Association of aldose reductase gene (AKR1B1) polymorphism with diabetic retinopathy

Genetic insights and emerging therapeutics in diabetic retinopathy: from molecular pathways to personalized medicine

Diabetic retinopathy (DR) is a major complication of diabetes worldwide, significantly causing vision loss and blindness in working-age adults, and imposing a substantial socioeconomic burden globally. This review examines the crucial role of genetic factors in the development of DR and highlights the shift toward personalized treatment approaches. Advances in genetic research have identified specific genes and variations involved in angiogenesis, inflammation, and oxidative stress that increase DR susceptibility. Understanding these genetic markers enables early identification of at-risk individuals and the creation of personalized treatment plans. Incorporating these genetic insights, healthcare providers can develop early intervention strategies and tailored treatment plans to improve patient outcomes and minimize side effects. This review emphasizes the transformative potential of integrating genetic information into clinical practice, marking a paradigm shift in DR management and advancing toward a more personalized and effective healthcare model.

Genomic profile of diabetic retinopathy in a north indian cohort

BACKGROUND

Diabetic Retinopathy (DR) is one of the major microvascular complications of diabetes. Being a complex disease, it is important to delineate the genetic and environmental factors that influence the susceptibility to DR in a population. Therefore, the present study was designed to investigate the role of genetic and lifestyle risk factors associated with DR susceptibility in a North-Indian population.

METHODS

A total of 848 subjects were enrolled, comprising of DR cases (n = 414) and healthy controls (n = 434). The Sequenom MassARRAY technology was used to perform target genome analysis of 111 SNPs across 57 candidate genes and 14 intergenic region SNPs that are involved in the metabolic pathways associated with type 2 diabetes (T2D) and DR. Allele, genotype and haplotype frequencies were determined and compared among cases and controls. Logistic regression models were used to determine genotype-phenotype and phenotype-phenotype correlations.

RESULTS

The strongest association was observed with TCF7L2 rs12255372 T allele [p < 0.0001; odds ratio (OR) = 1.81 (1.44-2.27)] and rs11196205 C allele [p < 0.0008; OR = 1.62 (1.32-1.99)]. Genotype-phenotype and phenotype-phenotype correlations were found in the present study.

CONCLUSION

Our study provides strong evidence of association between the TCF7L2 variants and DR susceptibility.

Aberrant expression of AKR1B1 indicates poor prognosis and promotes gastric cancer progression by regulating the AKT-mTOR pathway

Gastric cancer (GC) is a common malignant tumor in the digestive tract and a major cause of global cancer death. Due to the limited access to early screening, many patients are diagnosed with advanced GC. Therefore, postoperative radiotherapy and chemotherapy possess limited efficacy in treating GC. AKR1B1 has been associated with tumorigenesis and metastasis across various tumors, becoming a potential therapeutic target for GC. However, its role and mechanism in GC remain unclear. In this study, AKR1B1 was elevated in GC tissue, depicting a poor prognosis. AKR1B1 is closely related to age, vascular and neural invasion, lymph node metastasis, and the TNM stage of GC. The developed survival prediction model suggested that AKR1B1 expression level is crucial in the prognosis of GC patients. Moreover, the expression level of AKR1B1 in GC tissues is closely associated with the AKT-mTOR pathway. In vitro and in vivo assays functional assays helped determine the oncogenic role of AKR1B1. Additionally, the knockdown of AKR1B1 expression level in GC cell lines could effectively suppress the AKT-mTOR pathway and inhibit the proliferation and migration of tumor cells. In conclusion, this study provides a theoretical basis to establish the potential association and regulatory mechanism of AKR1B1 while offering a new strategy for GC-targeted therapy.

