Overview
Congenital absence or hypoplasia (underdevelopment) of the thumb on both hands is a rare condition present at birth where a baby is born with both thumbs either missing entirely or significantly smaller and less developed than normal. This condition is sometimes called bilateral thumb aplasia or bilateral thumb hypoplasia. Because the entry is marked as 'OBSOLETE' in Orphanet, it means this specific classification is no longer actively used and has likely been reclassified under broader categories of limb malformations or radial ray deficiencies. The thumbs play a critical role in hand function, especially for gripping and pinching. When both thumbs are affected, children may have significant difficulty with everyday tasks such as grasping objects, writing, buttoning clothes, and feeding themselves. The severity can range from a slightly small but functional thumb to a completely absent thumb. This condition can occur as an isolated finding or as part of a broader syndrome, such as Holt-Oram syndrome, Fanconi anemia, thrombocytopenia-absent radius (TAR) syndrome, or VACTERL association. Treatment depends on the severity and may include surgical reconstruction of the thumb, pollicization (surgically converting the index finger into a thumb), or use of adaptive devices. Early evaluation by a hand surgeon and geneticist is important to determine the underlying cause and plan appropriate treatment.
Key symptoms:
Missing thumbs on both hands at birthVery small or underdeveloped thumbs on both handsDifficulty gripping or holding objectsWeak pinch strengthTrouble with fine motor tasks like writing or buttoningShortened or absent forearm bone (radius) in some casesPossible abnormalities of the wrist bonesFloppy or unstable thumb joint if thumb is present but underdevelopedDifficulty feeding independently as a toddlerPossible associated heart defects depending on underlying syndromePossible low blood counts if associated with Fanconi anemia
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 OBSOLETE: Congenital absence/hypoplasia of thumb, bilateral.
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Specialists
View all specialists →No specialists are currently listed for OBSOLETE: Congenital absence/hypoplasia of thumb, bilateral.
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 OBSOLETE: Congenital absence/hypoplasia of thumb, bilateral.
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.Is my child's thumb condition isolated or part of a larger syndrome?,What genetic tests should be done to find the underlying cause?,Is pollicization surgery recommended, and at what age should it be done?,What hand function can we expect after surgery and therapy?,Are there any associated health problems we need to screen for, such as heart defects or blood disorders?,Should other family members be tested or evaluated?,What adaptive tools or therapies can help my child in the meantime?
Common questions about OBSOLETE: Congenital absence/hypoplasia of thumb, bilateral
What is OBSOLETE: Congenital absence/hypoplasia of thumb, bilateral?
Congenital absence or hypoplasia (underdevelopment) of the thumb on both hands is a rare condition present at birth where a baby is born with both thumbs either missing entirely or significantly smaller and less developed than normal. This condition is sometimes called bilateral thumb aplasia or bilateral thumb hypoplasia. Because the entry is marked as 'OBSOLETE' in Orphanet, it means this specific classification is no longer actively used and has likely been reclassified under broader categories of limb malformations or radial ray deficiencies. The thumbs play a critical role in hand functi
At what age does OBSOLETE: Congenital absence/hypoplasia of thumb, bilateral typically begin?
Typical onset of OBSOLETE: Congenital absence/hypoplasia of thumb, bilateral is neonatal. Age of onset can vary across affected individuals.