Aicardi Syndrome

Patient Information

Characteristics

Background and History

Aircardi syndrome is a rare multisystem disorder first described by a French neurologist, Jean Dennis Aicardi in 1965. It occurs almost exclusively in females although rare males with chromosomal abnormalities have also been described.

Clinical Correlations

This disorder is often diagnosed in infants and young children with spasms or seizures, and developmental delay resulting from failure of the brain to develop normally. The facial appearance is considered distinctive with a narrow nasal bridge, upturned tip of the nose, and a narrow nasal bridge. There is a wide range of severity in this disorder as only some patients have seizures, and, while some have significant mental retardation, others can function at a near normal level.

Genetics

Inheritance

The genetic defect causing this disorder is presumed to reside on the X chromosome since, with rare exceptions, only females have been diagnosed. No specific mutation has been identified, however. It is presumed that most cases are due to new mutations since it is almost never found in siblings. The reason for the absence of affected males is considered to result from the presumed lethal nature of the genetic defect in males who, of course, have only one X chromosome and lack a second one that would aid in modifying the effects of the mutation. The majority of cases are presumed to result from new mutations as familial cases are exceedingly rare.

Pedigree

X-linked dominant, father affected

X-linked inheritance patterns result when disease-causing mutations are located on the X chromosome. Males have one X chromosome while females have two. A mutation on the male's X chromosome frequently is lethal or renders him unable to reproduce. However, in rare cases when males have children, they can expect that all of then will inherit the condition.

Sanple pedigree of X-linked dominant inheritance, father affected — X-linked inheritance patterns result when disease-causing mutations are located on the X chromosome. Males have one X chromosome while females have two. A mutation on the male's X chromosome frequently is lethal or at least renders them unable to reproduce. However, in rare cases when males have children, they can expect that all of then will inherit the condition.

X-linked dominant, mother affected

X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.

Diagnosis and Prognosis

The diagnosis can only be made by a physician who recognizes the facial characteristics in association with the neurological symptoms and the MRI abnormalities in the brain. Blood studies are not helpful in Aicardi syndrome. This disorder is apparently stable with no evidence of progression. No treatment is available.