ABCA1 and obstructive sleep apnea syndrome: The presents study substantially extends a smaller earlier study of 12 patients and 6 controls by Xu et al., which demonstrated reduced patients’ peripheral blood mononuclear cell (PBMC)-derived macrophage ability to efflux cholesterol through ABCA1, downregulation of the ABCA1 gene in macrophages of patients with OSA, and an inverse correlation of AHI with macrophage ABCA1 CEC and expression [42].