Aicardi syndrome: A genetic disorder characterized by the partial or complete agenesis of the corpus callosum (the structure that links the 2 hemispheres of the brain), infantile spasms (a characteristic form of childhood seizures), mental retardation, and an ocular (eye) abnormality called chorioretinal lacunae in which there are lacunae (holes) in the retina of the eye.

Aicardi syndrome may be associated with other brain defects such as microcephaly (small brain) or porencephalic cysts (cerebrospinal fluid-filled cavities or gaps in the brain). Features associated with Aicardi syndrome include cleft lip and/or palate, fatty tumors (lipomas) of the scalp, blood vessel malformations (cavernous hemangiomas), rib and vertebral defects and scoliosis (curved spine).

The genetics of Aicardi syndrome are extraordinary. The disorder affects only females. It is an X-linked dominant trait lethal in males. In a hemizygous male (whose only X chromosome contains the Aicardi gene), the Aicardi gene is fatal before birth. In a heterozygous female (with the Aicardi gene on one of her two X chromosomes), the Aicardi gene causes Aicardi syndrome. The Aicardi gene has been charted to the short (p) arm of the X chromosome and is in band Xp22.

There is no cure for Aicardi syndrome. Nor is there a standard course of treatment. Treatment is purely symptomatic. It generally involves management of seizures and programs for the mental retardation.

The prognosis for individuals with Aicardi syndrome varies according to the presence and severity of symptoms.