While aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies were negative, a significantly elevated concentration of soluble interleukin-2 receptor (sIL-2R) in the CSF (96.1 U/mL; normal <8 U/mL) supported the diagnosis of neurosarcoidosis. This evidence concerns the gene AQP4 and neurosarcoidosis.