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

Diabetic retinopathy (DR) is a common complication and the leading cause of blindness in patients with type 2 diabetes. DR has been shown to be closely correlated with blood glucose levels and the duration of diabetes. However, the onset and progression of DR also display clinical heterogeneity. We applied whole-exome sequencing and RNA-seq approaches to study the gene mutation and transcription profiles in three groups of diabetic patients with extreme clinical phenotypes in DR onset, timing, and disease progression, aiming to identify genetic variants that may play roles in the pathogenesis of DR. We identified 23 putatively pathogenic genes, and ingenuity pathway analysis of these mutated genes reveals their functional association with glucose metabolism, diabetic complications, neural system activity, and dysregulated immune responses. In addition, ten potentially protective genes were also proposed. These findings shed light on the mechanisms underlying the pathogenesis of DR and may provide potential targets for developing new strategies to combat DR.

Genetic variants of ALR (-106C → T /-12C → G) and serum PKC-δ are associated with peripheral neuropathy in Egyptian diabetic patients with impaired handwriting

Purpose

Diabetic peripheral neuropathy can injure the hand median nerve and cause extensive nerve damage. PKC and ALR are associated with progression of diabetic complications. We hypothesized a genetic association between the ALR polymorphisms (-106C → T/-12C → G) and elevated serum PKC-δ levels in diabetic neuropathy and its adverse effects on handwriting in Egyptian population.

Methods

One hundred DPN were compared with 100 DP and 100 healthy volunteers. ALR -106C → T/-12C → G variants were studied using the PCR-RFLP method. A routine set of standard laboratory markers was determined. Serum PKC-δ concentration was determined by ELISA. Logistic regression analysis and areas under the receiver characteristic curves (AUCs) were evaluated to investigate the predictors of diabetic neuropathy. Arabic handwriting was analyzed based on the recognition of functional features, word shape, and ascending/descending parts of letters.

Results

Individuals carrying ALR-106C → C and -12G → G had a significantly higher risk of developing diabetic neuropathy than individuals with -106C → T and -12C → G genotypes (P = 0.01, P = 0.02). Carriers of the (-106C → T) CC and (-12C → G) GG genotypes had significantly increased serum levels of PKC-δ, FBG, TC, and LDL-c. PKC- δ serum levels were significantly correlated with glycemic and lipid indicators (P < 0.001). PKC-δ is a significant predictor of diabetes with or without neuropathy at a cutoff value of 16.6, sensitivity was 89%, and specificity 100%. All DPN showed complete deterioration of handwriting after the onset of diabetic neuropathy.

Conclusion

The genetic variants ALR-106C → C / -12G → G and PKC-δ in serum may help in the detection and treatment of diabetic neuropathy in Egyptian population before writing performance is affected.

The A allele of the rs759853 single nucleotide polymorphism in the AKR1B1 gene confers risk for diabetic kidney disease in patients with type 2 diabetes from a Brazilian population

OBJECTIVE

The AKR1B1 gene encodes an enzyme that catalyzes the reduction of glucose into sorbitol. Chronic hyperglycemia in patients with diabetes mellitus (DM) leads to increased AKR1B1 affinity for glucose and, consequently, sorbitol accumulation. Elevated sorbitol increases oxidative stress, which is one of the main pathways related to chronic complications of diabetes, including diabetic kidney disease (DKD). Accordingly, some studies have suggested the rs759853 polymorphism in the AKR1B1 gene is associated with DKD; however, findings are still contradictory. The aim was to investigate the association of the rs759853 polymorphism in the AKR1B1 gene and DKD.

METHODS

The sample comprised 695 patients with type 2 DM (T2DM) and DKD (cases) and 310 patients with T2DM of more than 10 years' duration, but no DKD (controls). The polymorphism was genotyped by real-time PCR.

RESULTS

Allelic and genotype frequencies of this polymorphism did not differ significantly between groups. However, the A/A genotype was associated with risk for DKD after adjustment for gender, triglycerides, BMI, presence of hypertension and diabetic retinopathy, and duration of DM, under both recessive (P = 0.048) and additive (P = 0.037) inheritance models.

