Overview
Seizures-intellectual disability due to hydroxylysinuria syndrome (also sometimes called hydroxylysinuria) is an extremely rare inherited metabolic disorder. It affects how the body breaks down a building block of protein called hydroxylysine. When this process does not work properly, hydroxylysine builds up in the blood and spills into the urine. This buildup appears to interfere with normal brain development and function. The main features of this condition include recurring seizures (epilepsy) and intellectual disability, meaning that learning, memory, and daily problem-solving are harder than usual. Some people may also have delays in reaching developmental milestones like talking or walking. The exact reason why too much hydroxylysine harms the brain is not fully understood, and research into this condition is still very limited because so few cases have ever been reported. Treatment is focused on managing symptoms rather than fixing the underlying cause. Seizures are typically treated with anti-epileptic medications. There is currently no cure, and no specific diet or drug has been proven to lower hydroxylysine levels effectively. People with this condition benefit from a team of specialists including neurologists, metabolic geneticists, and developmental therapists who work together to support quality of life.
Key symptoms:
Recurring seizures (epilepsy)Intellectual disability (difficulty with learning and thinking)Delayed speech and language developmentDelayed motor milestones such as sitting or walkingElevated hydroxylysine levels in the urineElevated hydroxylysine levels in the bloodBehavioral difficulties
Clinical phenotype terms (3)— hover any for plain English
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Infantile
Begins in infancy, roughly 1 month to 2 years old
Treatments
No FDA-approved treatments are currently listed for Seizures-intellectual disability due to hydroxylysinuria syndrome.
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Specialists
View all specialists →No specialists are currently listed for Seizures-intellectual disability due to hydroxylysinuria syndrome.
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 Seizures-intellectual disability due to hydroxylysinuria syndrome.
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Caregiver Resources
NORD Caregiver Resources
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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 type of genetic testing should we do to confirm the diagnosis and identify the gene involved?,Which anti-epileptic medication is the best starting choice for my child's type of seizures?,What should we do if a seizure lasts longer than 5 minutes — do we need a rescue medication at home?,Are there any dietary changes or supplements that might help manage hydroxylysine levels?,What therapies (speech, occupational, physical) should we start, and how soon?,Are there any research studies or patient registries we can join to help advance understanding of this condition?,What signs of worsening should prompt us to seek urgent medical attention?
Common questions about Seizures-intellectual disability due to hydroxylysinuria syndrome
What is Seizures-intellectual disability due to hydroxylysinuria syndrome?
Seizures-intellectual disability due to hydroxylysinuria syndrome (also sometimes called hydroxylysinuria) is an extremely rare inherited metabolic disorder. It affects how the body breaks down a building block of protein called hydroxylysine. When this process does not work properly, hydroxylysine builds up in the blood and spills into the urine. This buildup appears to interfere with normal brain development and function. The main features of this condition include recurring seizures (epilepsy) and intellectual disability, meaning that learning, memory, and daily problem-solving are harder
How is Seizures-intellectual disability due to hydroxylysinuria syndrome inherited?
Seizures-intellectual disability due to hydroxylysinuria syndrome follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Seizures-intellectual disability due to hydroxylysinuria syndrome typically begin?
Typical onset of Seizures-intellectual disability due to hydroxylysinuria syndrome is infantile. Age of onset can vary across affected individuals.