Short Report

Journal of Inherited Metabolic Disease

, Volume 29, Issue 1, pp 214-219

First online:

X-linked creatine transporter defect: A report on two unrelated boys with a severe clinical phenotype

  • I. M. AnselmAffiliated withDepartment of Neurology, Children’s Hospital Boston, Harvard Medical School
  • , F. S. AlkurayaAffiliated withDivision of Genetics and Metabolism, Children’s Hospital Boston, Harvard Medical School
  • , G. S. SalomonsAffiliated withDepartment of Clinical Chemistry, Metabolic Unit, VU University Medical Center
  • , C. JakobsAffiliated withDepartment of Clinical Chemistry, Metabolic Unit, VU University Medical Center
  • , A. B. FultonAffiliated withDepartment of Ophthalmology, Children’s Hospital Boston, Harvard Medical School
  • , M. MazumdarAffiliated withDepartment of Neurology, Children’s Hospital Boston, Harvard Medical School
  • , M. RivkinAffiliated withDepartment of Neurology, Children’s Hospital Boston, Harvard Medical School
  • , R. FryeAffiliated withDepartment of Neurology, Children’s Hospital Boston, Harvard Medical School
  • , T. Young PoussaintAffiliated withDepartment of Radiology, Children’s Hospital Boston, Harvard Medical School
    • , D. MarsdenAffiliated withDivision of Genetics and Metabolism, Children’s Hospital Boston, Harvard Medical School Email author 

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Summary

We report two unrelated boys with the X-linked creatine transporter defect (CRTR) and clinical features more severe than those previously described with this disorder. These two boys presented at ages 12 and 30 months with severe mental retardation, absent speech development, hypotonia, myopathy and extra-pyramidal movement disorder. One boy has seizures and some dysmorphic features; he also has evidence of an oxidative phosphorylation defect. They both had classical absence of creatine peak on brain magnetic resonance spectroscopy (MRS). In one, however, this critical finding was overlooked in the initial interpretation and was discovered upon subsequent review of the MRS. Molecular studies showed large genomic deletions of a large part of the 3′ end of the complete open reading frame of the SLC6A8 gene. This report emphasizes the importance of MRS in evaluating neurological symptoms, broadens the phenotypic spectrum of CRTR and adds knowledge about the pathogenesis of creatine depletion in the brain and retina.