Replication of genetic loci implicated in diabetic retinopathy

Recent genome-wide association studies for diabetic retinopathy (DR) have identified novel single nucleotide polymorphisms (SNPs) associated with this potentially blinding disease. These markers could prove useful in risk profiling, if the association are validated by replication. To date, these associations have not been well assessed in independent cohorts. The objective of this study was to ascertain any association of these polymorphisms with advanced stages of DR.

A total of 463 patients who had either type 1 (n = 46) or 2 (n = 417) diabetes were genotyped for 24 SNPs previously implicated in DR. Cases (n = 163) were defined as people with severe nonproliferative DR or proliferative DR. Control participants (n = 300) with a confirmed duration of diabetes of at least 5 years had either no evidence of DR or only mild DR.

Two SNPs (rs1073203 and rs4838605) were found to be significantly associated with DR in patients with diabetes after adjusting for covariants; rs1073203-G (P = 0.012, odds ratio [OR] = 0.317, 95% confidence interval [95% CI]: 0.129-0.778), rs1073203 in a dominant model (P = 0.005, OR = 0.251, 95% CI: 0.096-0.655), rs4838605 in an additive model (P = 0.047, OR = 1.650, 95% CI: 1.007-2.703), In a dominant model rs1073203 (P = 0.027, OR = 1.400, 95% CI: 0.101-0.857), was significantly associated with DR in type 2 diabetes after adjustment for covariants. This study was sufficiently powered to replicate previous findings.

This study confirmed that two variants (rs1073203 and rs4838605) are associated with advanced stages of DR in our cohort. The underlying genes in these candidate regions provide interesting future gene association targets for understanding the pathogenesis of DR.