Aicardi Syndrome is a rare genetic disorder characterized by the partial or complete absence of the structure that links the two hemispheres of the brain, the corpus callosum. The disorder affects only girls. Onset of Aicardi Syndrome generally begins between the ages of 3 and 5 months with infantile spasms, a type of childhood seizure. Symptoms include seizures, mental retardation and lesions on the retina of the eye that are specific to the disorder. Aicardi Syndrome may be associated with other brain defects such as a smaller than average brain and cavities or gaps in the brain filled with cerebrospinal fluid.