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 ratio and 95% confidence intervals. RESULTS: Associations were found with the Duffy Fya+ group, which is more frequent in white than black populations. In Mantel-Haenszel analyses, OAG was positively associated with Duffy Fya+ 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 Fya+ and male gender, P = .01; interaction of Duffy Fya+ and intraocular pressure, P = .04). No associations between OAG and the ABO or Rh blood groups were seen. CONCLUSIONS: The associations with Duffy Fya+, 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.