Identification of novel variations in SLC6A8 and GAMT genes causing cerebral creatine deficiency syndrome

•The use of NGS is an efficient technique to diagnose cerebral creatine deficiency syndrome precisely.•A combined mass spectrometry with gene mutation analysis is helpful in CCDS diagnosis.•Genetic diagnosis determined that all seven patients were positive for SLC6A8 or GAMT variation.•A total of 12 variants were identified in this cohort, including six novel ones.