RESUMEN
AIM: To assess whether there is a possible causal link between the intake of cheese and the risk of diabetic retinopathy (DR) utilizing a two-sample Mendelian randomization (MR) analysis. METHODS: The research data were obtained from summary statistics of genome-wide association studies (GWAS). Genetic loci closely related to cheese intake were extracted as instrumental variables (IVs), and DR was the outcome variable. The data were extracted from individuals of European ethnicity. The data of cheese intake consisted of 451 486 samples with 9 851 867 single nucleotide polymorphisms (SNPs), while the DR data consisted of 206 234 samples with 16 380 446 SNPs. Sixty-one genetic loci closely related to cheese intake were selected as IVs. MR analysis was performed by inverse-variance weighted (IVW) method and MR-Egger regression respectively. The causal relationship between cheese intake and DR was evaluated using odds ratios (ORs) and 95% confidence intervals (CIs). Egger-intercept test was used to test horizontal pleiotropy and sensitivity analysis was performed by leave-one-out test. RESULTS: The P value of the IVW method was less than 0.05, indicating a significant negative correlation between cheese intake and DR. MR-Egger regression showed that the intercept was 0.01 with a standard error of 0.022, and a P-value of 0.634, indicating no evidence of horizontal pleiotropy affecting the IVs related to the exposure factors. Besides, heterogeneity tests confirmed the absence of heterogeneity, and the "leave-one-out" sensitivity analysis demonstrated that the results were stable. CONCLUSION: Cheese intake is causally negatively correlated with the occurrence of DR, and cheese intake could reduce the risk of DR.
RESUMEN
AIM: To investigate the corneal endothelial cell density and morphology and central corneal thickness in the Guangxi Maonan and Han adolescent students of China. METHODS: Noncontact specular microscope (Topcon SP3000P, Tokyo, Japan) was performed in 133 adolescent students of Maonan nationality (M:F 54:79) and 105 adolescent students of Han nationality (M:F 50:55), 5 to 20y of age, who were randomly selected from 3 schools in Huanjiang Maonan Autonomous County of Guangxi Zhuang Autonomous Region of China. Parameters studied included endothelial cell density, mean cell area, coefficient of variation in cell size, percentage hexagonality and central corneal thickness. RESULTS: Endothelial cell density, mean cell area, coefficient of variation in cell size, percentage hexagonality and central corneal thickness in the study population were (2969.50±253.93) cells/mm(2), (339.23±29.44) µm(2), (29.96±4.07) %, (64.58±9.41) % and (523.71±32.82) µm in Maonan and (2998.26±262.65) cells/mm(2), (336.11±30.07) µm(2), (29.89±5.03) %, (64.91±11.64) % and (524.39±33.15) µm in Han, respectively. No significant differences were observed in endothelial cell density, mean cell area, coefficient of variation in cell size, percentage hexagonality and central corneal thickness between Maonan and Han (P=0.615, 0.659, 0.528, 0.551, 0.999). In Maonan and Han, we found age was negatively correlated with endothelial cell density and percentage hexagonality and positively correlated with mean cell area and coefficient of variation in cell size. Negative correlation was also found between central corneal thickness and age in Han, whereas no correlation was found in Maonan. CONCLUSION: There were no differences between Maonan and Han in corneal endothelial cell density and morphology and central corneal thickness. In these two nationalities, there were statistically significant decrease in endothelial cell density and percentage hexagonality with increasing age and statistically significant increase in cell area and coefficient of variation in cell size with increasing age. Central corneal thinned with increasing age in Han, whereas difference did not attain statistical significance in Maonan.