Endocrine Abstracts

Background and aims: Diabetic retinopathy (DR) is an important chronic complication of diabetes mellitus (DM), and is the leading cause of new cases of blindness in adults. Although several single nucleotide polymorphisms (SNPs) have been associated with DR, more information is needed to unravel the genetics of this complex disease. MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate expression of at least 60% of all protein-coding genes. A number of miRNAs have been described as having abnormal expressions in patients with DR, including miRNA-126, which regulates endothelial cell response to VEGF, an important pro-angiogenic growth factor involved in DR pathogenesis. Polymorphisms in genes codifying miRNAs (miRSNPs) may alter the expression of the corresponding miRNA and, thus, confer susceptibility for DR. Therefore, miRSNPs in miR-126 gene could be associated with DR susceptibility. Therefore, the aim of this study was to investigate the association between the rs4636297 (G/A) miRSNP in miRNA-126 gene and DR.

Methods: This case-control study comprised 196 type 1 DM (T1DM) patients with DR (cases) and 219 T1DM patients without this complication and with ≥10 years of DM (controls). The rs4636297 miRSNP was genotyped by allele discrimination – real-time PCR technique, using TaqMan MGB probes (Thermo Fisher Scientific).

Results: Genotype distributions of the rs4636297 miRSNP were in Hardy-Weinberg equilibrium in controls. The A allele frequency was 40.0% in cases and 46.0% in controls, and this allele was associated with protection for DR under recessive (OR =0.294, P=0.032), additive (OR =0.087, P=0.001), and dominant (OR =0.348, P<0.001) inheritance models, adjusting for age, presence of hypertension, diabetic renal disease, and cholesterol levels.

Conclusion: Our results suggest for the first time in a Brazilian population, an association between the A of rs4636297 miRSNP in the miR-126 gene and protection for DR.