Identifying gene variants underlying the pathogenesis of diabetic retinopathy based on integrated genomic and transcriptomic analysis of clinical extreme phenotypes

Advances in molecular epidemiology of diabetic retinopathy: from genomics to gut microbiomics

Diabetic retinopathy (DR) remains a prevalent complication of diabetes mellitus and a leading cause of blindness worldwide. The growing global diabetic population underscores the urgency to deepen our understanding of DR pathogenesis and develop effective prevention strategies. This review synthesizes recent advancements in molecular epidemiology, spanning genomics, epigenomics, transcriptomics, proteomics, metabolomics, and gut microbiomics, elucidating genetic underpinnings, epigenetic modifications, transcriptional alterations, protein biomarkers, metabolic disruptions, and gut microbiota dysbiosis associated with DR. Highlighted are key findings from genome-wide association studies (GWAS), Mendelian randomization (MR) studies, candidate gene association studies, and advancements in epigenetic mechanisms, revealing intricate disease pathways and potential therapeutic targets. Additionally, insights into altered metabolic profiles and gut microbiota compositions in DR underscore their emerging roles in disease progression and complications. Challenges and future directions in molecular epidemiological research are discussed to accelerate the translation of these findings into clinical applications for personalized DR management. The integration of multi-omics research findings may provide novel perspectives for facilitating rapid and accurate disease diagnosis, enabling dynamic disease monitoring, and advancing targeted therapeutic strategies.

Identification of Genetic Variants for Diabetic Retinopathy Risk Applying Exome Sequencing in Extreme Phenotypes

Background

Diabetic retinopathy (DR) risk has been shown to vary depending on ethnic backgrounds, and thus, it is worthy that underrepresented populations are analyzed for the potential identification of DR-associated genetic variants. We conducted a case-control study for the identification of DR-risk variants in Mexican population.

Methods

We ascertained 60 type 2 diabetes mellitus (T2DM) patients. Cases (n = 30) were patients with advanced proliferative DR (PDR) with less than 15 years after a T2DM diagnosis while controls (n = 30) were patients with no DR 15 years after the diagnosis of T2DM. Exome sequencing was performed in all patients, and the frequency of rare variants was compared. In addition, the frequency of variants occurring in a set of 169 DR-associated genes were compared.

Results

Statistically significant differences were identified for rare missense and splice variants and for rare splice variants occurring more than once in either group. A strong statistical difference was observed when the number of rare missense variants with an aggregated prediction of pathogenicity and occurring more than once in either group was compared (p = 0.0035). Moreover, 8 variants identified more than once in either group, occurring in previously identified DR-associated genes were recognized. The p.Pro234Ser KIR2DS4 variant showed a strong protective effect (OR = 0.04 [0.001-0.36]; p = 0.04).

Conclusions

Our study showed an enrichment of rare splice acceptor/donor variants in patients with PDR and identified a potential protective variant in KIR2DS4. Although statistical significance was not reached, our results support the replication of 8 previously identified DR-associated genes.