CONCLUSION

Our data suggest an association between the AKR1B1 rs759853A/A genotype and risk for DKD in Brazilians T2DM patients.

The Influence of Different Types of Diabetes on Vascular Complications

The final outcome of diabetes is chronic complications, of which vascular complications are the most serious, which is the main cause of death for diabetic patients and the direct cause of the increase in the cost of diabetes. Type 1 and type 2 diabetes are the main types of diabetes, and their pathogenesis is completely different. Type 1 diabetes is caused by genetics and immunity to destroy a large number of β cells, and insulin secretion is absolutely insufficient, which is more prone to microvascular complications. Type 2 diabetes is dominated by insulin resistance, leading to atherosclerosis, which is more likely to progress to macrovascular complications. This article explores the pathogenesis of two types of diabetes, analyzes the pathogenesis of different vascular complications, and tries to explain the different trends in the progression of different types of diabetes to vascular complications, in order to better prevent diabetes and its vascular complications.

Exploring the therapeutic mechanisms of Cassia glauca in diabetes mellitus through network pharmacology, molecular docking and molecular dynamics

Cassia glauca is reported as anti-diabetic medicinal plant and is also used as an ethnomedicine. However, its mode of action as an anti-diabetic agent has not been clearly elucidated. Hence, the present study investigated the probable mechanism of action of C. glauca to manage diabetes mellitus via network pharmacology and molecular docking and simulations studies. The reported bioactives from C. glauca were retrieved from an open-source database, i.e. ChEBI, and their targets were predicted using SwissTargetPrediction. The proteins involved in the pathogenesis of diabetes were identified from the therapeutic target database. The targets involved in diabetes were enriched in STRING, and the pathways involved in diabetes were identified concerning the KEGG. Cytoscape was used to construct the network among bioactives, proteins, and probably regulated pathways, which were analyzed based on edge count. Similarly, molecular docking was performed using the Glide module of the Schrodinger suite against majorly targeted proteins with their respective ligands. Additionally, the drug-likeness score and ADMET profile of the individual bioactives were predicted using MolSoft and admetSAR2.0 respectively. The stability of these complexes were further studied via molecular dynamics simulations and binding energy calculations. Twenty-three bio-actives were retrieved from the ChEBI database in which cassiarin B was predicted to modulate the highest number of proteins involved in diabetes mellitus. Similarly, GO analysis identified the PI3K-Akt signaling pathway to be primarily regulated by modulating the highest number of gene. Likewise, aldose reductase (AKR1B1) was majorly targeted via the bioactives of C. glauca. Similarly, docking study revealed methyl-3,5-di-O-caffeoylquinate (docking score -9.209) to possess the highest binding affinity with AKR1B1. Additionally, drug-likeness prediction identified cassiaoccidentalin B to possess the highest drug-likeness score, i.e. 0.84. The molecular dynamics simulations and the MMGBSA indicate high stability and greater binding energy for the methyl-3,5-di-O-caffeoylquinate (ΔG bind = -40.33 ± 6.69 kcal mol-1) with AKR1B1, thus complementing results from other experiments. The study identified cassiarin B, cassiaoccidentalin B, and cinnamtannin A2 as lead hits for the anti-diabetic activity of C. glauca. Further, the PI3K-Akt and AKR1B1 were traced as majorly modulated pathway and target, respectively.

Genetics of Diabetic Retinopathy, a Leading Cause of Irreversible Blindness in the Industrialized World

Diabetic retinopathy (DR) is a chronic complication of diabetes and a leading cause of blindness in the industrialized world. Traditional risk factors, such as glycemic control and duration of diabetes, are unable to explain why some individuals remain protected while others progress to a more severe form of the disease. Differences are also observed in DR heritability as well as the response to anti-vascular endothelial growth factor (VEGF) treatment. This review discusses various aspects of genetics in DR to shed light on DR pathogenesis and treatment. First, we discuss the global burden of DR followed by a discussion on disease pathogenesis as well as the role genetics plays in the prevalence and progression of DR. Subsequently, we provide a review of studies related to DR’s genetic contribution, such as candidate gene studies, linkage studies, and genome-wide association studies (GWAS) as well as other clinical and meta-analysis studies that have identified putative candidate genes. With the advent of newer cutting-edge technologies, identifying the genetic components in DR has played an important role in understanding DR incidence, progression, and response to treatment, thereby developing newer therapeutic targets and therapies.

