is a disorder of early brain development. The signs and symptoms vary from person to person; however, underdevelopment (hypoplasia) of the optic nerve, abnormal formation of structures along the midline of the brain, and pituitary hypoplasia are the characteristic findings. Recurring seizures, delayed development, and abnormal movements may be present in some people with septo-optic dysplasia. Although the exact cause of septo-optic dysplasia is unknown, it is believed that both genetic and environmental factors play a role. Viruses, medications, and blood flow disruption have all been suggested as possible environmental causes. Thus far, three genes (HESX1, OTX2, and SOX2) have been associated with septo-optic dysplasia. Typically, people do not have a family history of septo-optic dysplasia. However, there have been a few cases in which multiple family members have been diagnosed. Familial cases may follow an autosomal recessive or autosomal dominant pattern of inheritance. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.