Indeed, circulating CDA was shown to be increased in several conditions including septicemia, metastasis and rheumatoid arthritis as well as in systemic lupus erythematosus patients [36, 39–42, 47, 48], and whereas uridine levels do not differ, plasma cytidine levels may be lower in adults than in infants [13]. This evidence concerns the gene CDA and rheumatoid arthritis.