AQP4 and amyotrophic lateral sclerosis: The pathomechanism of ALS is not well known, the compromised BBB integrity has been recognized as a possible factor for disease pathogenesis and progression.[4] Here, we report a female patient with ALS who had asymptomatic AQP4 antibody at the diagnosis of ALS, and NMOSD occurred 6 years later after the onset of ALS.