Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 7 6 2023 03 12 301 305 EN zahra ebadi Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran Fereshteh Ghadiri Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran Elnaz Asadollahzade Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran Abdorreza Naser Moghadasi Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran 2022 10 21 2022 11 27 Neuromyelitis Optica Spectrum Disorder (NMOSD) is an autoimmune rare disorder that involves the endfeet of astrocytes. The role of genetics in the disease is not well known. Rare cases of familial NMOSD were reported worldwide. In this report, first, we presented a young man with myelitis and his cousin who suffered from this disease. Then we reviewed some reports around the world about familial NMO. The prevalence of familial NMO is nearly 3%. First cases are reported from East Asia. Its characteristics are similar to the sporadic type. Recent data suggest genetics play role in NMO. https://crcp.tums.ac.ir/index.php/crcp/article/view/746