Rheumatoid arthritis has a strong correlation with serum resistin levels.14 Kisacik et al. reported that resistin levels could be useful in diagnosing FMF patients with attacks, but it was not useful in the differential diagnosis of acute appendicitis.15 In the present study, resistin studied in both attack and attack-free situations was significantly higher in FMF patients than in healthy individuals and was predictive of disease according to logistic regression analysis. This evidence concerns the gene RETN and familial Mediterranean fever.