The plasma concentration of YKL-40 (also called chitinase3-like-1 (CHI3L1)) has attracted attention as a biomarker of disease activity in a wide array of diseases hallmarked by chronic low grade inflammation, tissue remodeling, and fibrosis, e.g. cardiovascular diseases[5-7], asthma[8], diabetes mellitus type 1[9] and 2[10,11], rheumatoid arthritis[12], liver fibrosis[13-15], and cancer[16]. This evidence concerns the gene CHI3L1 and rheumatoid arthritis.