CHI3L1 and rheumatoid arthritis: Moreover, Petersson et al. (2006) also reported that arginine-vasopressin (AVP) and parathyroid hormone-related peptide (PTHrP) stimulated YKL-40 secretion particularly in RA chondrocytes 26,32, while Nielsen et al. suggested the association between the g.-131 (C > G) promoter SNP in the CHI3L1 gene and the serum concentration of YKL-40 49.