Several studies on SNPs of the YKL-40 encoding gene, CHI3L1, have documented that genetic variations of CHI3L1 have an impact on circulating YKL-40-levels, both in healthy adults [18], [19] as well as in individuals with asthma[20], sarcoidosis[21], rheumatoid arthritis[18] and CAD[19]. This evidence concerns the gene CHI3L1 and rheumatoid arthritis.