A study conducted on families with three different autoimmune diseases (SLE, Sjögren’s syndrome, and rheumatoid arthritis) identified 39 rare variants in immune-related genes, including TCR signaling pathway genes, especially PAK2 and PLCL1, signifying the role of a complex interaction of multiple genes in families with autoimmune diseases (37). The gene discussed is PAK2; the disease is rheumatoid arthritis.