APOA4 and obstructive sleep apnea syndrome: Clinical studies demonstrated that patients in the severe OSA group showed higher levels of APOA4 (285.84±47.97 pg/mL) than those with non-OSA or mild-moderate OSA (163.03±51.25 pg/mL and 237.32±49.80 pg/mL, p <0.01, and p  = 0.013, respectively; Fig 4A).