Overview
Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome, sometimes called HMCC syndrome, is a very rare brain disorder that affects how the nervous system develops. The name describes three main problems seen in the brain: hypomyelination (the protective coating around nerve fibers, called myelin, does not form properly), cerebellar atrophy (the part of the brain that controls balance and coordination is smaller than normal), and hypoplasia of the corpus callosum (the band of nerve fibers connecting the two halves of the brain is underdeveloped). These brain changes cause a range of neurological problems that usually appear in infancy or early childhood. Children with this condition often have significant intellectual disability, delayed development, problems with movement and coordination, and difficulty with speech. Muscle tone is often abnormal, and some children may have seizures. Vision problems and feeding difficulties can also occur. There is currently no cure for HMCC syndrome. Treatment focuses on managing symptoms and supporting development. This includes physical therapy, occupational therapy, speech therapy, anti-seizure medications when needed, and educational support. A team of specialists is usually needed to provide the best care. Early intervention with therapies can help children reach their fullest potential, though the condition is lifelong and causes significant disability.
Key symptoms:
Intellectual disability (difficulty with learning and thinking)Delayed development of motor skills such as sitting, standing, and walkingPoor muscle tone (floppy muscles) or abnormally stiff musclesProblems with balance and coordinationDelayed or absent speechSeizuresInvoluntary eye movements (nystagmus)Vision problemsFeeding difficulties in infancySmall head size (microcephaly) in some casesSpasticity (muscle stiffness that makes movement difficult)
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Infantile
Begins in infancy, roughly 1 month to 2 years old
Treatments
No FDA-approved treatments are currently listed for Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome.
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Specialists
View all specialists →No specialists are currently listed for Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
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Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.Which specific gene change was found, and what does that mean for my child's prognosis?,What therapies should we start right away, and how often should my child receive them?,What signs of seizures should I watch for, and what should I do if one happens?,Are there any clinical trials or research studies that my child might be eligible for?,How will my child's condition change over time — will it stay stable or get worse?,What support services and educational resources are available for my child?,Should other family members be tested for the gene change that caused this condition?
Common questions about Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome
What is Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome?
Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome, sometimes called HMCC syndrome, is a very rare brain disorder that affects how the nervous system develops. The name describes three main problems seen in the brain: hypomyelination (the protective coating around nerve fibers, called myelin, does not form properly), cerebellar atrophy (the part of the brain that controls balance and coordination is smaller than normal), and hypoplasia of the corpus callosum (the band of nerve fibers connecting the two halves of the brain is underdeveloped). These brain changes caus
How is Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome inherited?
Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome typically begin?
Typical onset of Hypomyelination-cerebellar atrophy-hypoplasia of the corpus callosum syndrome is infantile. Age of onset can vary across affected individuals.