Overview
Congenital myopathy with myasthenic-like onset is a rare inherited muscle disease that is present from birth or becomes noticeable in early infancy. The name reflects two key features: it is a congenital myopathy (meaning a muscle disorder that starts before or at birth) and it has symptoms that look similar to myasthenia gravis, a condition where the connection between nerves and muscles does not work properly. This disease is caused by changes (mutations) in the SNAP25 gene, which plays an important role in how nerve signals are sent to muscles. People with this condition typically experience significant muscle weakness from birth or very early in life. The weakness often affects the muscles needed for breathing, swallowing, and moving the limbs. Babies may have very low muscle tone (called hypotonia or 'floppy baby' syndrome), feeding difficulties, and may need breathing support. Eye muscle weakness causing drooping eyelids (ptosis) or abnormal eye movements can also occur. There is currently no cure for this condition. Treatment focuses on managing symptoms and supporting quality of life. Some patients may benefit from medications used to treat myasthenia gravis, such as acetylcholinesterase inhibitors, though responses vary. Respiratory support, physical therapy, occupational therapy, and speech therapy are important parts of care. Because this is an extremely rare condition, management is highly individualized and guided by specialists in neuromuscular disease.
Key symptoms:
Severe muscle weakness from birth or early infancyVery low muscle tone ('floppy baby')Difficulty breathing, sometimes requiring a ventilatorFeeding difficulties and trouble swallowingDrooping eyelids (ptosis)Abnormal or limited eye movementsWeakness that may fluctuate or worsen with activityDelayed motor milestones such as sitting or walkingWeak cry in newbornsReduced facial expressions due to facial muscle weakness
Clinical phenotype terms (25)— hover any for plain English
Autosomal dominant
Passed on from just one parent; each child has about a 50% chance of inheriting it
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Congenital myopathy with myasthenic-like onset.
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Specialists
View all specialists →No specialists are currently listed for Congenital myopathy with myasthenic-like onset.
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 Congenital myopathy with myasthenic-like onset.
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Caregiver Resources
NORD Caregiver Resources
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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.What specific mutation was found in the SNAP25 gene, and what does it mean for my child's prognosis?,Should other family members be tested for this genetic change?,Is my child a candidate for treatment with pyridostigmine or other myasthenia-type medications?,What signs should prompt me to seek emergency care, and what should I tell emergency doctors?,What therapies (physical, occupational, speech) are recommended, and how often should they occur?,Are there any clinical trials or research studies we should consider enrolling in?,What respiratory monitoring does my child need, and at what point might breathing support be required?
Common questions about Congenital myopathy with myasthenic-like onset
What is Congenital myopathy with myasthenic-like onset?
Congenital myopathy with myasthenic-like onset is a rare inherited muscle disease that is present from birth or becomes noticeable in early infancy. The name reflects two key features: it is a congenital myopathy (meaning a muscle disorder that starts before or at birth) and it has symptoms that look similar to myasthenia gravis, a condition where the connection between nerves and muscles does not work properly. This disease is caused by changes (mutations) in the SNAP25 gene, which plays an important role in how nerve signals are sent to muscles. People with this condition typically experien
How is Congenital myopathy with myasthenic-like onset inherited?
Congenital myopathy with myasthenic-like onset follows a autosomal dominant inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Congenital myopathy with myasthenic-like onset typically begin?
Typical onset of Congenital myopathy with myasthenic-like onset is neonatal. Age of onset can vary across affected individuals.