Exploring the Genetic Association Between Connective Tissue Diseases and the Risk of Pulmonary Arterial Hypertension: A Mendelian Randomization Analysis.

This study aimed to explore the potential causal link between genetic predisposition to various connective tissue diseases (CTDs), namely systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), polymyositis (PM), dermatomyositis (DM), systemic sclerosis (SSc), mixed connective tissue disease (MCTD), and rheumatoid arthritis (RA), and the incidence of pulmonary arterial hypertension (PAH) utilizing Mendelian randomization (MR). Employing a two-sample MR approach, genetic variants associated with CTDs served as instrumental variables to investigate the exposure-outcome relationship, with GWAS data sourced from the FinnGen Biobank. Comprehensive statistical analyses, including the inverse variance weighted (IVW) method, were conducted, alongside heterogeneity, pleiotropy, and sensitivity tests to ensure the robustness and validity of findings. The results revealed that in the Finnish population, no significant causal associations were identified between PAH and SLE, SS, PM, DM, MCTD, or RA. Notably, a significant association was observed between SSc and an increased risk of PAH (IVW: OR = 1.278, 95% CI = 1.061-1.540,  = 0.010). However, this finding was not replicated in other European populations. These results indicate the unique genetic and pathological pathways underlying SSc-associated PAH, emphasizing the need for tailored screening and management protocols in this patient group.