Overview
Non-syndromic limb overgrowth is a rare condition in which one or more limbs grow larger than normal without other body systems being affected. The term 'non-syndromic' means that the overgrowth happens on its own and is not part of a broader syndrome that involves other organs or developmental differences. The overgrowth can affect bones, soft tissues, or both, leading to a noticeable difference in size between the affected limb and the rest of the body. This condition is sometimes also referred to as isolated limb overgrowth or isolated hemihyperplasia when it affects one side of the body. Symptoms typically become apparent at birth or during early childhood as the affected limb grows faster or larger than expected. The degree of overgrowth can range from mild, barely noticeable differences to significant asymmetry that affects walking, posture, and daily activities. In some cases, the leg length difference can cause back pain or gait problems over time. Treatment depends on the severity of the overgrowth. Mild cases may only need monitoring, while more significant differences may require orthopedic interventions such as shoe lifts, epiphysiodesis (a procedure to slow growth in the longer limb), or other surgical corrections. Physical therapy can also help with mobility and strength. Because some forms of limb overgrowth carry a slightly increased risk of certain tumors, regular screening may be recommended. The condition is not life-threatening, but ongoing management is important for quality of life.
Key symptoms:
One arm or leg noticeably larger than the otherUnequal leg lengthsAsymmetry in limb circumference or girthDifficulty walking or abnormal gaitBack pain due to leg length differenceEnlarged fingers or toes on the affected limbScoliosis or spinal curvature from uneven leg lengthsSoft tissue swelling in the affected limbIncreased bone length on one sideShoe fitting problems due to foot size differenceJoint pain or discomfort in the affected limb
Variable
Can be inherited in different ways depending on the underlying gene
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Non-syndromic limb overgrowth.
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Specialists
View all specialists →No specialists are currently listed for Non-syndromic limb overgrowth.
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 Non-syndromic limb overgrowth.
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.How severe is the limb overgrowth, and is it expected to get worse as my child grows?,Should we pursue genetic testing, and if so, what type of testing is recommended?,Does my child need tumor screening, and how often should it be done?,What treatment options are available now, and when might surgery be considered?,Are there any clinical trials or emerging therapies that might be appropriate?,How can we best support my child's mobility and physical development?,Should we be concerned about any other health complications related to this condition?
Common questions about Non-syndromic limb overgrowth
What is Non-syndromic limb overgrowth?
Non-syndromic limb overgrowth is a rare condition in which one or more limbs grow larger than normal without other body systems being affected. The term 'non-syndromic' means that the overgrowth happens on its own and is not part of a broader syndrome that involves other organs or developmental differences. The overgrowth can affect bones, soft tissues, or both, leading to a noticeable difference in size between the affected limb and the rest of the body. This condition is sometimes also referred to as isolated limb overgrowth or isolated hemihyperplasia when it affects one side of the body.
At what age does Non-syndromic limb overgrowth typically begin?
Typical onset of Non-syndromic limb overgrowth is neonatal. Age of onset can vary across affected individuals.