Open-angle glaucoma and blood groups: The Barbados Eye Study

Objective: To evaluate the association of open-angle glaucoma (OAG) with ABO, Rh and Duffy blood groups in the population-based Barbados Eye Study. Design: Case-control study. Setting and Participants: A subset of black Barbados Eye Study participants, which included 199 OAG cases and 1063 controls. Data Collection: ABO, Rh and Duffy blood groups were determined as part of a comprehensive study visit, which included assessment for OAG through perimetry, fundus photography, and ophthalmologic examination. Outcome Measures: Comparison of blood groups between OAG cases and nonOAG controls, expressed as odds ratios and 95% confidence intervals. Results: Associations were found with the Duffy Fy^a+ group, which is more frequent in white than black populations. In Mantel-Haenszel analyses, OAG was positively associated with Duffy Fy^a+ in men (odds ratio, 2.67; confidence interval, 1.52 to 4.69) and in persons with intraocular pressure more than 21 mm Hg (odds ratio, 3.32; confidence interval, 1.49 to 7.38). Logistic regression analyses confirmed these findings (interaction of Duffy Fy^a+ and male gender, P=.01; interaction of Duffy Fy^a+ and intraocular pressure, P=.04). No associations between OAG and the ABO or Rh blood groups were seen. Conclusions: The associations with Duffy Fy^a+, which had not been reported previously in a black population, support the involvement of genetic factors in OAG. However, the lack of association between OAG and blood group markers of African ancestry is inconsistent with a genetic explanation for the differences in OAG prevalence between blacks and whites. Our findings suggest gene-environment interactions in OAG, to be explored by further studies of OAG and Fy markers by racial group and gender.