Aicardi syndrome is a rare genetic disorder affecting females only (ie it is X-linked). There is a partial or complete absence of the corpus callosum, the part of the brain which sits between the right and left sides of the brain and allows the right side to communicate with the left. Characteristics and symptoms of the syndrome are infantile spasms, mental retardation, lesions or "lacunae" of the retina of the eye that are very specific to this disorder, and sometimes other types of defects of the brain such as microcephaly (small brain; enlarged ventricles) or proencephalic cysts (a gap in the brain where there should be healthy brain tissue).
Children are most commonly identified with Aicardi syndrome between the ages of three and five months. A significant number of these girls are products of normal births and seem to be developing normally until around the age of three months, when they begin to have infantile spasms. The onset of infantile spasms at this age is due to closure of the final neural synapses in the brain, a stage of normal brain development. The known age range of affected children is from birth to the mid - 20's. The disease was identified by French neurologist, Dr. Jean Aicardi in 1965. This syndrome is defined as a "rare disorder" , meaning that there are less than 20,000 cases worldwide.
The number of identified cases of girls with Aicardi syndrome is approximately 300-500 worldwide.