Causal Relationship between SLE and Chondromalacia patella-a two-sample Mendelian Randomisation Study

Systemic lupus erythematosus (systemic lupus erythematosus, SLE) may affect the development of chondromalacia patellae (CMP) through immune mechanism; in order to investigate the causal effect between SLE and chondromalacia patellae, genome-wide association study (GWAS) was conducted in a large European population. GWAS), mutually independent loci associated with SLE and chondromalacia patellae respectively were extracted as instrumental variables (SNPs), and three Mendelian randomisation (MR) analyses were applied to investigate the causal relationship, i.e., inverse variance weighting, weighted median and MR-Egger. To verify the robustness of the results, heterozygosity was used. To verify the robustness of the results, sensitivity analyses were performed using heterogeneity, multiplicity tests and the "leave-one-out" method. The results of the inverse variance weighting method showed that the OR (95% CI) between SLE and chondromalacia patella was 1.152 (1.063-1.248), P= 0.535E-03, indicating a causal relationship between SLE and chondromalacia patella. The results of this study all passed the heterogeneity and multiplicity tests and the sensitivity analysis results also showed reliable results. In this study, using two-sample MR analysis, SLE was found to be a risk factor for chondromalacia patella from a genetic point of view, and patients with SLE should be prevented or detected and treated early for chondromalacia patella. [Abbreviations] SLE = systemic lupus erythematosus; GWAS = genome-wide association study; IVW = inverse variance weighting; MR = Mendelian randomisation; SNP = single nucleotide polymorphism