Diagnosis of X-Linked creatine transporter deficiency in a patient from Northeast China

ABSTRACT

Background: Creatine transporter (CRTR) deficiency is the most common creatine deficiency syndrome, of which the final diagnosis relies on mutation in the X-linked CRTR gene. To date, more than 90 mutations in the SLC6A8 gene have been reported. This paper discusses a novel mutation detected via the thorough sequencing of all the X-chromosome-specific exons investigated in a four and a half year old boy with an intellectual disability, speech and language delay and motor disturbance. Methods: A brain magnetic resonance imaging (MRI) and a proton magnetic resonance spectroscopy (MRS) were carried out, the creatine and creatinine concentrations in the urine were checked and all exons were sequenced. Results: A detailed clinical investigation revealed a reduction in the cerebral creatine levels in the brain by the MRS, elevated creatine and creatinine concentrations in the urine and signal abnormalities in the left frontal cortex of the brain by the MRI. A novel change was identified in the heterozygosity of the exon 10: c.1395-c.1401 deletion. Conclusion: The use of a combination of powerful new technologies, such as thorough exome-nextgeneration sequencing and a brain MRS, should be considered, in order to determine any neurometabolic diseases, especially when the signal abnormalities in the brain MRI cannot be explained by any other factors. This mutation results most likely in a dysfunction of the creatine transport and synthesis, hence causing central nervous system symptoms.