The shared genetic etiology of autoimmune disorders and interstitial lung disease: insights from large-scale genome-wide cross-trait analysis.

Autoimmune diseases often co-occur with interstitial lung disease (ILD), and ILD is associated with patient prognosis. Research has demonstrated a relationship between autoimmune diseases and ILD; however, the genetic basis underlying this connection is frequently overlooked. Linkage disequilibrium score regression and high-definition likelihood methods were applied to large-scale genome-wide association studies summary-level data sets to assess genetic correlations between 17 autoimmune disorders and ILD. Several functional annotations and tissue-specific analyses were performed to determine the influence of pleiotropic genes based on the pleiotropy analysis method under the compound null hypothesis method. Eight autoimmune disorders were revealed sharing genetic mechanisms with ILD. A total of 107 pleiotropic loci were identified at the genome-wide significance level (P < 5 × 10-8), 18 of which had strong evidence of colocalization. Multiple potential pleiotropic genetic loci were identified, particularly the SMO gene located 7q32.1 locus. Pathway analysis determined in bound by FOXP3, T cell selection, and regulation of immune response. SNP- and gene-level tissue enrichment revealed that pleiotropic mechanisms play a critical role in spleen, whole blood, lung, and EBV-transformed lymphocytes. There are significant genetic correlations and potential causal mechanisms between autoimmune diseases and ILD. The findings of this study provide a deeper understanding of the genetic architecture of autoimmune diseases and ILD.