Aicardi Syndrome is a rare genetic disorder in which the structure that connects the two sides of the brain (the corpus callosum) is partly or completely missing.

The cause of Aicardi Syndrome is unknown at this time. Some think that, in some cases, is a result of a gene defect on the X chromosome. There are less than 500 cases of Aicardi Syndrome worldwide.

The disorder affects only girls.

Symptoms usually start when the child is between ages 3 and 5 months. The condition causes infantile spasms (jerking), a type of childhood seizure. Other symptoms include mental retardation and lesions on the retina of the eye or optic nerve.

Aicardi Syndrome may be associated with other brain defects.

Other symptoms may include:

• Abnormal ribs or spine
• Smaller-than-normal eyes (microphthalmia)
• Other eye problems, such as coloboma (cat's eye)
• Large differences in the size of the two halves of the brain

Children are diagnosed with Aicardi Syndrome if they meet the following criteria:

• Female sex (or XXY genotype male)
• Retinal lesions
• Seizures (typically beginning as infantile spasms)
• Complete or partial absence of the corpus callosum

However, in rare cases, one of the features, especially lack of development of the corpus callosum, may be missing. In such cases, the diagnosis can probably be made if two or more of the following criteria are present:

• Abnormal formations in the brain such as microgyria (the bumps on the brain are abnormally narrow)
• Periventricular and subcortical heterotopia, a misplacement of groups of neurons in the brain sometimes found in seizure disorders
• Cysts in specific areas of the brain
• Benign, non-cancerous tumor found in a specific section of the brain
• Optic disc or nerve coloboma

Tests to diagnose Aicardi Syndrome include:

• Eye exam
• CT scan of the head
• MRI
• EEG

Other procedures and tests may be performed depending on the individual person.