Non-ketotic hyperglycinaemia due to a deficiency of T-protein in the glycine cleavage system in liver and brain.

Non-ketotic hyperglycinaemia was diagnosed in a girl at 3 weeks of age because of the typical clinical presentation, the elevated glycine concentration in urine, plasma and especially in cerebrospinal fluid and the normal profile of organic acids in urine. An EEG showed the typical burst suppression pattern. Therapeutic approaches with either pyridoxine (50 mg d-1) alone or in combination with N5-formyltetrahydrofolate (3 X 3 mg d-1) or with strychnine (0.3 mg per kg body weight) did not result in improvement. In postmortem liver and brain of the patient the overall activity of the glycine cleavage system was deficient; examination of the activity of the individual components of the glycine cleavage system in the tissues revealed that the activity of the T-protein was undetectable, whereas that of the other components and of lipoamide dehydrogenase was normal.