ABSTRACT
Transient nonketotic hyperglycinemia represents a clinical presentation initially indistinguishable from the classic neonatal nonketotic hyperglycinemia. In patients with nonketotic hyperglycinemia in whom the individual components have been studied, the majority has had defects in the P-protein. Patients surviving the acute neonatal crisis develop a pattern of cerebral palsy with spasticity and hypertonia, though they may be hypotonic throughout infancy. Nonketotic hyperglycinemia is heterogeneous and, while the majority of patients display the classic phenotype, a small number has been reported in whom a variety of milder or attenuated forms have been observed. Patients with variant nonketotic hyperglycinemia can have severe or mild disease. Analysis of the protein component of the complex revealed that 87 percent had abnormalities in the P-protein, and this included all of the classic patients. The patient may be completely unaware of surroundings and have few spontaneous movements.
