A novel AMT gene mutation in a newborn with nonketotic hyperglycinemia and early myoclonic encephalopathy

• Early myoclonic encephalopathy (EME) presents in neonatal period.
• Nonketotic hyperglycinemia (NKH) is the most common metabolic cause of EME.
• The neurological damage in NKH is caused by NMDA receptor overstimulation.

Early myoclonic encephalopathy (EME) presents in neonatal period with erratic or fragmentary myoclonus and a burst-suppression electroencephalography (EEG) pattern. Nonketotic hyperglycinemia (NKH) is the most common metabolic cause of EME and genetic testing confirms the diagnosis of NKH in around 75% of the patients with a clinical diagnosis of NKH. Three genes are known to cause NKH.Here we describe a case of EME caused by NKH in which a new mutation in aminomethyltransferase (AMT) gene has been detected.