Overview
Synpolydactyly type 3 (SPD3) is a rare inherited condition that affects the development of the hands and feet before birth. It belongs to a group of limb malformations called synpolydactyly, where fingers or toes are both fused together (syndactyly) and extra digits are present (polydactyly). In type 3 specifically, the condition typically involves fusion of the fourth and fifth fingers (ring and little fingers) along with the presence of extra fingers. The feet may also be affected, with fusion between toes. The severity can vary even among members of the same family — some people may have mild webbing between fingers, while others may have more complex bony fusions or additional digits. Synpolydactyly type 3 is present at birth and is usually noticed right away during a newborn examination. The condition primarily affects the structure and function of the hands and feet but does not typically involve other organ systems. Intelligence and overall health are usually normal. Treatment is mainly surgical. Orthopedic or plastic surgeons who specialize in hand surgery can separate fused fingers and remove extra digits to improve hand function and appearance. Surgery is often performed in early childhood to allow for better hand development. Physical therapy and occupational therapy may be recommended after surgery to help with hand strength and fine motor skills. While there is no cure that addresses the underlying genetic cause, surgical outcomes are generally good, and most individuals lead fully independent lives.
Key symptoms:
Fused fingers, especially the ring and little fingersExtra fingers on one or both handsWebbing between fingersFused toesExtra toesAbnormal shape or shortening of affected fingersReduced range of motion in affected fingersDifficulty with fine motor tasks like gripping or writingAbnormal appearance of fingernails on affected digitsBony fusion between finger bones
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 Synpolydactyly type 3.
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View all trials with filters →No actively recruiting trials found for Synpolydactyly type 3 at this time.
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Specialists
View all specialists →No specialists are currently listed for Synpolydactyly type 3.
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 Synpolydactyly type 3.
Community
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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.How severe is my child's synpolydactyly, and which fingers or toes are affected?,When is the best age to have surgery, and how many surgeries might be needed?,What are the risks and expected outcomes of surgery?,Will my child need occupational therapy after surgery, and for how long?,Should we pursue genetic testing to confirm the diagnosis?,What is the chance of passing this condition to future children?,Are there any specialists or centers with particular expertise in this condition?
Common questions about Synpolydactyly type 3
What is Synpolydactyly type 3?
Synpolydactyly type 3 (SPD3) is a rare inherited condition that affects the development of the hands and feet before birth. It belongs to a group of limb malformations called synpolydactyly, where fingers or toes are both fused together (syndactyly) and extra digits are present (polydactyly). In type 3 specifically, the condition typically involves fusion of the fourth and fifth fingers (ring and little fingers) along with the presence of extra fingers. The feet may also be affected, with fusion between toes. The severity can vary even among members of the same family — some people may have mi
How is Synpolydactyly type 3 inherited?
Synpolydactyly type 3 follows a autosomal dominant inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Synpolydactyly type 3 typically begin?
Typical onset of Synpolydactyly type 3 is neonatal. Age of onset can vary across affected individuals.