Genetic investigations of autoimmune diseases are key for understanding molecular mechanisms underlying disease pathogenesis. In this work, we aim to conduct genetic investigations, including genome-wide association analysis, mendelian randomization, polygenic risk scores, colocalization analysis, and more, to understand the genetic factors triggering the immune system. Genetic analyses will be conducted in diverse ethnic populations with well-phenotyped clinical data and molecular phenotypes. Using high-throughput sequencing and SNP-array technologies coupled with cutting-edge bioinformatics and statistical methods, we intend to elucidate the underlying genetic architecture of autoimmune diseases, chiefly rheumatoid arthritis and sarcoidosis, as well as other autoimmune diseases that are relevant to our studies.