Table 6.

Treatment of Manifestations in Individuals with GAMT Deficiency

Manifestation/ConcernTreatmentConsiderations/Other
Low cerebral creatine levels
  • Supplementation w/creatine monohydrate
  • Oral doses of 400-800 mg/kg bw/day in 3-6 divided doses
For symptomatic persons w/GAMT deficiency: 1
  • Only 1 person achieved normal development or cognitive functions on treatment; all showed some improvement.
  • Seizure freedom achieved in ~50%
  • Mvmt disorder resolved in 50%
For asymptomatic persons w/GAMT deficiency:
  • Normal neurodevelopmental outcome reported in 3 persons w/GAMT deficiency who were diagnosed & treated in neonatal period based on positive family history of disorder in older sib 2
Accumulation of neurotoxic levels of GAA
  • Supplementation w/ornithine
  • Oral doses of 400-800 mg/kg bw/day in 3-6 divided doses
  • Dietary restriction of arginine to 15-25 mg/kg/day that corresponds to 0.4-0.7 g/kg/day protein intake 3
  • To prevent protein malnutrition, essential amino acid medical formula should be supplemented (0.5-0.8 g/kg/day). 4

bw = body weight; GAA = guanidinoacetate

1.
2.
3.

Because of the challenges involved in understanding arginine restriction, reading dietary labels, and calculating arginine intake (particularly since arginine content is not always indicated), many centers use protein restriction instead.

4.

Available databases (e.g., the US Department of Agriculture National Nutrient Database) can be used to determine exact arginine content of foods to allow precise calculation of daily arginine intake in individuals with GAMT deficiency.

From: Creatine Deficiency Disorders

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