Overview
Congenital amyoplasia is a rare condition present from birth in which a baby is born with very little or no muscle development in parts of the body. The name comes from Greek words meaning 'without muscle formation.' It is considered the most common and classic form of a broader group of conditions called arthrogryposis multiplex congenita (AMC), which means multiple stiff joints present at birth. In congenital amyoplasia, the muscles — most often in the arms and legs — fail to develop normally before birth, leaving them thin, weak, or replaced by fatty or fibrous tissue. This leads to joints that are fixed in unusual positions and have very limited movement. Babies born with this condition typically have arms that are rotated inward with stiff elbows and wrists, and legs that may be affected by hip dislocations, clubfoot, or knee problems. The face and spine are usually not affected, and intelligence is completely normal. The exact cause is not fully understood, but it is believed to result from reduced fetal movement in the womb, possibly due to reduced blood flow to the developing baby's muscles during pregnancy. Treatment focuses on improving function and mobility. This includes physical therapy, occupational therapy, splinting, casting, and sometimes surgery to correct joint positions. With early and consistent treatment, many people with congenital amyoplasia can achieve meaningful independence and lead fulfilling lives. There is no cure, but supportive care can make a significant difference in quality of life.
Also known as:
Key symptoms:
Very weak or absent muscles in the arms and/or legsJoints that are stiff and fixed in unusual positions from birthArms rotated inward with elbows that cannot fully bendWrists bent downward and fingers that are stiffClubfoot (feet turned inward or downward)Hip dislocation or hip joints that are out of placeKnees that are either very bent or locked straightThin limbs due to lack of muscle bulkDimples or skin creases over affected jointsNormal intelligence and facial appearanceNormal spine in most casesReduced ability to move arms and legs independently
Sporadic
Usually appears on its own, not inherited from a parent
Neonatal
Begins at or shortly after birth (first 4 weeks)
FDA & Trial Timeline
2 eventsNemours Children's Clinic — NA
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
1 availableAminocaproic Acid
acute and life-threatening abruptio placentae
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 amyoplasia.
Community
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Start the conversation →Latest news about Congenital amyoplasia
Disease timeline:
New recruiting trial: Impact Study on Users of Upper Limb Assistive Devices
A new clinical trial is recruiting patients for Congenital amyoplasia
Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
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 joints and muscles are most affected in my child, and what does that mean for their development?,What therapies should we start right away, and how often should they happen?,Will my child need surgery, and if so, when is the best time?,What can we do at home to support my child's progress between therapy sessions?,What level of independence can we realistically hope for as my child grows up?,Are there any other conditions we should test for that can look like congenital amyoplasia?,What support services or patient organizations can help our family?
Common questions about Congenital amyoplasia
What is Congenital amyoplasia?
Congenital amyoplasia is a rare condition present from birth in which a baby is born with very little or no muscle development in parts of the body. The name comes from Greek words meaning 'without muscle formation.' It is considered the most common and classic form of a broader group of conditions called arthrogryposis multiplex congenita (AMC), which means multiple stiff joints present at birth. In congenital amyoplasia, the muscles — most often in the arms and legs — fail to develop normally before birth, leaving them thin, weak, or replaced by fatty or fibrous tissue. This leads to joints
How is Congenital amyoplasia inherited?
Congenital amyoplasia follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Congenital amyoplasia typically begin?
Typical onset of Congenital amyoplasia is neonatal. Age of onset can vary across affected individuals.
Are there clinical trials for Congenital amyoplasia?
Yes — 1 recruiting clinical trial is currently listed for Congenital amyoplasia on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.
Which specialists treat Congenital amyoplasia?
3 specialists and care centers treating Congenital amyoplasia are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.