2.1 Data sources and study design
To explore the causal relationship between IMIDs and AA, we utilized summary genetic association datasets of European ancestry for both IMIDs and AA from the IEU OpenGWAS Database Project (https://gwas.mrcieu.ac.uk/). The GWAS summary statistics for AA (GWAS ID: finn-b-I9_AORTANEUR) were obtained from the FinnGen cohorts’ Aortic aneurysm GWAS summary statistics, which included 2,825 cases and 206,541 controls with 16,380,417 SNPs (https://r5.finngen.fi/pheno/I9_AORTANEUR). In FinnGen Release 5, the diagnostic criteria for AA are defined in the following link (https://r5.risteys.finngen.fi/phenocode/I9_AORTANEUR). The GWAS datasets for IBD, CD, and UC were established by FinnGen Biobank with the respective GWAS ID numbers of ”finn-b-K11_IBD”, ”finn-b-K11_CROHN” and ”finn-b-K11_ULCER”. Specifically, the GWAS study related to IBD involved 5,673 cases and 213,119 controls and was further divided into K11_CROHN (2,056 cases and 210,300 controls) and K11_ULCER (4,320 cases and 210,300controls) endpoints. The PSO dataset, identified by the GWAS ID ”finn-b-L12_PSORIASIS”, was also received from FinnGen Biobank and comprises a sample size of 4,510 cases and 212,242 controls. The GWAS datasets associated with RA and SLE were obtained from European Bioinformatics Institute under the ID numbers ”ebi-a-GCST90013534” (14,361 cases and 43,923 controls) (26) and ”ebi-a-GCST003156” (5,201 cases and 9,066 controls) (27), respectively. Detailed information of these GWAS datasets are provided in Supplementary Table S1. Based on requirements of STROBE-MR standards(28), we report the design, methods and results analysis of this study. Schematic representation of this MR study is presented in Figure 1A.