Sravan Jaggumantri1, Mary Dunbar2, Vanessa Edgar3, Cristina Mignone4, Theresa Newlove5, Rajavel Elango6, Jean Paul Collet6, Michael Sargent4, Sylvia Stockler-Ipsiroglu7, Clara D M van Karnebeek8. 1. Division of Biochemical Diseases (TIDE-BC), Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada; Child and Family Research Institute, University of British Columbia, Vancouver, Canada. 2. Division of Pediatric Neurology, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada. 3. Division of Biochemical Diseases (TIDE-BC), Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada. 4. Department of Radiology, BC Children's Hospital, University of British Columbia, Vancouver, Canada. 5. Department of Psychology, BC Children's Hospital, University of British Columbia, Vancouver, Canada. 6. Child and Family Research Institute, University of British Columbia, Vancouver, Canada; Department of Pediatrics, University of British Columbia, Vancouver, Canada. 7. Division of Biochemical Diseases (TIDE-BC), Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada; Department of Pediatrics, University of British Columbia, Vancouver, Canada. 8. Division of Biochemical Diseases (TIDE-BC), Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada; Child and Family Research Institute, University of British Columbia, Vancouver, Canada; Department of Pediatrics, University of British Columbia, Vancouver, Canada; Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada. Electronic address: cvankarnebeek@cw.bc.ca.
Abstract
BACKGROUND: Creatine transporter (SLC6A8) deficiency is an X-linked inborn error of metabolism characterized by cerebral creatine deficiency, behavioral problems, seizures, hypotonia, and intellectual developmental disability. A third of patients are amenable to treatment with high-dose oral creatine, glycine, and L-arginine supplementation. METHODS: Given the limited treatment response, we initiated an open-label observational study to evaluate the effect of adjunct S-adenosyl methionine to further enhance intracerebral creatine synthesis. RESULTS: Significant and reproducible issues with sleep and behavior were noted in both male patients on a dose of 50/mg/kg. One of the two patients stopped S-adenosyl methionine and did not come for any follow-up. A safe and tolerable dose (17 mg/kg/day) was identified in the other patient. On magnetic resonance spectroscopy, this 8-year-old male did not show an increase in intracerebral creatine. However, significant improvement in speech/language skills, muscle mass were observed as well as in personal outcomes as defined by the family in activities related to communication and decision making. DISCUSSION: Further research is needed to assess the potential of S-adenosyl methionine as an adjunctive therapy for creatine transporter deficiency patients and to define the optimal dose. Our study also illustrates the importance of pathophysiology-based treatment, individualized outcome assessment, and patient/family participation in rare diseases research.
BACKGROUND:Creatine transporter (SLC6A8) deficiency is an X-linked inborn error of metabolism characterized by cerebral creatine deficiency, behavioral problems, seizures, hypotonia, and intellectual developmental disability. A third of patients are amenable to treatment with high-dose oral creatine, glycine, and L-arginine supplementation. METHODS: Given the limited treatment response, we initiated an open-label observational study to evaluate the effect of adjunct S-adenosyl methionine to further enhance intracerebral creatine synthesis. RESULTS: Significant and reproducible issues with sleep and behavior were noted in both male patients on a dose of 50/mg/kg. One of the two patients stopped S-adenosyl methionine and did not come for any follow-up. A safe and tolerable dose (17 mg/kg/day) was identified in the other patient. On magnetic resonance spectroscopy, this 8-year-old male did not show an increase in intracerebral creatine. However, significant improvement in speech/language skills, muscle mass were observed as well as in personal outcomes as defined by the family in activities related to communication and decision making. DISCUSSION: Further research is needed to assess the potential of S-adenosyl methionine as an adjunctive therapy for creatine transporter deficiencypatients and to define the optimal dose. Our study also illustrates the importance of pathophysiology-based treatment, individualized outcome assessment, and patient/family participation in rare diseases research.
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