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Two novel mutations in SLC6A8 cause creatine transporter defect and distinctive X-linked mental retardation in two unrelated Dutch families†
Article first published online: 22 DEC 2004
Copyright © 2004 Wiley-Liss, Inc.
American Journal of Medical Genetics Part A
Volume 132A, Issue 3, pages 288–295, 30 January 2005
How to Cite
Mancini, G.M.S., Catsman-Berrevoets, C.E., de Coo, I.F.M., Aarsen, F.K., Kamphoven, J.H.J., Huijmans, J.G., Duran, M., van der Knaap, M.S., Jakobs, C. and Salomons, G.S. (2005), Two novel mutations in SLC6A8 cause creatine transporter defect and distinctive X-linked mental retardation in two unrelated Dutch families. Am. J. Med. Genet., 132A: 288–295. doi: 10.1002/ajmg.a.30473
- Issue published online: 22 DEC 2004
- Article first published online: 22 DEC 2004
- Manuscript Accepted: 30 SEP 2004
- Manuscript Received: 11 MAR 2004
- semantic-pragmatic language disorder;
- oral dyspraxia;
Four Dutch male patients, two brothers from unrelated families were referred for investigation of psychomotor and severe language/speech delay. All four patients showed growth deficiency over the years. Facial features and poor body habitus were quite similar in the patients and in their mothers. Brain MRI showed nonspecific periventricular white matter lesions. In all the patients neuropsychological tests revealed moderate mental retardation, attention deficit and hyperactivity with impulsivity, a semantic-pragmatic language disorder, and oral dyspraxia. This specific cognitive profile is different from other children with mental retardation syndromes and seems to be unique. Excretion of creatine to creatinine ratio in urine of the four boys was increased compared to controls and their creatine uptake in fibroblasts was deficient. In the two brothers from the first pedigree, DNA sequence analysis revealed a novel mutation in the splice donor site in intron 10 (IVS10 + 5G>C, c.1495 + 5G>C) of the SLC6A8 gene leading to skipping of exon 10. In the other sib pair a novel missense mutation (c. 1361C>T; p.Pro544Leu) was found. These are the first families reported, in which the clinical suspicion of a creatine transporter disorder was raised on clinical grounds, before a brain 1H-MRS suggested the diagnosis. Screening of apparently X-linked mental retarded patients with this somatic and behavioral phenotype by the biochemical assay of creatine to creatinine ratio in the urine or DNA sequence analysis of SLC6A8 is worthwhile even when 1H-MRS is not available. © 2004 Wiley-Liss, Inc.