PDCD1 and rheumatoid arthritis: Additionally, recent studies have reported that a single-nucleotide polymorphism (SNP) in PDCD1 is associated with the development of autoimmune diseases (SLE, type 1 diabetes, progressive MS, Vogt-Koyanagi-Harada disease, Graves' disease, and RA), suggesting that PDCD1 may be involved in the maintenance of tolerance (20, 108).