Therefore, we aimed to investigate the prevalence of PHOMS in patients with (i) aquaporine-4-IgG-positive (AQP4) neuromyelitis optica spectrum disorders (AQP4 + NMOSD) and (ii) myelin oligodendrocyte glycoprotein-IgG (MOG)-associated disease (MOGAD). This evidence concerns the gene MOG and neuromyelitis optica.