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Hypoplasia - Agenesis of the Corpus Callosum
- underdevelopment (hypoplasia) complete absence (agenesis) of the CC
- 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
Possible clinical impairmentsEdit
- 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.
This material has been imported fom the wikibook "Genetic counseling"[ http://en.wikibooks.org/wiki/Genetic_counseling] under the GNU Free Documentation License.