A novel variation of gamt in cerebral creatine deficiency syndrome, first complete homozygous deletion of GAMT

Abstract

Cerebral Creatine Deficiency Syndromes (CCDS) are congenital metabolic disorders in the creatine metabolism pathway. In this study, we evaluated the clinical, phenotypic, radiological and genetic features of patients with CCDS. We tried to identify early diagnosis clues in patients. Especially, we reviewed the causes of delay in patients with late diagnosis. In line with these findings, the diagnosis is confirmed by enzyme tests and next generation sequencing based whole genome sequencing. In this study, 6 patients whose diagnosis was genetically confirmed were presented (5 GAMT mutations (someone is complete homozygous deletion in GAMT gene), 1 SLC6A8 mutation). 5 of these patients were from the same family, and 4 patients were patients with a late diagnosis. Two of the 4 patients who were diagnosed late were moderate and two had severe phenotype. The neurological findings consisted of patients with different clinical findings such as speech disorder, cognitive retardation, autism and epilepsy. Patients received appropriate treatment for the type of cerebral creatine deficiency. While response to treatment was good in early diagnosed cases, a partial clinical improvement was detected in cases diagnosed late. The patient, who was started treatment before neurological symptoms appeared, was neurodevelopmentally normal. It was observed that there was a strong relationship between age at diagnosis and phenotype and prognosis. We compared the clinical findings, phenotype and genotype characteristics of patients with CCDS. We reviewed the causes of delay in patients with late diagnosis. Thus, we wanted to raise awareness about early diagnosis and treatment of CCDS, one of the rare metabolic diseases.