Thereafter, increased levels of IFN biological activity were documented in the serum of individuals suffering from various systemic autoimmune diseases (SADs) including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), and Sjogren’s syndrome (SS) (Skurkovich et al., 1977; Hooks et al., 1979; Ytterberg and Schnitzer, 1982). Here, IFNA1 is linked to systemic sclerosis.