Signs & Symptoms of H-ABC/TUBB4A

A smiling boy sitting in a green and black stroller outdoors, with a person standing nearby wearing a polka dot skirt. There are benches and a building in the background.

Hypomyelination with Atrophy of the Basal Ganglia and Cerebellum (H-ABC) often begins in infancy or early childhood. Because each child is unique, symptoms can vary widely. Some children may show only mild challenges, while others face more significant obstacles. These differences can make the journey feel uncertain—but you are not alone. Early diagnosis and supportive care can make a meaningful difference, helping children manage symptoms and reach their potential.

H-ABC affects areas of the brain that control movement, coordination, and communication. As a result, children with H-ABC may face challenges with physical development, muscle control, speech, and learning.

  • When symptoms begin early in life, they may progress more quickly. Families may notice:

    • Low muscle tone (hypotonia): Babies may feel floppy or have difficulty holding up their heads.

    • Delays in movement milestones: Sitting, crawling, or walking may take longer to develop.

    • Poor coordination (ataxia): Movements may seem unsteady or clumsy.

    • Muscle stiffness (spasticity or rigidity): Muscles may feel tight or resist movement.

    • Involuntary movements: Children may have twisting or jerking motions that they can't control.

    • Feeding and speech difficulties: Swallowing or forming words can be harder due to muscle involvement.

    • Vision problems and eye movement difficulties (including nystagmus): Some children may have trouble focusing or tracking movement.

    • Small head size (microcephaly): In some cases, head growth may be below typical ranges.

    • Seizures: Seizures may develop and often require medical care and support.

  • If symptoms begin later, they may progress more slowly and appear less severe at first. Families might see:

    • Stiffness in arms and legs (spasticity): Movements may become more rigid over time.

    • Balance and walking issues: Walking may appear unsteady or require support.

    • Involuntary movements and unusual postures (dystonia, choreoathetosis): These may come and go or become more noticeable with age.

    • Learning and attention difficulties: Some children may need extra support with school, focus, or memory.

  • Other Possible Symptoms

    • Hearing or vision loss

    • Speech and language delays

    • Difficulty eating or feeding safely

    • Loss of balance or coordination

    • Decreased mobility or difficulty moving independently

    • Seizures (varying in type and frequency)

  • A brief overview of and general considerations for individuals with TUBB4A-related Leukodystrophy.

    Link to: Children’s Hospital of Philadelphia, Leukodystrophy Center of Excellence Standard of Care

A Note of Hope and Support

It’s important to remember that every child’s experience with H-ABC is different. Some children may walk and talk later than expected. Others may communicate in different ways or need extra support with learning or mobility.

What remains true in every case is that early intervention, family support, and loving care can have a lasting impact. Therapies such as physical, occupational, and speech therapy can help children build skills, maintain comfort, and engage with the world in meaningful ways.

If your child has been diagnosed with H-ABC/TUBB4A, you are not alone. Support is available—for your child, and for you.

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