Overview
Classic organic aciduria (Orphanet code 79163) is a broad term used to describe a group of inherited metabolic disorders where the body cannot properly break down certain proteins and fats. This leads to a buildup of harmful acids — called organic acids — in the blood and urine. The most well-known conditions in this group include propionic acidemia, methylmalonic acidemia, isovaleric acidemia, and glutaric aciduria type 1. These conditions are caused by missing or poorly working enzymes that are needed to process specific amino acids (the building blocks of protein). When these acids build up, they can damage many organs, especially the brain, liver, heart, and kidneys. Symptoms often appear in the first days or weeks of life and can include vomiting, poor feeding, extreme tiredness, and a dangerous buildup of acid in the blood called metabolic acidosis. Without quick treatment, these episodes can cause brain damage or be life-threatening. Treatment focuses on preventing dangerous episodes through a carefully managed low-protein diet, special medical formulas, vitamins like biotin or B12 (depending on the specific type), and sometimes medications to help remove harmful substances from the body. Some patients may eventually need an organ transplant. With early diagnosis — often through newborn screening — and careful ongoing management, many children can live meaningful lives, though long-term complications remain a serious concern.
Key symptoms:
Vomiting, especially in newborns or during illnessPoor feeding and difficulty gaining weightExtreme tiredness or low energy (lethargy)Unusual or fruity-smelling urine or breathIntellectual disability or developmental delaysMuscle weakness or low muscle tone (floppiness)SeizuresMovement problems such as involuntary muscle spasms (dystonia)Enlarged liverAnemia (low red blood cell count)Weakened immune system leading to frequent infectionsHeart muscle problems (cardiomyopathy) in some typesKidney damage over time in some typesPancreatitis (inflammation of the pancreas)Episodes of metabolic crisis triggered by illness, fasting, or high protein intake
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 Classic organic aciduria.
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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 Classic organic aciduria.
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.Which specific type of organic aciduria does my child have, and what gene is affected?,What are the early warning signs of a metabolic crisis, and exactly what should I do if one happens?,How strict does the low-protein diet need to be, and can a dietitian help us plan meals?,Are there any vitamin supplements or medications that could help my child's specific condition?,Should we consider organ transplantation, and if so, when and what are the risks and benefits?,What long-term complications should we watch for, and how often should my child be monitored?,Are there any clinical trials or new treatments we should know about?
Common questions about Classic organic aciduria
What is Classic organic aciduria?
Classic organic aciduria (Orphanet code 79163) is a broad term used to describe a group of inherited metabolic disorders where the body cannot properly break down certain proteins and fats. This leads to a buildup of harmful acids — called organic acids — in the blood and urine. The most well-known conditions in this group include propionic acidemia, methylmalonic acidemia, isovaleric acidemia, and glutaric aciduria type 1. These conditions are caused by missing or poorly working enzymes that are needed to process specific amino acids (the building blocks of protein). When these acids build u
How is Classic organic aciduria inherited?
Classic organic aciduria follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Classic organic aciduria typically begin?
Typical onset of Classic organic aciduria is neonatal. Age of onset can vary across affected individuals.