The corpus callosum is a structure that connects the right and left sides of the brain. It contains 200 million nerve fibers that pass information back and forth.

Agenesis of the corpus callosum (ACC) is a birth defect that occurs when the connections between the right and left sides of a child’s brain don’t form correctly. It occurs in an estimated 1 to 7 out of 4,000 live births.

There are several specific forms of ACC, including:

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

A child that’s born with ACC can survive with the condition. However, it may cause developmental delays, which can be mild or more severe.

For example, ACC can cause delays in a child’s development of motor skills, such as sitting, walking, or riding a bike. It can potentially cause difficulties with swallowing and feeding. Poor coordination is also common in children with this condition.

A child may also experience some language and speech delays in expressive communication.

Although cognitive impairment can occur, many people with ACC have normal intelligence.

Other potential symptoms of ACC include:

ACC is a congenital birth defect. That means it’s present at birth.

A child’s corpus callosum forms late in the first trimester of pregnancy. A variety of risk factors can increase the chances of developing ACC.

During the first trimester of pregnancy, exposure to certain medications, such as valproate, raises a child’s risk of developing ACC. Exposure to certain drugs and alcohol during pregnancy is another risk factor.

If your child’s birth mother develops certain viral infections while pregnant, such as rubella, it can also cause ACC.

Chromosomal damage and abnormalities can also raise a child’s risk of ACC. For example, trisomy is linked to ACC. In trisomy, your child has an extra copy of chromosome 8, 13, or 18.

Most cases of ACC occur alongside other brain abnormalities. For example, if cysts develop in a child’s brain, they can block the growth of their corpus callosum and cause ACC.

Other conditions may also be associated with ACC, including:

Some of these conditions are caused by genetic disorders.

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 the 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.

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 may also recommend speech, physical, 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.

ACC is a birth defect that can cause mild to severe developmental delays. Environmental and genetic factors can play a role in its development.

If you have a child with ACC, their doctor may recommend medications, rehabilitation therapy, or other treatments to help manage their symptoms. Their doctor can provide more information about their treatment options and long-term outlook.