Kaidonis, G.Abhary, S.Daniell, M.Gillies, M.Fogarty, R.Petrovsky, N.Jenkins, A.Essex, R.Chang, J.Pal, B.Hewitt, A.Burdon, K.Craig, J.2015-09-062015-09-062014Clinical and Experimental Ophthalmology, 2014; 42(5):486-4931442-64041442-9071http://hdl.handle.net/2440/94118BACKGROUND: Diabetic retinopathy (DR) is a blinding disease of increasing prevalence that is caused by a complex interplay of genetic and environmental factors. Here we describe the patient recruitment methodology, case and control definitions, and clinical characteristics of a study sample to be used for genome-wide association analysis to detect genetic risk variants of DR. METHODS: One thousand six hundred sixty-nine participants with either type 1 (T1) or type 2 (T2) diabetes mellitus (DM) aged 18 to 95 years were recruited in Australian hospital clinics. Individuals with T2DM had disease duration of at least 5 years and were taking oral hypoglycaemic medication, and/or insulin therapy. Participants underwent ophthalmic examination. Medical history and biochemistry results were collected. Venous blood was obtained for genetic analysis. RESULTS: Six hundred eighty-three diabetic cases (178 T1DM and 505 T2DM participants) with sight-threatening DR, defined as severe non-proliferative DR, proliferative DR or diabetic macular oedema were included in this analysis. Eight hundred twelve individuals with DM but no DR or minimal non-proliferative DR were recruited as controls (191 with T1DM and 621 with T2DM). The presence of sight-threatening DR was significantly correlated with DM duration, hypertension, nephropathy, neuropathy, HbA1C and body mass index. Diabetic macular oedema was associated with T2DM (P < 0.001), whereas proliferative DR was associated with T1DM (P < 0.001). CONCLUSIONS: Adoption of a case-control study design involving extremes of the DR phenotype makes this a suitable cohort, for a well-powered genome-wide association study to detect genetic risk variants for DR.en© 2013 Royal Australian and New Zealand College of Ophthalmologistsdiabetic macular oedema; diabetic retinopathy; genome-wide association studyJournal article003002225110.1111/ceo.12239000339952400013156870