Scientific review by: Joshua L. Bonkowsky, MD, PhD, Professor of Pediatrics and Adjunct Professor of Neurology at the University of Utah, and Scientific Advisor to the Foundation to Fight H-ABC.
Noticing that your child is having difficulty with a movement or physical skill they once used can raise understandable questions. Changes in movement can have different causes, and a healthcare professional can help assess what may be happening. This article offers general information and practical steps to help you prepare for that conversation.
What Is Developmental Regression? (In Plain English)
In the medical world, doctors use the term developmental regression when a child loses skills they previously had. It is different from a developmental delay (where a child takes longer to learn a skill). Regression means the skill was there, and now it is fading or gone.
When it comes to motor skills, regression can look like:
A baby who could sit independently suddenly needing to be propped up.
A toddler who was walking confidently reverting to crawling or frequently falling.
A child showing a new shakiness in their hands when reaching for a favorite toy.
Changes in balance, coordination, or muscle tone (limbs feeling unusually stiff or unusually floppy).
Neurological terms can feel like a foreign language, especially when you are operating on survival mode and zero sleep. To understand why this happens, it helps to look at how the brain communicates with the body.
Think of your child’s brain and nervous system as a complex network of electrical wires. For a child to move, walk, or speak, the brain has to send electrical signals down these wires to the muscles. In a typically developing child, these wires are protected by a thick layer of insulation called myelin. This insulation ensures the signals travel fast and clear.
When a child experiences motor regression, it often means something is interfering with those signals, disrupting the insulation, or affecting the areas of the brain that orchestrate smooth movement.
Potential Explanations: Why Does Regression Happen?
There are many reasons why a child might temporarily or progressively lose motor skills. This is why a thorough evaluation by a medical professional is so critical. Broadly speaking, medical teams look into a few primary categories:
1. Temporary or Reversible Factors
Sometimes, regression is a temporary response to an underlying issue. A severe illness, a prolonged hospitalization, unmanaged chronic pain, stress, or even severe sleep disturbances can cause a child to temporarily lose physical stamina or milestones. Once the primary illness or factor is treated, many children regain their footing.
2. Metabolic, Genetic, and Other Health Conditions
The body relies on tiny cellular factories to turn food into energy and clear out cellular waste. If a genetic mutation, or other health problems, changes how these factories work, waste can build up, or the body may fail to produce vital proteins needed for the brain and muscles to function properly.
3. White Matter Disorders (Leukodystrophies)
This is the category closest to our hearts at the foundation. Leukodystrophies are a group of rare genetic conditions that specifically affect the "white matter" of the brain—the myelin insulation we mentioned earlier.
One specific ultra-rare condition under this umbrella is H-ABC (which stands for Hypomyelination with Atrophy of the Basal Ganglia and Cerebellum) aka TUBB4A Related Leukodystrophy.
Hypomyelination simply means the brain was never able to form enough of that protective myelin insulation in the first place.
Atrophy of the Basal Ganglia and Cerebellum means that two specific control centers in the brain responsible for balance, coordination, and smooth muscle movement are shrinking or wearing away over time.
Conditions like H-ABC/TUBB4A are progressive, meaning symptoms change and evolve. A child might be born looking entirely healthy, hitting their early milestones right on time. But as they grow, a tiny mutation in a gene (like the TUBB4A gene) prevents the brain from keeping up with the body's motor demands. Over time, this can cause a gradual loss of the ability to walk, sit up independently, speak clearly, or swallow safely.
An Important Reminder: Reading about rare genetic disorders can make the room spin. Take another breath. Finding a name for what is happening is a journey, and you do not have to arrive at an answer tonight. Your only job right now is to take the very next practical step.
Your Action Plan: What to Do Next
When you are drowning in anxiety, having a concrete checklist can help you regain a sense of control. Here is how you can advocate for your child right now:
1. Document Everything (Build Your "Care Brain")
When you sit down with a specialist, your mind might go blank from stress. Start keeping a dedicated notebook or a digital document.
Write down the timeline: When did you first notice the change? Was it sudden, or did it creep up slowly over weeks?
Take video clips: Doctors find video immensely helpful. Try to safely capture a short clip of the specific behavior or movement that concerns you (e.g., how your child stumbles, holds a cup, or loses balance).
Note any triggers: Did the regression happen right after a high fever, a fall, or a stressful event?
2. Schedule a Medical Evaluation Immediately
Do not wait for your child's next routine wellness checkup. Call your pediatrician and explicitly state: "I am witnessing a regression in my child’s developed motor skills, and I need an urgent evaluation."
Your pediatrician may refer you to a pediatric neurologist—a doctor who specializes in the brain and nervous system. They may recommend tests such as blood work, genetic screening, or an MRI, which takes a detailed picture of the brain's structure and its white matter insulation.
3. Request General Support Therapies Early
You do not need a final, definitive diagnosis to begin supporting your child’s physical body. Ask your doctor for referrals to:
Physical Therapy (PT): To focus on gross motor skills, balance, and safely maintaining strength.
Occupational Therapy (OT): To help with fine motor skills, like feeding, writing, and daily tasks.
Speech-Language Pathology (SLP): To evaluate and support communication and safe swallowing if you notice any changes in how your child eats or speaks.
Holding Space for the Lived Reality
We promised you no empty hype or toxic positivity. The truth is, entering the world of diagnostic odysseys, neurological tests, and medical uncertainty is exhausting. It strains finances, fractures sleep, and requires a level of daily vigilance that feels impossible to sustain.
If your child is eventually diagnosed with a rare neurodegenerative condition like H-ABC, life will look vastly different than the one you originally imagined. There will be hard choices, adaptive equipment to navigate, and deep grief to process.
But there is also an absolute truth to these stories that we honor every day: Your child is a person first, not a list of medical symptoms. Children living with complex neurological conditions continue to laugh at silly jokes, feel fierce love, celebrate ordinary moments of joy, and teach the world around them profound lessons about resilience.
You do not have to carry the weight of the entire medical system on your shoulders tonight. You do not have to fix this in the next hour. Focus entirely on your child, protect your energy, and take things one single phone call, one single appointment, and one single breath at a time.
Please Note!
This article is for informational purposes and intended to provide general educational guidance and emotional support during an acute crisis. The Foundation to Fight H-ABC does not provide medical advice. Every child's biology is unique. If you are witnessing developmental or motor regression in your child, please contact your pediatrician or care provider immediately to seek personalized clinical guidance.