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What causes agenesis of the corpus callosum? 1 possible condition

Your corpus callosum is a structure that connects the right and left sides of your brain. "Agenesis" is a word that means "not formed" or "absence of an organ." Agenesis of the corpus callosum is a birth defect that occurs when the connections between the right and left hemispheres of your brain don’t form correctly.

What is agenesis of the corpus callosum?

The corpus callosum is a curved structure that connects the right and left sides of your brain. It contains 200 million nerve fibers that pass information back and forth. Agenesis of the corpus callosum (ACC) occurs when the nerve fibers that make up your corpus callosum don’t form correctly. It occurs as a birth defect, which means it’s present at birth.

If you have a child born with ACC, they can survive with the condition. However, it may cause a variety of issues over their lifetime.

Other terms used to refer to specific forms of ACC include:

  • partial corpus callosum agenesis
  • hypogenesis of the corpus callosum
  • hypoplasia of the corpus callosum
  • dysgenesis of the corpus callosum

ACC is the most common cerebral malformation. It may affect as many as seven out of every 1,000 people, reports the National Organization for Rare Disorders (NORD).

What are the symptoms of ACC?

In some cases, ACC doesn’t cause dramatic symptoms. It often causes developmental delays, which may be mild or more severe.

For example, ACC can cause delays in your child’s development of motor skills, such as sitting, walking, or riding a bike. It can potentially cause feeding problems and swallowing difficulties. Poor coordination is also common. Your child may also experience some language and speech delays in expressive communication. While cognitive impairment can occur, many individuals with ACC have normal intelligence.

Other symptoms of ACC include:

  • seizures
  • vision problems
  • hearing impairment
  • chronic constipation
  • low muscle tone
  • high pain tolerance
  • sleep difficulties
  • social immaturity
  • trouble seeing other people’s points of view
  • difficulty interpreting facial expressions
  • poor understanding of slang, idioms, or social cues
  • difficulty separating truth from untruth
  • difficulty with abstract reasoning
  • obsessive behaviors
  • attention deficit
  • fearfulness

What causes ACC?

ACC is a congenital birth defect. That means it’s present at birth. A variety of risk factors can increase your child’s chances of developing ACC.

Your child’s corpus callosum forms late in the first trimester of pregnancy. Exposure to certain medications during this period, such as valproate, is one risk factor for the condition. Exposure to illicit drugs and alcohol is another. If your child’s birth mother develops certain viral infections during pregnancy, such as rubella, it can also cause ACC.

Chromosomal damage and abnormalities can also raise your child’s risk of ACC. For example, trisomy is linked to ACC. In trisomy, your child has three copies of chromosome 8, 13, or 18 instead of two.

Most cases of ACC occur alongside other brain abnormalities. For example, if cysts develop in your child’s brain, they can block the growth of their corpus callosum and cause ACC. Other conditions that can be associated with ACC include:

  • Arnold-Chiari malformation
  • Dandy-Walker syndrome
  • Aicardi syndrome
  • Andermann syndrome
  • acrocallosal syndrome
  • schizencephaly, or deep clefts in your child’s brain tissue
  • holoprosencephaly, or failure of your child’s brain to divide into lobes
  • hydrocephalus, or fluid in your child’s brain

Some of these conditions are genetic disorders.

How is ACC diagnosed?

If your child has ACC, their doctor may detect it before they’re born, during a prenatal ultrasound scan. If they see signs of ACC, they may order an MRI to confirm diagnosis.

In other cases, your child’s ACC may go undetected until after birth. If their doctor suspects they have ACC, they can order an MRI or CT scan to check for the condition.

What are the treatments for ACC?

There’s no cure for ACC. But your child’s doctor can prescribe treatments to help manage their symptoms. For example, they may recommend medications to control seizures. They also recommend physical, speech, or occupational therapy to help your child manage other symptoms.

Depending on the severity of their condition, your child may be able to lead a long and healthy life with ACC. Ask their doctor for more information about their specific condition, treatment options, and long-term outlook.

Content licensed from:

Written by: Christine Case-Lo
Medically reviewed on: Jan 03, 2017: University of Illinois-Chicago, College of Medicine

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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