Nonketotic hyperglycinemia in two siblings with neonatal seizures

Seizures are a common problem in neonates. Differential diagnoses include infection, trauma, hypoxia and congenital metabolic disorders. Among these, congenital metabolic disorder is less familiar to general pediatricians. We report two patients with nonketotic hyperglycinemia (NKH), a rare and lethal congenital metabolic disease. Transient hyperammonemia and transient hypouricemia, uncommon features found in NKH, were detected in one patient. High doses of sodium benzoate and dextromethorphan failed to modify the clinical course. Neuropathology denoted characteristic diffuse vacuolization and changes in reactive and gliotic astrocytes. The clinical course, biochemical findings, diagnostic approaches and diagnostic tests are discussed in detail. Recent modalities of treatment are reviewed. Because of its rarity and rapidly progressive course, it maybe underdiagnosed resulting in death before being recognized. Awareness of the possibility of congenital metabolic disorder in early neonatal catastrophe will increase the diagnostic rate.