The relationship between aldose reductase gene C106T polymorphism and the severity of retinopathy in Type 2 diabetic patients: A case-control study

Background:

Hyperglycemia over-activates glucose reduction to sorbitol by aldose reductase (ALR) leading to osmoregulation disruption and cellular damage that cause diabetic complications. We investigated the association of C106T polymorphism of ALR2 gene with the severity of diabetic retinopathy (DR) in Jordanian Type 2 diabetic patients in this case-control study at the Ophthalmology clinic of the National Centre of Diabetes, Endocrinology, and Genetics.

Materials and Methods:

A total of 277 subjects participated in the study (100 diabetics without retinopathy, 82 diabetics with retinopathy, and 95 controls). Blood samples were withdrawn followed by DNA extraction. C106T polymorphism was examined by polymerase chain reaction followed by restriction fragment length polymorphism and gel electrophoresis. Statistical analysis was performed by SPSS software using analysis of variance, multiple logistic regression or Chi-square test.

Results:

The CT and TT genotypes were significantly more prevalent in DR patients than those without DR (CT 50% vs. 38%, TT 16.7% vs. 8%, P = 0.02 and 0.01, respectively). DR patients had T allele more frequently than those without it (41.7% vs. 27%, P = 0.007). Diabetics without retinopathy showed similar genotype and allele frequency to those of nondiabetic controls. No correlation between CT/TT genotypes and the severity of DR in affected subjects was found (χ²: 3.049, P = 0.550).

Conclusion:

C106T polymorphism increased the risk to develop retinopathy in Jordanian Type 2 diabetic patients. T allele of ALR2 was associated with DR. The severity of DR did not show an association with this polymorphism.

Association of Erythropoietin Gene Polymorphisms With Type 2 Diabetic Retinopathy in Adult Patients From Northern India

OBJECTIVES

Our aim in this study was to determine the association of erythropoietin (EPO) gene polymorphisms with diabetic retinopathy in type 2 diabetes patients from northern India.

METHODS

In this case-control study, we recruited 614 participants, consisting of 302 diabetic retinopathy cases and 312 individuals with confirmed type 2 diabetes without retinopathy as controls. EPO polymorphism analysis was performed in all participants using polymerase chain reaction and direct DNA sequence analysis.

RESULTS

The genotype distribution and allele frequency of the c.246+265G>A (rs507392) polymorphism in differed significantly (p<0.05) between the retinopathy and control groups. For the -1306C>A (rs1617640) polymorphism, genotype distribution among the 2 groups analyzed differed significantly (p=0.047), but the distribution of allele frequency was not found to be statistically significant (p=0.07). For the c.∗772G>T (rs551238) variant, genotype distribution did not differ significantly when comparing the 2 groups (p=0.062), but allele frequency distribution did differ significantly (p=0.045). For the polymorphisms analyzed, namely rs507392 and rs1617640, a statistically significant association with retinopathy was observed (dominant model: adjusted odds ratio [OR], 2.23; 95% confidence interval [CI], 1.36 to 3.35; p<0.01; codominant model: adjusted OR, 1.45; 95% CI, 1.00 to 2.09; p=0.048). However, no significant association between c.∗772G>T (rs551238) polymorphism and diabetic retinopathy was found.

