 ± 4.7 years, and 273 patients (55.9%) had neovascular AMD. A statistically significant association was observed between ABO blood group distribution and AMD subtypes (χ² = 8.31, p = 0.040). A higher proportion of patients with neovascular AMD had blood group A, whereas blood group B was relatively more common among patients with nonneovascular AMD. However, individual pairwise crude odds ratio analyses did not demonstrate statistically significant associations for specific ABO blood groups. No association was observed for Rh status. These findings suggest a possible modest association between overall ABO blood group distribution and AMD phenotype; however, the clinical significance of this relationship remains uncertain, particularly in the absence of multivariable adjustment. Larger multicenter studies with comprehensive multivariable analyses are warranted.