Genetic variation around the collagen IV gene locus and proliferative retinopathy in type 2 diabetes mellitus

The development of proliferative retinopathy in type 2 diabetes mellitus may be under genetic control. A well-documented pathological change in the fundal capillaries of patients with diabetic retinopathy is basement membrane thickening, with an increased amount of collagen IV protein. Variation at the collagen 1a IV gene therefore may explain familial susceptibility to this complication. It has been previously reported that genetic variation at the collagen 1a locus, as shown by allelic association with a HindIII restriction site, predisposes to diabetic nephropathy where basement membrane thickening is also prevalent. In order to test the hypothesis that the collagen 1a IV gene locus is important in the development of diabetic retinopathy, a population association study was performed comparing allele frequencies of the HindIII RFLP in diabetic patients with retinopathy and controls. No statistically significant differences were found between allele frequencies or genotypes in the two groups. The future use of similar studies in diabetic retinopathy is discussed.