It has been reported an increased YKL-40 expression in patients with carotid atherosclerosis [18], as well as a positive correlation between common carotid artery intima media thickness (CIMT) and YKL-40 levels in patients with obstructive sleep apnea syndrome [16] and between arterial stiffness and YKL-40 levels in essential hypertension subjects [15]. Here, CHI3L1 is linked to obstructive sleep apnea syndrome.