A new type of idiopathic hyperglycinemia with hypo-oxaluria.

A 5½-year-old male is described, with severe mental retardation, failure to thrive, inability to make adequate muscular movements, seizures, and spasticity. Laboratory studies revealed hyperglycinuria and hyperglycinemia, but a much reduced excretion of oxalic acid in the urine. It seems likely that this represents an inborn enzymatic defect, probably of glycine oxidase.