Electro-clinical features and long-term outcomes in guanidinoacetate methyltransferase (GAMT) deficiency.

Objective: To evaluate clinical characteristics and long-term outcomes in patients with guanidinoacetate methyltransferase (GAMT) deficiency with a special emphasis on seizures and electroencephalography (EEG) findings.

Methods: We retrospectively analyzed the clinical and molecular characteristics, seizure types, EEG findings, neuroimaging features, clinical severity scores, and treatment outcomes in six patients diagnosed with GAMT deficiency.

Results: Median age at presentation and diagnosis were 11.