Overview
Autosomal recessive spastic paraplegia type 9B (also called SPG9B or AR-SPG9) is a rare inherited neurological condition that belongs to a large group of disorders known as hereditary spastic paraplegias (HSPs). These conditions share a common feature: progressive stiffness and weakness in the legs caused by damage to the long nerve fibers that run from the brain down the spinal cord. In SPG9B specifically, mutations in the ALDH18A1 gene disrupt the normal function of an enzyme involved in making certain amino acids, which leads to nerve cell damage over time. People with SPG9B typically experience gradually worsening leg stiffness (spasticity), difficulty walking, and muscle weakness. Some individuals also develop intellectual disability, cataracts (clouding of the eye lens), and other neurological features, making this a more complex or 'complicated' form of hereditary spastic paraplegia. Symptoms often begin in childhood or early adulthood, though the age of onset can vary. There is currently no cure for SPG9B. Treatment focuses on managing symptoms, improving quality of life, and maintaining mobility for as long as possible. Physical therapy, muscle relaxant medications, and assistive devices are the main tools used today. Research into this condition is ongoing, and genetic diagnosis is increasingly important for families.
Also known as:
Key symptoms:
Progressive leg stiffness (spasticity)Leg muscle weaknessDifficulty walking or abnormal gaitIntellectual disability or learning difficultiesCataracts (cloudy lenses in the eyes)Muscle wasting (atrophy)Exaggerated reflexes in the legsBladder control problemsFoot deformities such as high arches (pes cavus)Delayed developmental milestones in childhoodSpeech difficulties in some individualsBalance and coordination problems
Clinical phenotype terms (29)— hover any for plain English
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Variable
Can begin at different ages, from infancy through adulthood
Treatments
No FDA-approved treatments are currently listed for Autosomal recessive spastic paraplegia type 9B.
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Specialists
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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 Autosomal recessive spastic paraplegia type 9B.
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 mutation was found in the ALDH18A1 gene, and what does it mean for my (or my child's) prognosis?,Should other family members be tested, and what are the chances of siblings being affected?,What physical therapy program do you recommend, and how often should we attend?,Are there any clinical trials or research studies we could participate in?,What signs of progression should prompt us to contact you urgently?,How should we manage spasticity, and what are the options if current medications stop working?,Are there any specialists — such as an ophthalmologist or urologist — we should see regularly alongside you?
Common questions about Autosomal recessive spastic paraplegia type 9B
What is Autosomal recessive spastic paraplegia type 9B?
Autosomal recessive spastic paraplegia type 9B (also called SPG9B or AR-SPG9) is a rare inherited neurological condition that belongs to a large group of disorders known as hereditary spastic paraplegias (HSPs). These conditions share a common feature: progressive stiffness and weakness in the legs caused by damage to the long nerve fibers that run from the brain down the spinal cord. In SPG9B specifically, mutations in the ALDH18A1 gene disrupt the normal function of an enzyme involved in making certain amino acids, which leads to nerve cell damage over time. People with SPG9B typically expe
How is Autosomal recessive spastic paraplegia type 9B inherited?
Autosomal recessive spastic paraplegia type 9B follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.