GFAP and myeloid sarcoma: Finally, studies in CSF have consistently found that GFAP is higher in patients with αAQP4+ and αMOG-/αAQP4- compared to αMOG+ patients and patients with MS or noninflammatory neurological controls; although in some analyses, the highest levels correlated with occurrence of myelitis rather than ON or brain lesions [62–64].