title: Phenotypic variability in a portuguese family with x-linked creatine transport deficiency.
abstract: Cerebral creatine transporter deficiency, attributable to mutations in the SLC6A8 gene, causes X-linked mental retardation, language delay, epilepsy, and autistic features. In contrast with creatine synthesis defects, the vast majority of patients with SLC6A8 deficiency do not respond to treatment. We describe a Portuguese family with a mutation (c.456C>T; p.Gln486X) in the SL6CA8 gene: two adult monozygotic twin brothers, with psychomotor delay and severe speech impairment. The family also includes their maternal half-sister with psychomotor retardation, predominantly in language, and their mentally retarded mother. This family illustrates the remarkable phenotypic variability in this condition. Investigation of creatine metabolism is mandatory in patients with developmental delay of unknown etiology, to detect this condition.
authors.affiliation: Unidade de Doenças Metabólicas, Centro de Desenvolvimento Luís Borges, Hospital Pediátrico de Coimbra, Coimbra, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Garcia
authors.forename: Fidjy
authors.initials: F
authors.lastname: Rodrigues
authors.forename: Carla
authors.initials: C
authors.lastname: Valongo
authors.forename: Gajja S
authors.initials: GS
authors.lastname: Salomons
authors.forename: Luísa
authors.initials: L
authors.lastname: Diogo
mesh_terms: D000293:Adolescent; D020739:Brain Diseases, Metabolic, Inborn; D003401:Creatine / Q000172:deficiency / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D026901:Membrane Transport Proteins / Q000172:deficiency; D038901:X-Linked Intellectual Disability; D010641:Phenotype; D050480:Plasma Membrane Neurotransmitter Transport Proteins / Q000172:deficiency; D018433:Twin Studies as Topic; D014430:Twins, Monozygotic
chemical_list: D026901:Membrane Transport Proteins; D050480:Plasma Membrane Neurotransmitter Transport Proteins; C080679:creatine transporter; D003401:Creatine