CONCLUSIONS

Our findings show 2 polymorphisms (c.246+265G>A [rs507392] and -1306C>A [rs1617640]) in EPO to be risk factors for type 2 diabetic retinopathy in a northern Indian cohort. To our knowledge, this is the first report from India to demonstrate an association between EPO gene polymorphisms and retinopathy.

Sodium-glucose co-transporter 2 inhibitors and diabetic retinopathy: insights into preservation of sight and looking beyond

Sodium-glucose co-transporter 2 Inhibitors (SGLT2i) were initially developed as therapeutic options for patients with type 2 diabetes mellitus (T2DM). Recently, randomized clinical trials have investigated their effects in cardiorenal protection through major adverse cardiovascular event reduction and reductions in diabetic nephropathy. While multiple mechanisms are proposed for this protection, microvascular protection is the primary component of their efficacy. While not primarily emphasized in clinical trials, evidence in other studies suggests that SGLT2i may confer retinoprotective effects via some of the same mechanisms in the aforementioned cardiorenal trials. Diabetic patients are susceptible to vision loss with chronic hyperglycemia promoting inflammation, edema, and retinal pathological changes. Targeting these pathways via SGLT2i may represent opportunities for providers to decrease retinopathy in high-risk T2DM patients, reduce disease progression, and lower drug burden in diabetic retinopathy patients. Further comprehensive clinical trials investigating these associations are needed to establish the potential retinoprotective effects of SGLT2i.

AKR1B1-Induced Epithelial-Mesenchymal Transition Mediated by RAGE-Oxidative Stress in Diabetic Cataract Lens

Purpose: Cataracts are a major cause of visual acuity deterioration in diabetes mellitus (DM) in developed and developing countries. Studies have demonstrated that overproduction of AKR1B1 and receptor for advanced glycation end products (RAGE) plays a major role in the pathogenesis of diabetic cataracts, but it is unclear whether the prevalence of diabetic cataracts is related to epithelial–mesenchymal transition (EMT) in lens epithelial cells. This study aimed to analyze the role of EMT in cataract formation of DM patients. Methods: Immunofluorescence and immunohistochemistry assays were used to estimate AKR1B1, RAGE, AMPK, and EMT levels in epithelial human lens of DM or non-DM cataracts. Results: Immunohistochemical staining demonstrated that pathologic phases and N-cadherin expression levels were significantly higher in epithelial human lens of DM (+) compared to DM (−) cataracts. Immunofluorescent staining showed that AKR1B1 and RAGE were significantly higher in epithelial human lens of DM (+) compared to DM (−) cataracts. Interestingly, acetyl superoxide dismutase 2 (AcSOD2) levels were significantly higher in DM patients’ lens epithelial cells (LECs), whereas AMPKT172 phosphorylation was significantly increased in non-DM patients. This indicates that AMPKT172 might be related to superoxide reduction and diabetic cataract formation. Conclusions: Our results suggest that AKR1B1 overexpression can decrease AMPK activation, thereby increasing AcSOD2 and RAGE-induced EMT in epithelial human lens of DM cataracts. These novel findings suggest that AKR inhibitors may be candidates for the pharmacological prevention of cataracts in patients with DM.

Association between Aldose Reductase Gene C(-106)T Polymorphism and Diabetic Retinopathy: A Systematic Review and Meta-Analysis

