Targońska-Stȩpniak showed that there was no association between leptin levels, disease duration, and DAS28, however, in the group of patients with long-standing RA (duration of more than 10 years), a positive correlation was reported between serum leptin levels, DAS28, and the number of tender joints, suggesting an association between elevated serum concentrations and the aggressive course of RA [97]. The gene discussed is LEP; the disease is rheumatoid arthritis.