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Guanidinoacetate methyltransferase deficiency

(GWAH-nih-dih-NOH-AS-uh-tayt • METH-uhl-TRANS-fuhr-ace • di-FISH-uhn-see)

General Condition Information

Other Names

  • GAMT
  • GAMT Deficiency
  • Guanidinoacetate Methyltransferase (GAMT) Deficiency

Condition Type

Birth Prevalence

  • It is unknown how many babies are born with this rare condition each year in the United States.
  • Visit GeneReviews to learn more about how often this condition occurs.

Screening Finding

Increased guanidinoacetate (GAA) usually with decreased creatine and increased guanidinoacetate/creatine ratio

What is guanidinoacetate methyltransferase deficiency

Guanidinoacetate methyltransferase (GAMT) deficiency is an inherited (genetic) condition that prevents the body from making a substance called creatine. Creatine helps store and use energy.

GAMT is an enzyme that helps make creatine from another substance called guanidinoacetate.

GAMT deficiency means GAMT is present at low levels or does not work correctly. This makes it harder for the body to produce creatine. Without enough creatine, the organs do not get enough energy.

Left untreated, low levels of creatine and high levels of guanidinoacetate can damage the body’s organs, especially those that need a lot of energy, like the brain and muscles. This damage leads to the signs and symptoms of the condition.

Newborn Screening and Follow-Up

Condition Details

Treatment and Management

It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.

Treatments may include the following:

  • Creatine and ornithine supplements
  • Sodium benzoate, a medication that can reduce levels of an amino acid called glycine
  • Medications to treat seizures
  • Special diet low in protein
  • Speech, occupational, and behavior therapy

Children who receive early and ongoing treatment for GAMT deficiency can live longer and have better outcomes.

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