The Association of Haptoglobin Gene Variants and Retinopathy in Type 2 Diabetic Patients: A Meta-Analysis

AIMS/INTRODUCTION: To collectively evaluate the association between haptoglobin (Hp) gene variants and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM). METHODS: A comprehensive literature review was performed for eligible studies. After inclusion and exclusion selection as well as quality assessment, those studies meeting quality standards were included. In this study, diabetic patients with retinopathy were selected as the case group and those ones without DR were treated as the control group. The recessive model, allele model, additive model, heterozygote model, and homozygote model were utilized to investigate the association of three Hp gene variants and DR. Subgroup analysis on different severity of DR including nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) was also conducted. RESULTS: Six trials from different regions were finally included. A total of 1145 subjects containing 564 T2DM patients with retinopathy were included. The recessive model, allele model, additive model, and homozygote model results showed that Hp gene variants were not associated with DR, NPDR, and PDR. However, the heterozygote model indicated the association of Hp gene variants with DR. CONCLUSIONS: No association was found between the Hp gene variants and PDR and NPDR. More studies are required to verify these findings.