Hypotonia is a serious physical finding in a newborn infant. Nonketotic hyperglycinemia (NKH) is a rare cause of neonatal hypotonia. It is a defect of the glycine metabolism and has poor prognosis. We report a case of a newborn infant with NKH, presented with mild hypotonia and high creatine kinase values. NKH should be considered in a hypotonic newborn, especially if associated with acute deterioration, lethargy and seizures.

Hypotonia is a serious physical finding in a newborn infant. Nonketotic hyperglycinemia (NKH) is a rare cause of neonatal hypotonia. It is a defect of the glycine metabolism and has poor prognosis. We report a case of a newborn infant with NKH, presented with mild hypotonia and high creatine kinase values. NKH should be considered in a hypotonic newborn, especially if associated with acute deterioration, lethargy and seizures.