Aicardi syndrome is an extremely rare genetic disorder. Almost all people with Aicardi syndrome are females. Individuals with Aicardi syndrome have agenesis of the corpus callosum, chorioretinal lacunae and seizures. Agenesis of the corpus callosum means that the structure that connects the right half of the brain with the left half of the brain (corpus callosum) does not develop normally. Chorioretinal lacunae are small holes in the retina (back part of the eye). These are only visible to a doctor using a device to look into the back of the eye. It is very unusual (maybe impossible) to have Aicardi syndrome without having chorioretinal lacunae. The seizures can be of different types. Infants with Aicardi syndrome usually have a type of seizures known as "infantile spasms". These are single jerks of the whole body. They may happen many times a day. Infants are usually awake during infantile spasms. These look different from the more common type of seizures known as "generalized tonic-clonic" seizures. Generalized tonic-clonic seizures are rhythmic jerking of arms and legs. People often out during this type of seizure. Children with Aicardi syndrome usually grow out of infantile spasms and then have generalized tonic-clonic or other types of seizures. Other parts of the brain also do not develop normally. These brain malformations cause frequent seizures and intellectual disability.

Aicardi syndrome symptoms usually appear in babies between the ages of 2 and 5 months old. Your child may begin jerking or having infantile spasms, a type of seizure that occurs in infants. These Seizures can develop into epilepsy later in life. Your child may also develop yellowish spots on their eyes. Lesions on the retina, which is the light-sensitive layer of tissue at the back of the eye, cause these spots.

Other symptoms of Aicardi syndrome include:

• a coloboma, which is a hole or gap in one of the structures of the eye
• abnormally small eyes
• an unusually small head
• hand deformities
• intellectual disabilities
• developmental delays
• difficulty eating
• diarrhea
• constipation
• gastroesophageal reflux
• spasticity, which is a condition that causes stiff and rigid muscles

Additional symptoms of Aicardi syndrome include rib and spine abnormalities, such as scoliosis. Children with this disorder may also have unusual facial features, such as a flatter nose, larger ears, or a smaller space between the upper lip and nose. Since Aicardi syndrome can result in poorly developed eyes, children may experience impaired vision or blindness.

Researchers have also found that the brains of children with Aicardi syndrome may have fewer folds and grooves than a normal brain. Fluid-filled cysts may also be present in the brain.

Aicardi syndrome most often appears in females as well as in boys with Klinefelter’s syndrome, a condition in which a male has an extra X chromosome. For these reasons, researchers believe the disorder is caused by a defect on the X chromosome.

People normally have 46 chromosomes in each cell. Two of the 46 chromosomes are sex chromosomes, known as X and Y. They help determine whether someone will develop male or female sex characteristics. Females have two X chromosomes, while males usually have one X chromosome and one Y chromosome.

During the normal development of an embryo, there should only be one active X chromosome in each cell. This means that one of the two X chromosomes in a female embryo must randomly deactivate during cell formation. In the case of Aicardi syndrome, researchers think that the deactivation of the X chromosomes fails to alternate randomly. As a result, one X chromosome is active in more than half of the body’s cell formations. This is called “skewed X-inactivation.”

Researchers have yet to determine the exact gene that causes skewed X-inactivation, so the cause of the disorder is still not known. This lack of information also makes it difficult to determine the risk factors for Aicardi syndrome.

Medications may be used to suppress the seizures caused by Aicardi syndrome. The seizures are often hard to treat. The doctor may need to try a number of medicines to see which medication works best. Studies have shown that there is not one medicine that works for everyone with Aicardi syndrome.

Aicardi syndrome usually affects only females. In very rare cases, males with Klinefelter syndrome (47,XXY) may have Aicardi syndrome. It has been estimated that there are between 300 and 500 cases of Aicardi syndrome worldwide. There do not appear to be any differences based on ethnicity or gender.