APOA4 and neuromyelitis optica: Neurofilament (NF), HP, immunoglobulin kappa chain C region (IGKC), immunoglobulin heavy chain gamma 3 (IGHG3) were upregulated; whereas alpha-1β-glycoprotein (A1BG), DBP, fibrinogen gamma chain (FGG), pigment epithelium-derived factor (PEDF), apolipoprotein A-IV (ApoA-IV), apolipoprotein E (ApoE), and transthyretin (TTR) were downregulated in the NMO group in comparison to the control group.