About Disorders of the Corpus Callosum.

The Corpus Callosum is a bundle of more than 200 million nerve fibres that form the major pathway connecting the two hemispheres of the brain.  Its primary function is to transfer information for motor, sensory and cognitive activity between the left and right hemispheres

The Corpus Callosum forms in the early part of the development of a foetus, 12 -16 weeks into a pregnancy.  The entire structure is developed at birth but continues to thicken after birth becoming more effective and efficient.  By around the age of 12, the  Corpus Callosum is basically functioning as it will in adulthood.

Although the Corpus Callosum is the major path between the hemispheres, other smaller connections do exist.  The Anterior Commissure has about 50 thousand nerve fibres and the Posterior Commmissure and Hippocampal Commissure are smaller again.

When looking at a MRI the cross section of the Corpus Callosum is the white almost like a horse shoe shaped piece.

Read more about disorders of the corpus callosum and ausDoCC in:

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A disorder of the Corpus Callosum (DCC) is a rare, congenital, neurological condition.  DCC is the umbrella term for several conditions  in which the Corpus Callosum fails to develop properly, either partially, thinly or doesn't  form at all.

A disorder of the Corpus Callosum is a congenital abnormality of the brain and as such is not a disease or an illness.

If the Corpus Callosum  fails to develop during the first part of the pregnancy, it will not develop later.  If the Corpus Callosum has formed partially or thinly it will not regress.

Types of DCC's


Corpus Callosum Development
Terms/names used to describe
Common abbreviations
 Missing entirely/ absent
  •  Agenesis of the Corpus Callosum
  • Complete Agenesis of the Corpus Callosum
  • ACC
  • C-ACC
  • AgCC
  • C-AgCC 
 Incomplete/partially absent/malformed
  •  Agenesis of the Corpus Callosum
  • Partial Agenesis of the Corpus Callosum
  • Hypogenesis of the Corpus Callosum
  • Dysgenesis of the Corpus Callosum
  •  ACC
  • P-ACC
  • AgCC
  • P-Agcc
 Present Corpus Callosum but significantly thin
  •  Hypoplasia of the Corpus Callosum
  •  HCC

Agenesis means the failure of all or part of an organ to develop during embryonic growth.  (http://www.britannica.com/EBchecked/topic/8985/agenesis)

Agenesis of the Corpus Callosum

Agenesis of the Corpus Callosum means that during those early weeks of development the Corpus Callosum failed to develop fully or partially.  Both these condition can fall under the heading of Agenesis of the Corpus Callosum or the abbreviation of ACC or AgCC.

Partial is sometimes described on its own as missing only part of the body of the Corpus Callosum and has the abbreviation of P ACC.


  • Hypoplasia of the Corpus Callosum

Hypoplasia from the Greek  - Hypo meaning under and Plasis meaning formation.

Hypoplasia of the Corpus Callosum means that during the early weeks of development while the Corpus Callosum has formed it is under developed and thin.


  • Dysgenesis of the the Corpus Callosum

Dysgenesis means defective or abnormal development of an organ in this case the Corpus Callosum.

Dysgenesis of the Corpus Callosum means that during development the Corpus Callosum while it has developed it has developed in some incomplete or abnormal way.

Dysgensesis can also be used as a broad, general term for  the various types of Disorders of the Corpus Callosum including Partial, Full or Hypoplasia.

There is little research available that shows the effects of the different types of disorders will have on a person.  When we refer  to Disorders and the effects we are in fact covering all the above.

It is hard to determine the exact cause of why the Corpus Callosum failed to properly develop.

Possible causes include

  • Genetic abnormalities (abnormalities in the structure of chromosomes or the genes within them)  With a genetic cause, other organs may also be affected and the child may be diagnosed with a syndrome such as Aicardi syndrome or Andermann syndrome.
  • Non-genetic causes (such as exposure of the fetus to toxins or infections).
  • Blockage of the growth caused for example by a cyst.
  • For some there will never be an answer to the question, which for a parent especially a mother can be the hardest part.  Over the years in discussions with other parents a variety of causes has been put forward, from painting a room to taking a particular medicine to a mother’s health, but while some will speculate on what has caused the disorder, remember it happened very early in the pregnancy and there has been no research to prove it was something that could be prevented.

A disorder of the Corpus Callosum is usually made with a MRI at some point after birth. For some a MRI is ordered due to developmental delays and looking for answers.  For others it could be after unexplained head aches and as an adult an answer so unexpected but an answer that puts all the past into place.

It is also being diagnosed before during an prenatal ultrasound, where enlarged ventricles can point to other problems or a specific problem with the Corpus Callosum is seen.  This can be followed up by a MRI on the developing baby and further screening after the baby is born.

A baby who ends up in the Neonatal Intensive Care Unit will as part of their stay have a head ultrasound done and the disorder can be picked up at this point.  Further imaging will be needed to confirm the exact disorder.

A Disorder of the Corpus Callosum is a rare congenital birth defect.  It is hard in Australia to give any sort of figures to say how common it is, to our knowledge, no real statistics have been kept.   The statistics from the USA suggest that it could be around 1 :4000 births.

- A DCC can occur alone, with other abnormalities or as part of a syndrome,

- DCCs affect individuals very differently with the range of impact being anywhere from mild (such as normal development with some difficulties in higher cognitive processes) right through to severe disability (such as intellectual disability/ cerebral palsy),

- More commonly documented difficulties and secondary conditions include; developmental delay, seizures, disorders in emotion or behaviour regulation, high pain tolerance, autism, cerebral palsy, learning impairments and social difficulties,

- Early intervention services are recommended for children diagnosed with a DCC.





ausDoCC are committed to providing the public with correct and current information regarding information about  the Corpus Callosum and associated disorders.  We are parents, caregivers and people with or caring for someone with a DCC.  The information provided in this section is from our research and put into language that non medical people can understand. But it is always our advice to discuss information found on this site and in particular these information pages with your medical provider.