Overview
Spondylometaphyseal dysplasia, A4 type (also called SMD type A4) is an extremely rare genetic bone disorder that affects the development of the spine and the ends of long bones (called metaphyses). It belongs to a group of skeletal conditions known as spondylometaphyseal dysplasias, which share features of abnormal vertebrae (bones of the spine) and abnormal growth areas near the ends of long bones. Children with this condition typically present with short stature, skeletal abnormalities visible on X-rays, and changes in the shape of their vertebrae (platyspondyly). The metaphyses of the long bones — the areas near the growth plates in the arms and legs — may appear widened or irregular on imaging. Because this is such a rare condition, the full range of symptoms and the natural history are not completely understood. Affected individuals may experience limb shortening, waddling gait, and joint problems. Some patients may also develop curvature of the spine (scoliosis or kyphosis). Growth is often significantly below average. There is currently no cure for this condition, and treatment focuses on managing symptoms, supporting mobility, and monitoring skeletal development over time. Orthopedic care, physical therapy, and regular follow-up with specialists are the main pillars of management. Genetic counseling is recommended for affected families to understand the inheritance pattern and recurrence risk.
Key symptoms:
Short statureShort limbs relative to the trunkAbnormal shape of the vertebrae (flattened spine bones)Widened or irregular ends of long bonesWaddling gaitBowed legs or knock kneesCurvature of the spine (scoliosis or kyphosis)Joint stiffness or limited range of motionDelayed motor milestones such as walkingBack pain or leg pain
Clinical phenotype terms (8)— 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 Spondylometaphyseal dysplasia, A4 type.
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Specialists
View all specialists →No specialists are currently listed for Spondylometaphyseal dysplasia, A4 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 Spondylometaphyseal dysplasia, A4 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
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.What specific type of spondylometaphyseal dysplasia does my child have, and how was it confirmed?,What skeletal complications should I watch for as my child grows?,How often should we have X-rays or other imaging done?,Is genetic testing available to identify the exact gene involved?,What physical therapy or exercises are recommended to support mobility?,Are there any clinical trials or research studies we could participate in?,Should other family members be tested or evaluated?
Common questions about Spondylometaphyseal dysplasia, A4 type
What is Spondylometaphyseal dysplasia, A4 type?
Spondylometaphyseal dysplasia, A4 type (also called SMD type A4) is an extremely rare genetic bone disorder that affects the development of the spine and the ends of long bones (called metaphyses). It belongs to a group of skeletal conditions known as spondylometaphyseal dysplasias, which share features of abnormal vertebrae (bones of the spine) and abnormal growth areas near the ends of long bones. Children with this condition typically present with short stature, skeletal abnormalities visible on X-rays, and changes in the shape of their vertebrae (platyspondyly). The metaphyses of the long
How is Spondylometaphyseal dysplasia, A4 type inherited?
Spondylometaphyseal dysplasia, A4 type follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Spondylometaphyseal dysplasia, A4 type typically begin?
Typical onset of Spondylometaphyseal dysplasia, A4 type is childhood. Age of onset can vary across affected individuals.