Handbook of Genetic Counseling/Hypoplasia - Agenesis of the Corpus Callosum

Hypoplasia - Agenesis of the Corpus Callosum

Definition

The area of the brain (large fiber tract) which permits the exchange of information between the left and right cerebral hemispheres.
"the seat of the soul". Used to be that the thickness of its body was related to the level of intelligence.
Function is uncertain because there is no consistent pattern when it is malformed or absent.
Embryology: forms between 9-16 weeks of development. anterior to posterior.

rare; no specific numbers

ACC is usually diagnosed between 0-2 years (by MRI or CT scan) but may never be dx.
May occur as severe syndrome, a milder condition, or an asymptomatic finding
Signs and Symptoms:
- Seizures (infantile spasms)
- Feeding problems
- Delays in holding head erect, sitting, standing and walking
- microcephaly

Deficit or delay in mental and physical development, hand-eye coordination and/or visual and auditory memory
Could also include: hydrocephaly, seizures, dyskinesia, repetitive speech, headaches

Most are isolated/sporadic
Males and females equally affected
May be caused by a genetic syndrome such as:
- Aicardi's syndrome: ACC, infantile spasms, severe mental retardation and chorioretinal lacunae
- Grubben syndrome
- Wolf-Hirschhorn syndrome: chromosome abnormality
- Opitz-Frias syndrome
- Joubert syndrome
- X-linked syndromes: Bertini, Opitz-Kaveggia, Orofaciodigital, Proud, Pyruvatedehydrogenase
May be associated with other cerebral anomalies such as Arnold-Chiari malformation, Dandy-Walker syndrome, Andermann syndrome, schizencephaly, holoprosencephaly and migrational anomalies
Sometimes associated with complex multi-system anomalies and chromosomal abnormalities (trisomy 13 and 18).

No specific treatment. May involve managing treatment of other conditions such as hydrocephaly and seizures if they occur

Excellent in most isolated cases
Does not cause death in vast majority
Many will lead normal lives and have average intelligence
Children w/ ACC and DD and/ or seizures should be screened for metabolic disorders.
Mental retardation is not progressive

NINDS Agenesis of the Corpus Callosum Information Page www.ninds.nih.gov/health_and _medical/disorders/agenesis_doc.htm
Agenesis of the Corpus Collosum. Mental Retardation and Congenital Malformations of the Central Nervous System. Warkany, J, Lemire, R, Cohen, M.
Human Embryology. Larsen, WJ.

The information in this outline was last updated in April 2003.