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

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Hypoplasia - Agenesis of the Corpus Callosum

DefinitionEdit

  • underdevelopment (hypoplasia) complete absence (agenesis) of the CC

Corpus collosumEdit

  • 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.

IncidenceEdit

rare; no specific numbers

DiagnosisEdit

  • 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

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

EtiologyEdit

  • 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).

ManagementEdit

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

PrognosisEdit

  • 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

ResourcesEdit

  • 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.

NotesEdit

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

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