Glutaric Acidemia Type I

What is glutaric acidemia type I?

Glutaric acidemia type I is a rare inherited disorder in which the body is unable to process certain proteins properly because there are inadequate levels an enzyme in the body. Ultimately, this causes damage to the brain, particularly, the basal ganglia, which controls movement.

The overall impact of glutaric acidemia type I is dependent on the amount of brain damage that occurs, which can be severe, especially if an episode occurs before the age of six.

What causes glutaric acidemia type I?

Because there is an inadequate enzyme level in the body, individuals with glutaric acidemia type I cannot break down the amino acids lysine, hydroxylysine, and tryptophan, which are the building blocks of proteins. Thus, excessive levels of these amino acids accumulate and cause the complications of the condition.

Mutations in the GCDH gene cause the inadequate enzyme level in the body, and this mutation is inherited in an autosomal recessive pattern.

What are the symptoms of glutaric acidemia type I?

The severity of symptoms of glutaric acidemia vary widely and so does the age of onset of the condition. The characteristic symptoms of glutaric acidemia include the following:

• Unusually large heads (macrocephaly)
• Difficulty moving, which may manifest as muscle spasms, jerking, rigidity, or decreased muscle tone
• Bleeding in the brain or eyes (that can be mistaken for child abuse)
• Weak muscle tone (hypotonia)
• Developmental delay
• Frequent vomiting

How is glutaric acidemia type I diagnosed?

Glutaric acidemia type I can be diagnosed prenatally using newborn screening. After birth, an observation of the characteristic features of the disease may allow medical professionals to suspect a diagnosis, which can then be confirmed using molecular genetic testing of the GCDH gene.

What are the available treatments for glutaric acidemia type I?

If treatment is started in a newborn before symptoms begin, 80-90% of people with glutaric acidemia type 1 will not develop any symptoms. On the other hand, if not promptly and properly treated, glutaric acidemia type 1 will usually cause serious, irreversible neurologic damage. Strict dietary control (a low-lysine diet and carnitine supplementation) can help limit the progression of neurological damage. Stress caused by infection and fever may lead to signs and symptoms worsening in an acute episode of glutaric acidemia, so lifestyle changes to reduce stress in a patient’s life can also be extremely beneficial.

During fevers or acute episodes of the condition, emergency treatment is needed by medical professionals.

Where can I find more information on glutaric acidemia type I?

• U.S. National Library of Medicine
• NIH