What is H-ABC?

Hypomyelination with Atrophy of the Basal Ganglia and Cerebellum, or H-ABC, is a rare, genetic disorder that targets two parts of the brain: the basal ganglia and the cerebellum. Both of which control the body’s actions and movements. Through the process of hypomyelination (where the body is unable to produce the correct amount of myelin, or white matter), the basal ganglia and the cerebellum shrink and are unable to properly function.

What Are the Symptoms of H-ABC?

Since H-ABC targets two areas of the brain responsible for action and movement, people with H-ABC will often suffer from motor problems and other related symptoms, such as:

  • Stiffness
  • Low muscle tone
  • Involuntary movements
  • Poor balance and coordination
  • Difficulty swallowing and speaking
  • Deafness
  • Nystagmus (uncontrolled, rapid eye movements)
  • Poor vision
  • Seizures

How Do You Get H-ABC?

H-ABC is one of the few genetic disorders that are not inherited. In other words, neither parent is a carrier and the chance of producing another child with H-ABC is little to none. Instead, H-ABC is caused by a mutation in the TUBB4A gene (a gene responsible for the formation of microtubules, which helps control cell division, motility, and transport) that occurs at random.

How is H-ABC Diagnosed?

A diagnosis for H-ABC is usually made through either an MRI scan that detects brain tissue patterns related to H-ABC, or through genetic testing that confirms the mutation of the TUBB4A gene.

Is There a Treatment for H-ABC?

As of now, there is no known cure for H-ABC. However, treatments are available to alleviate symptoms and improve an individual’s quality of life. For instance, a combination of physical therapy and certain medications can be instituted to improve motor skills and lessen involuntary muscle movements.

Helpful Resources

Foundation to Fight H-ABC


Children’s Hospital of Philadelphia