YKL-40, also named chitinase 3-like 1 (Chi3l1) [5, 6], produced by a number of different cell types, including: cancer cells, macrophages, neutrophils [7–10], is an inflammatory glycoprotein involved in endothelial dysfunction by regulating chemotaxis, cell attachment and migration, reorganization as a response to endothelial injury [11]. The gene discussed is CHI3L1; the disease is endothelial dysfunction.