title: X-linked creatine transporter defect: a report on two unrelated boys with a severe clinical phenotype.
abstract: 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.
authors.affiliation: Department of Neurology, Children's Hospital Boston, Harvard Medical School, Massachusetts 02115, USA.
authors.forename: I A
authors.initials: IA
authors.lastname: Anselm
authors.forename: I M
authors.initials: IM
authors.lastname: Anselm
authors.forename: F S
authors.initials: FS
authors.lastname: Alkuraya
authors.forename: G S
authors.initials: GS
authors.lastname: Salomons
authors.forename: C
authors.initials: C
authors.lastname: Jakobs
authors.forename: A B
authors.initials: AB
authors.lastname: Fulton
authors.forename: M
authors.initials: M
authors.lastname: Mazumdar
authors.forename: M
authors.initials: M
authors.lastname: Rivkin
authors.forename: R
authors.initials: R
authors.lastname: Frye
authors.forename: T Young
authors.initials: TY
authors.lastname: Poussaint
authors.forename: D
authors.initials: D
authors.lastname: Marsden
mesh_terms: D002675:Child, Preschool; D041321:Chromosomes, Human, X; D005123:Eye / Q000473:pathology; D017353:Gene Deletion; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000175:diagnosis / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D026901:Membrane Transport Proteins / Q000172:deficiency* / Q000235:genetics*; D008661:Metabolism, Inborn Errors / Q000175:diagnosis / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics; D010100:Oxygen / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D050480:Plasma Membrane Neurotransmitter Transport Proteins / Q000235:genetics
chemical_list: D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D050480:Plasma Membrane Neurotransmitter Transport Proteins; C094770:SLC6A8 protein, human; C080679:creatine transporter; D010100:Oxygen