IGF-1 gene polymorphisms (rs35767, rs6218, rs6212, rs972936, and rs6214) and the progression of diabetic retinopathy (DR) in Iraqi patients

Abstract

The present study investigated the association between IGF-1 gene polymorphisms (rs35767, rs6218, rs6212, rs972936, and rs6214) and the development and progression of diabetic retinopathy (DR) in Iraqi patients. A total of 90 male participants were enrolled, including 30 healthy controls and 60 patients with type 2 diabetes mellitus (T2DM), who were further divided into 30 patients with DR and 30 without DR, Small sample size and the study's limitation to males. Blood samples were collected after obtaining informed consent, with EDTA tubes used for HbA1c measurement and molecular analysis and gel tubes for biochemical assays. The mean age was 48 years in the control group and 51 years in the patient group. The study was conducted over a 10-month period (December 2023-September 2024) at Al-Nahrain Eye Specialty Center, Ramadi, Iraq. The analysis of IGF-1 gene polymorphisms revealed significant genotype differences among the DR, DNR, and control groups. For rs35767, the GG genotype was significantly associated with DR compared with both the DM (P = 0.0127) and control groups (P = 0.0325), while the AA genotype showed a significantly lower frequency in the DR group than in controls (P = 0.0305). The rs972936 polymorphism was also associated with DR, with the TC genotype showing significant differences between DR and DM (P = 0.0073) and DR and controls (P = 0.0027), whereas the TT genotype differed significantly between DR and DM (P = 0.0389). In contrast, no significant associations were observed for rs6212, rs6218, or rs6214. Haplotype analysis demonstrated that AAATC was significantly more frequent in the DR group (88%) than in the DM and control groups (60%; P = 0.03), whereas AAACC was absent in DR and detected only in the DM and control groups (P = 0.045). Although the AAATT haplotype exhibited the lowest mean IGF-1 level (126.47), IGF-1 concentrations did not differ significantly among haplotypes (P = 0.8254). It is worth noting that patients suffering from secondary complications of diabetes such as neuropathy and nephropathywere excluded, as were female participants.