Controversial results regarding the associations between aldose reductase (AR) genetic polymorphisms and diabetic retinopathy (DR) have been reported for many years. The present meta-analysis was performed to clarify the effects of the AR gene C(-106)T polymorphism on DR risk. The PubMed, Web of Sciences, Cochrane library, EMBASE, Chinese National Knowledge Infrastructure, and Wan Fang databases were extensively searched in Chinese to select relevant studies with an updated date of April 25, 2018. The Newcastle-Ottawa Scale (NOS) was applied to assess quality. The random-effects model was applied to calculate the pooled OR and 95% CI. This meta-analysis identified 23 studies with an average score of 7.52 for NOS analysis, including 4,313 DR cases and 5,128 diabetes mellitus (DM) control cases. In the overall analysis, a significant association between the AR gene C(-106)T polymorphism and DR susceptibility was found. In subgroups stratified by DM type and ethnicity, significantly increased risks for DR were found in DM type 1, East Asian populations, and Middle Eastern populations. Compared with DR control cases, the following associations were found: T vs. C: OR 0.91, 95% CI 0.85-0.97, I2 = 72.9%; CT + TT vs. CC: OR 0.75, 95% CI 0.68-0.81, I2 = 86.7%; and CT vs. CC: OR 0.86, 95% CI 0.78-0.94, I2 = 70.5%. The results of this meta-analysis showed a significant association between the AR gene C(-106)T polymorphism and susceptibility to DR in DM patients. DM patients with allele T and CT+TT genotype of the AR gene may have a lower risk of DR.

Meta-analysis of the association between aldose reductase gene (CA)n microsatellite variants and risk of diabetic retinopathy

Diabetic retinopathy (DR) is one of the most severe microvascular complications of diabetes mellitus (DM). The (CA)n microsatellite variation of the aldose reductase (ALR) gene has been indicated to be associated with DR in previous studies; however, the results were inconclusive. To provide a more precise evaluation of the association between the (CA)n variations of ALR and the risk for DR, a meta-analysis was performed in the present study. Relevant articles were retrieved from the PubMed, Embase, Chinese National Knowledge Infrastructure and Cochrane Library databases. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the strength of the associations. The present meta-analysis included 17 studies comprising 1,575 DM patients with retinopathy and 1,741 DM patients without retinopathy. The results indicated that the Z-2 allele was a risk factor for DR in Asian (OR=1.82, 95% CI: 1.16-2.86, P=0.009) and Caucasian (OR=2.08, 95% CI: 1.14-3.79, P=0.02) populations, as well as in type 1 diabetes (T1D; OR=3.42, 95% CI: 1.46-8.04, P=0.005) and type 2 diabetes (T2D; OR=1.66, 95% CI: 1.05-2.63, P=0.03). Furthermore, the Z+2 allele was determined to be a protective factor for DR in Caucasian individuals (OR=0.50, 95% CI: 0.34-0.73, P=0.0004) and those with T1D (OR=0.39, 95% CI: 0.27-0.57, P<0.00001). Z+4 was also identified to be a protective factor, reducing the risk of DR in patients with T1D (OR=0.74, 95% CI: 0.57-0.96, P=0.02). Z-4 was revealed to be a risk factor for DR in Asian populations (OR=1.57, 95% CI: 1.22-2.03, P=0.0005) and in individuals with T1D (OR=1.62, 95% CI: 1.27-2.08, P=0.0001). However, no association was detected between the Z, Z+6 and Z-6 alleles and the risk of DR (P>0.05). In conclusion, the present results revealed the following: Z+2 may serve as a protective factor for DR in Caucasian individuals and those with T1D; Z+4 may be a protective factor for DR in patients with T2D; Z-2 may represent a risk factor for DR in all subgroups analyzed; and Z-4 may be a risk factor for DR in Asian populations and patients with T2D.

Aldose Reductase Polymorphisms, Fasting Blood Glucose, and Age-Related Cortical Cataract

Purpose

To determine whether there is an association between polymorphisms of the AKR1B1 gene and cortical cataract in the presence of hyperglycemia.

Methods

In the second cross section of the Blue Mountains Eye Study (BMES), 3508 participants (2334 at 5-year follow-up and 1174 newly recruited participants) were examined during 1997 to 2000. Cataract was graded from lens photographs using the Wisconsin Cataract Grading System. Fasting blood glucose (FBG) was measured. Continuous imputed dosages of minor alleles of 17 AKR1B1 single nucleotide polymorphisms (SNPs) were assessed for associations with prevalent cortical cataract. Gene-environment interactions between SNPs and FBG were examined. Odds ratios (OR) and 95% confidence intervals (CI) for prevalent cortical cataract were estimated using logistic regression adjusting for age, sex, smoking, hypertension, education, and myopia. A P value of 0.005 was considered statistically significant after correction for 10 independent tests. Replication of significant associations found in the BMES sample was conducted in the Singapore Epidemiology of Eye Diseases (SEED) study (n = 10,033).

