Glutaric Acidemia Type I
Glutaric Acidemia Type I
Also known as:GA-1, Glutaric aciduria type I, GCDH deficiency, Glutaric aciduria type 1
Glutaric acidemia type I is an organic acid metabolism disorder that can cause acute brain injury and movement problems in infants and young children after infections or fasting if not identified in time.
Start Here
A quick guide to the next step: which department to start with, what to prepare, and what to ask.
When newborn screening is positive, infants have enlarged head circumference, developmental regression, abnormal muscle tone, or sudden movement problems after infection or fasting, seek care promptly at a metabolic genetics clinic, pediatric neurology, or neonatal/pediatric emergency department.
Insufficient GCDH enzyme function affects the metabolism of lysine, hydroxylysine, and tryptophan. Accumulated metabolites can increase the risk of brain injury, especially in the basal ganglia.
Yes, there are management plans from metabolic specialists. Key points include early identification, nutrition and metabolic management, emergency protocols during infection or fasting, and long-term neurodevelopmental follow-up.
Yes, usually autosomal recessive, related to biallelic pathogenic variants in GCDH.
Early signs may only include enlarged head or mild developmental clues; acute episodes are often mistaken for common infections, seizures, or encephalitis. Without combining newborn screening results and organic acid testing, the window may be missed.
This page helps patients and families organize care leads. It does not replace a clinician’s diagnosis or treatment plan. For testing, medication, referrals, emergency care, and support applications, follow qualified clinicians, medical institutions, support organizations, and official sources.
Diagnosis Path
Organized around the practical patient journey: identify clues, avoid common delays, then prepare for care.
When to Suspect It
- Newborn screening suggests abnormal C5DC or related organic acid metabolism.
- Infant has an enlarged or rapidly growing head circumference, especially with developmental delay or abnormal muscle tone.
- After infection, fever, vomiting, fasting, or surgery, symptoms like drowsiness, poor feeding, developmental regression, or abnormal movements appear.
- Brain MRI shows basal ganglia injury, widened frontotemporal CSF spaces, or imaging findings consistent with GA-1.
- Family history of GA-1, infant acute encephalopathy, movement disorders, or consanguinity.
Common Wrong Turns
- Not following up with metabolic specialist after a positive screening result.
- Attributing enlarged head solely to familial factors without considering metabolic disease or MRI findings.
- During acute episodes, treating only for infection or encephalitis without starting metabolic crisis evaluation.
- After diagnosis, lacking a written emergency plan for illness or fasting, leading to repeated risks during infections.
Departments to Start With
- Metabolic Genetics / Medical Genetics
- Neonatology / Pediatric Emergency
- Pediatric Neurology
- Nutrition (under metabolic specialist guidance)
- Rehabilitation Medicine (for movement disorders or developmental issues)
Before the Visit
- Keep records of newborn screening, follow-up notifications, blood acylcarnitine, urine organic acids, and genetic reports.
- Record head circumference, developmental milestones, infection/fasting events, and whether movement regression occurred.
- Ask whether GCDH gene testing or enzyme activity testing is needed for confirmation.
- Prepare a written emergency plan for fever, vomiting, surgery, or inability to eat.
- Arrange long-term follow-up for neurodevelopment, movement, nutrition, and kidney function.
Tests to Ask About
- Blood acylcarnitine profile, especially C5DC.
- Urine organic acids or quantitative measurement of glutaric acid and 3-hydroxyglutaric acid.
- GCDH gene testing; enzyme activity testing if needed.
- Brain MRI and neurodevelopmental assessment.
- Nutritional status, amino acids, carnitine, and kidney function monitoring.
Questions for the Doctor
- Are the results sufficient to confirm GA-1? What confirmation tests are still needed?
- Who will be responsible for daily diet and nutritional follow-up? What situations require immediate medical attention rather than home observation?
- During fever, vomiting, post-vaccine discomfort, or surgical fasting, how should the emergency protocol be carried out?
- Is there already brain or movement system involvement? Does rehabilitation or neurology follow-up need to be arranged?
- What genetic counseling is needed for siblings and future family planning?
Basic Information
Medical Notes
More complete medical explanations are kept here for discussion with clinicians.
Symptoms
GA-1 can be detected during newborn screening, or may present with an enlarged head, feeding problems, abnormal muscle tone, developmental delay, or movement disorders. In infants not managed in time, acute encephalopathy-like episodes can occur after infection, fasting, or other stressors, followed by dystonia, choreiform movements, developmental regression, and other complex movement problems.
Diagnosis
Diagnosis usually combines newborn screening, blood acylcarnitine, urine organic acids or quantitative metabolites, brain MRI, and GCDH gene testing. If molecular results are unclear, specialists may consider enzyme activity testing. Doctors will also differentiate from other organic acidemias, encephalitis, mitochondrial disease, and other movement disorders.
Treatment
Management requires a metabolic genetics team, including individualized nutrition plans, carnitine and related metabolic management, emergency protocols for infection or fasting, and developmental/movement follow-up. Specific diet, supplements, and emergency management should follow the specialist's written plan.
Long-term Care
Long-term care focuses on avoiding catabolic states, monitoring growth and nutrition, developmental and movement function, and kidney function, as well as ensuring that family members, schools, and emergency doctors all have clear emergency instructions. For those with existing movement disorders, long-term cooperation between rehabilitation, neurology, and nutrition teams is needed.
Fertility and Family
GA-1 is autosomal recessive. Once GCDH variants are identified, parents, siblings, and relatives with family planning needs can learn about carrier testing, prenatal diagnosis, or preimplantation genetic testing options through genetic counseling.
When to Seek Urgent Care
Fever or infection, repeated vomiting, inability to eat, drowsiness, sudden change in muscle tone, seizures, developmental regression, or abnormal movements — seek medical care promptly and inform providers of GA-1 or suspected organic acid metabolism disorder risk. Avoid prolonged fasting.
Prognosis
Early screening and standard management can significantly reduce the risk of acute brain injury; those with existing neurological involvement need long-term rehabilitation and follow-up.