Overview
Iminoglycinuria (also called familial iminoglycinuria) is a rare inherited condition that affects how the kidneys handle certain amino acids — the building blocks of protein. Normally, the kidneys filter the blood and then reabsorb useful substances back into the body. In iminoglycinuria, the kidneys cannot properly reabsorb three specific amino acids: proline, hydroxyproline, and glycine. As a result, these amino acids spill into the urine in larger-than-normal amounts. The condition is caused by changes (variants) in genes that control special transport proteins in the kidney. One of the most important things to understand about iminoglycinuria is that it is generally considered a benign condition, meaning it does not usually cause health problems on its own. Most people with iminoglycinuria live completely normal, healthy lives and never experience symptoms directly caused by the condition. It is often discovered by accident during routine urine testing done for other reasons. Because it is so rarely harmful, many doctors consider it more of a biochemical trait than a true disease. There is no specific treatment needed for most people with iminoglycinuria, and no special diet is required. The main importance of diagnosing this condition is to avoid unnecessary worry or further invasive testing, and to allow genetic counseling for families who want to understand the risk of passing it on to children. Ongoing research continues to clarify which gene changes are responsible and whether any rare cases might have associated health concerns.
Key symptoms:
Excess proline in the urine (usually found on routine testing)Excess hydroxyproline in the urineExcess glycine in the urineNo physical symptoms in most casesOccasionally discovered alongside other unrelated health investigations
Clinical phenotype terms (6)
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Iminoglycinuria.
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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 Iminoglycinuria.
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Caregiver Resources
NORD Caregiver Resources
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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.Does my child's iminoglycinuria require any treatment or dietary changes?,Should other family members be tested for this condition?,What is the chance that my future children will have iminoglycinuria?,Are there any long-term health risks I should watch for?,Do I need to tell other doctors or specialists about this diagnosis?,Is there any reason to repeat urine or blood tests over time?,Are there any research studies or registries I should know about?
Common questions about Iminoglycinuria
What is Iminoglycinuria?
Iminoglycinuria (also called familial iminoglycinuria) is a rare inherited condition that affects how the kidneys handle certain amino acids — the building blocks of protein. Normally, the kidneys filter the blood and then reabsorb useful substances back into the body. In iminoglycinuria, the kidneys cannot properly reabsorb three specific amino acids: proline, hydroxyproline, and glycine. As a result, these amino acids spill into the urine in larger-than-normal amounts. The condition is caused by changes (variants) in genes that control special transport proteins in the kidney. One of the mo
How is Iminoglycinuria inherited?
Iminoglycinuria follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Iminoglycinuria typically begin?
Typical onset of Iminoglycinuria is neonatal. Age of onset can vary across affected individuals.