The goal of this study is to assess the frequency of genetic polymorphisms of the FCG3A in a cohort of Italian patients affected by neuromyelitis optica spectrum disorder (NMOSD) and mog antibody associated disease (MOGAD) and in a a comparison group of patients affected with Multiple Sclerosis (MS). The study will involve adult patients diagnosed with MS, NMOSD, or MOGAD, followed at various clinical centers in the Lazio region. Patients from the participating clinical centers will be selected, and their medical records will be analyzed to collect clinical and neuroimaging data. The data will include demographic information such as age, sex and body mass index and clinical information such as age at disease onset, disease duration, antibody status (AQP4+/- and MOG+/-), disease-modifying therapies, as well as MRI data and the Expanded Disability Status Scale (EDSS) score. Each patient included in the study will undergo a single blood draw of approximately 5 ml of peripheral venous blood during routine blood tests, which will be used for DNA extraction and polimorphysm analysis. Demographic and clinical differences between patients with NMOSD and MOGAD, with and without the polymorphism, will be assessed and compared with the group of patients with MS.