Table 1
Characteristics of selected genome-wide association studies.
| OUTCOMES | CONSORTIUM | SAMPLE SIZE (CASES/CONTROLS) | POPULATION | UNIT |
|---|---|---|---|---|
| DM-PAD | NA | 11,197/225,597 | European | Event |
| eQTLs | eQTLGen | 31,684 | European | NA |
| BMI | GIANT | 681,275 | European | NA |
| Triglycerides | UK Biobank | 441,016 | European | NA |
| HDL cholesterol | UK Biobank | 403,943 | European | NA |
| LDL cholesterol | UK Biobank | 173,082 | European | NA |
[i] DM-PAD, diabetes mellitus-peripheral artery disease; eQTLs, expression quantitative trait locus; BMI, body mass index; HDL, high-density lipoprotein cholesterol; LDL, low-density lipoprotein cholesterol.
Figure 1
Schematic diagram of MR analysis. Assumption 1: Indicated by the solid line, the instrumental variants directly influence the expression of genes. Assumption 2: Represented by dashed lines, the instrumental variables are not associated with any potential confounders. Assumption 3: The instrumental variables affect the outcome solely through the exposure without any involvement in other causal pathways.
Figure 2
Identification of candidate risk genes for DM-PAD by using SMR analysis. A. Flowchart of the study. DM-PAD, diabetes mellitus–peripheral artery disease (SMR, summary-data-based Mendelian randomization; HEIDI, heterogeneity in dependent instruments; FDR, false discovery rates; MVMR, multivariable mendelian randomization). B. Volcano plot of causal effect between genes and DM-PAD: The abscissa represents bSMR, while the ordinate represents –log10(FDR). Red squares indicate high-risk candidate genes for DM-PAD, while blue squares represent low-risk candidate genes. Genes with black text labels represent those that passed the HEIDI test with a p-value >0.01. C. The dot-plot graph illustrates the impact of 15 risk candidate genes on DM-PAD, with |bSMR| values influencing the size of the dots and FDR determining their color (FDR, false discovery rate; DM-PAD, diabetes mellitus–peripheral artery disease).
Figure 3
Further exploration of risk genes for DM-PAD through the integration of SMR and two-sample MR analyses. A. Forest plot showing the odds ratios (OR) for associations between candidate genes and DM-PAD risk in two-sample MR analysis. B. Forest plot illustrating the OR for the associations between C4A, DENND5B, and CYP21A2 and the risk of DM-PAD in two-sample MR and SMR analysis. The FDR was calculated using the Benjamini–Hochberg method. C–E. Plotting effect sizes from DM-PAD GWAS against those from eQTL in DENND5B (C), CYP21A2 (D), and C4A (E). The r2 value represents the linkage disequilibrium between the top cis-eQTL and other cis-eQTL. Red triangles represent the top cis-eQTL, while blue circles represent other cis-eQTL (OR, odds ratios; DM-PAD, diabetes mellitus–peripheral artery disease; SMR, summary data-based Mendelian randomization; FDR, false discovery rate; eQTL, expression quantitative trait locus).
Figure 4
Elucidating the association between DENND5B and DM-PAD. A. Colocalization of genetic associations for DENND5B gene expression in the whole blood levels, and risk of DM-PAD. Each dot represents an SNP, with its color indicating the linkage disequilibrium (LD) (r2) with the GWAS lead variant, which is displayed as a purple diamond. The p-values from both the DM-PAD GWAS and the DENND5B gene expression analysis are compared. B. Genomic positions on chromosome 12 are displayed on the x-axis, while the –log10 p-values for SNPs from the DM-PAD GWAS (bottom) and the eQTL study for the DENND5B gene (top) are presented on the y-axis. C. Regional association plots for genetic DENND5B gene and DM-PAD GWAS data. D. Forest plot illustrated the MVMR results for the association between DENND5B gene and DM-PAD after statistically adjusts for other confounders including BMI and lipid traits (MVMR, multivariable Mendelian randomization; DM-PAD, diabetes mellitus–peripheral artery disease; eQTLs, expression quantitative trait locus; BMI, body mass index; HDL, high-density lipoprotein cholesterol; LDL, low-density lipoprotein cholesterol).
| DM-PAD | diabetes mellitus–peripheral artery disease |
| eQTLs | expression quantitative trait locus |
| MR | Mendelian randomization |
| MVMR | multivariate Mendelian randomization |
| SMR | summary data-based Mendelian randomization |
| Coloc | colocalization |