Treatment efficacy of high-dose creatine supplementation in a child with creatine transporter (SLC6A8) deficiency.

ABSTRACT

BACKGROUND: Creatine transporter deficiency is an inborn error of metabolism caused by a deficiency in the creatine transporter protein encoded by the SLC6A8 gene. Previous treatment with creatine supplementation, either alone or in combination with creatine precursors (arginine or glycine), has been attempted; the efficacy of therapy, however, remains controversial. METHODS AND RESULTS: To analyze the treatment efficacy of high-dose creatine supplementation on creatine transporter deficiency, we reported a child diagnosed with creatine transporter deficiency, who was treated with a conventional dose of creatine (400 mg/kg/d) for 1 month, then twice the dose (800 mg/kg/d) for 2 months, and finally 3 times the dose (1200 mg/kg/d) for 3 months. The patient tolerated the treatment well and showed improvements in muscle mass and strength when the creatine dose was gradually increased to 1200 mg/kg/d. However, when assessed by proton magnetic resonance spectroscopy (H-MRS), the brain creatine concentration did not increase, and there was no improvement in speech and neurodevelopmental symptoms. CONCLUSION: We conclude that high-dose creatine supplementation (1200 mg/kg/d) alone improved muscular symptoms, but did not improve cognitive symptoms and brain creatine concentration assessed using H-MRS. Therefore, new treatment strategies are required for the management of creatine transporter deficiency.