Overview
Spondyloepiphyseal dysplasia tarda, Kohn type (also called SED tarda, Kohn type) is an extremely rare inherited bone disorder that belongs to a group of conditions known as skeletal dysplasias. These are conditions where the bones and cartilage do not develop properly. In this specific type, the spine (spondylo-) and the ends of the long bones near the joints (epiphyses) are primarily affected, but the symptoms tend to appear later in childhood rather than at birth — which is what "tarda" means (late onset). People with this condition typically develop short stature, particularly a short trunk relative to their limbs. The spine may show flattened vertebrae (platyspondyly) visible on X-rays, and the joints can become stiff or painful over time. Progressive joint problems, especially in the hips, knees, and spine, are common and may lead to early-onset arthritis. Some individuals may also develop a barrel-shaped chest or mild curvature of the spine. Because this is such a rare condition, treatment is mainly supportive and focused on managing symptoms. There is no cure, but orthopedic care, physical therapy, and pain management can help maintain mobility and quality of life. Regular monitoring by specialists is important to track bone and joint changes over time. Surgery may sometimes be needed for severe joint or spinal problems.
Key symptoms:
Short stature with a short trunkFlattened spinal vertebrae visible on X-rayJoint stiffness and limited range of motionEarly-onset arthritis, especially in the hipsBack painBarrel-shaped or broad chestMild curvature of the spine (scoliosis or kyphosis)Waddling gait or difficulty walkingHip pain or hip joint problemsKnee pain or swellingDelayed growth during childhood
Clinical phenotype terms (11)— hover any for plain English
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Childhood
Begins in childhood, roughly ages 1 to 12
Treatments
No FDA-approved treatments are currently listed for Spondyloepiphyseal dysplasia tarda, Kohn type.
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Specialists
View all specialists →No specialists are currently listed for Spondyloepiphyseal dysplasia tarda, Kohn type.
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 Spondyloepiphyseal dysplasia tarda, Kohn type.
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.What specific type of spondyloepiphyseal dysplasia does my child have, and how was it confirmed?,Should we pursue genetic testing, and what might it tell us?,What kind of physical therapy or exercise program would be most helpful?,How often should we have X-rays or other imaging to monitor bone and joint changes?,What signs should prompt us to seek urgent medical attention?,Are there any activities or sports that should be avoided to protect the joints and spine?,What are the options if joint problems become severe — would surgery be considered?
Common questions about Spondyloepiphyseal dysplasia tarda, Kohn type
What is Spondyloepiphyseal dysplasia tarda, Kohn type?
Spondyloepiphyseal dysplasia tarda, Kohn type (also called SED tarda, Kohn type) is an extremely rare inherited bone disorder that belongs to a group of conditions known as skeletal dysplasias. These are conditions where the bones and cartilage do not develop properly. In this specific type, the spine (spondylo-) and the ends of the long bones near the joints (epiphyses) are primarily affected, but the symptoms tend to appear later in childhood rather than at birth — which is what "tarda" means (late onset). People with this condition typically develop short stature, particularly a short trun
How is Spondyloepiphyseal dysplasia tarda, Kohn type inherited?
Spondyloepiphyseal dysplasia tarda, Kohn type follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Spondyloepiphyseal dysplasia tarda, Kohn type typically begin?
Typical onset of Spondyloepiphyseal dysplasia tarda, Kohn type is childhood. Age of onset can vary across affected individuals.