What dietary measures can prevent metabolic crises in a child with GA I?

low‑lysine, low‑tryptophan diet supplemented with a specialized medical formula reduces the precursors that generate toxic acids. Frequent meals, avoidance of fasting, and rapid‑acting carbohydrate during illness also help maintain metabolic stability.

Are there long‑term therapies that improve neurological outcomes?

In addition to diet, carnitine supplementation supports fatty‑acid transport, and riboflavin may enhance residual enzyme activity in some genotypes. Early physiotherapy, occupational therapy, and, when indicated, deep‑brain stimulation for severe dystonia can improve motor function.

Is glutaric acidemia type I detected on routine newborn screening, and what follow‑up is needed?

Many newborn panels include elevated glutarylcarnitine (C5DC) as a marker. A positive screen prompts confirmatory plasma amino‑acid and urine organic‑acid analysis, followed by enzymatic or molecular testing for GCDH mutations.

What are the warning signs of an acute encephalopathic crisis and when should I go to the emergency department?

Sudden vomiting, lethargy, seizures, or a rapid change in muscle tone (rigidity or dystonia) after a fever, infection, or prolonged fasting signal a crisis. Seek emergency care immediately; prompt IV glucose and ammonia‑lowering therapy are critical.

Glutaric acidemia type I

Glutaric acidemia type I is an inherited organic acid disorder that impairs the body's ability to break down certain proteins, leading to a toxic buildup of organic acids that can cause brain damage and movement difficulties.

Overview

Glutaric acidemia type I (also called glutaric aciduria type I) is an inherited disorder in which the body is unable to process certain proteins properly. It is classified as an organic acid disorder, which is a condition that leads to an abnormal buildup of particular acids known as organic acids. Abnormal levels of organic acids in the blood (organic acidemia), urine (organic aciduria), and tissues can be toxic and can cause serious health problems.

People with glutaric acidemia type I have inadequate levels of an enzyme that helps break down the amino acids lysine, hydroxylysine, and tryptophan, which are building blocks of protein. Excessive levels of these amino acids and their intermediate breakdown products can accumulate and cause damage to the brain, particularly the basal ganglia, which are regions that help control movement. Intellectual disability may also occur.

The severity of glutaric acidemia type I varies widely; some individuals are only mildly affected, while others have severe problems. In most cases, signs and symptoms first occur in infancy or childhood, but in a small number of affected individuals, the disorder first becomes apparent in adolescence or adulthood.

Symptoms

Signs and symptoms of glutaric acidemia type I can include:

Unusually large heads (macrocephaly)
Difficulty moving
Spasms, jerking, or rigidity
Decreased muscle tone (hypotonia)
Bleeding in the brain or eyes (which could be mistaken for the effects of child abuse)

Stress caused by infection, fever, or other demands on the body may lead to worsening of the signs and symptoms, with only partial recovery. Strict dietary control may help limit the progression of neurological damage.

Frequency

Glutaric acidemia type I occurs in approximately 1 in 100,000 individuals. It is much more common in the Amish community and in the Ojibwa population of Canada, where up to 1 in 300 newborns may be affected.

Causes

Mutations in the GCDH gene cause glutaric acidemia type I. The GCDH gene provides instructions for making the enzyme glutaryl-CoA dehydrogenase. This enzyme is involved in processing the amino acids lysine, hydroxylysine, and tryptophan.

Mutations in the GCDH gene prevent production of the enzyme or result in the production of a defective enzyme that cannot function. A shortage (deficiency) of this enzyme allows lysine, hydroxylysine, and tryptophan and their intermediate breakdown products to build up to abnormal levels, especially at times when the body is under stress.

The intermediate breakdown products resulting from incomplete processing of lysine, hydroxylysine, and tryptophan can damage the brain, particularly the basal ganglia, causing the signs and symptoms of glutaric acidemia type I.

Associated Genes

GCDH

Inheritance

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Other Names for This Condition

GA I
Glutaric acidemia I
Glutaric acidemia type 1
Glutaric aciduria I
Glutaryl-CoA dehydrogenase deficiency

Additional Information & Resources

Genetic Testing Information

Genetic Testing Registry: Glutaric aciduria, type 1

Genetic and Rare Diseases Information Center

Glutaryl-CoA dehydrogenase deficiency

Patient Support and Advocacy Resources

National Organization for Rare Disorders (NORD)