GENETIC RISK-FACTORS IN DIABETIC-RETINOPATHY

Diabetic retinopathy is the leading cause of blindness in adults aged 30 to 65 years. However, 20% of the diabetic population does not devel op significant retinopathy. To examine the influence of immune-related genetic factors on the development of diabetic retinopathy, we studie d immunoglobulin allotypes in 102 subjects aged 8 to 20 years, who had had Type 1 (insulin-dependent) diabetes mellitus for 4.5 to 11 years (mean 7.3 years). HLA had been previously typed on 59 of these subject s. Retinopathy was assessed by expert review of retinal photographs. A mong the 44 patients who had evidence of retinopathy, 33(75%) were G2 m(23+), while among the 58 patients without retinopathy but with simil ar duration of disease, only 28(48%) were G2 m(23+) (p = 0.006). The H LA-DR types of patients with and without retinopathy were not signific antly different. We conclude that there is significant evidence of an association between G2m(23) at the locus encoding IgG2 subclass heavy chains and susceptibility to the development of diabetic retinopathy e arly in the clinical course of the disease. Our findings provide impor tant independent confirmation of a previous report of association betw een Gm allotypes and predisposition to diabetic retinopathy. We are un able to determine if the Gm effect on development of retinopathy is du e to the G2 m(23) allotype itself, or due to genes that are closely li nked to, and in linkage disequilibrium with, the locus encoding the G2 m(23) allotype.