Results

No polymorphism was associated with prevalent cortical cataract. A significant interaction was observed between rs9640883 and FBG (Pinteraction = 0.004), with increased cortical cataract prevalence associated with rs9640883 minor allele dosage in those with FBG >6.0 mM (strata-specific OR 1.72, 95% CI 1.09-2.72). No similar association was found in participants with normal FBG (OR 0.85, 95% CI 0.69-1.04). This interaction was not evident in the SEED study.

Conclusions

The identified interaction between rs9640883 and FBG in relation to cortical cataract was not replicated but may warrant further investigation.

β2-AR regulates the expression of AKR1B1 in human pancreatic cancer cells and promotes their proliferation via the ERK1/2 pathway

Psychological stress has been recognized as a well-documented risk factor associated with β2-adrenergic receptor (β2-AR) in the development of pancreatic cancer. Aldo-keto reductase 1 member B1 (AKR1B1) is a potential interacting partner of β2-AR, but the effect of their interaction on pancreatic cancer cells is not known at present. We found a positive correlation between AKR1B1 and β2-AR expression in pancreatic cancer tissue samples, and co-localization of these proteins in the human pancreatic cancer BXPC-3 cell line. Compared to the controls, the CFPAC-1 and PANC-1 pancreatic cancer cells overexpressing β2-AR and AKR1B1 respectively showed significantly higher proliferation rates, which is attributed to higher proportion of cells in the S phase and decreased percentage of early apoptotic cells. Furthermore, overexpression of β2-AR led to a significant increase in the expression of AKR1B1 and phosphorylated extracellular signal-regulated kinase (p-ERK1/2). Overexpression of AKR1B1 significantly decreased β2-AR levels and increased that of p-ERK1/2. Taken together, β2-AR directly interacted with and up-regulated AKR1B1 in pancreatic cancer cells, and promoted their proliferation and inhibited apoptosis via the ERK1/2 pathway. Our findings also highlight the β2-AR-AKR1B1 axis as a potential therapeutic target for pancreatic cancer.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

Association of ARHGAP22 gene polymorphisms with the risk of type 2 diabetic retinopathy

BACKGROUND

Little is known about the contribution of ARHGAP22 polymorphism to diabetic retinopathy (DR) risk. We performed a case-control study to investigate the associations between ARHGAP22 and the risk of DR in a Chinese Han population.

METHODS

A total of 341 patients with type 2 diabetes mellitus (T2DM) were selected. All patients underwent a complete eye examination. Based on this, the patients with T2DM were divided into two subgroups: 188 patients with DR and 153 patients without DR. Five single nucleotide polymorphism (SNPs) were selected and genotyped using the MassARRAY method (Sequenom, San Diego, CA, USA). The odds ratio (OR) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression adjusted for age and sex.

RESULTS

Two susceptibility SNPs in ARHGAP22 were found to be associated with an increased risk of DR both before and after the adjustment: rs10491034 under the dominant model (adjusted OR = 0.51, 95% CI = 0.27-0.95, p = 0.032) and additive model (adjusted OR = 0.47, 95% CI = 0.26-0.84, p = 0.0098) and rs3844492 under the codominant model (adjusted OR = 3.14, 95% CI = 1.10-9.01, p = 0.023) and recessive model (adjusted OR = 3.52, 95% CI = 1.26-9.85, p = 0.011).

CONCLUSIONS

Our findings reveal a significant association between SNPs in the ARHGAP22 gene and DR risk in a Han Chinese population.