In vivo studies on the metabolic derangement in a patient with D-glyceric acidaemia and hyperglycinaemia.

In a mentally retarded boy, who excreted elevated amounts of glycine, D-glyceric acid and acylglycines and whose cells exhibited diminished D-glycerate dehydrogenase and glycine cleavage activity, investigations have been undertaken aiming at characterizing the relationship between the different accumulations. This was done in vivo by trying in a specific manner to alter in turn the degree of accumulation of each of the three classes of compounds and then monitoring changes in the others. The results suggest, that the D-glyceric acid accumulation is directly caused by the genetic defect, since the D-glyceric acid excretion was not altered by changes in degree of accumulation of either glycine or acylglycines. Similarly alterations in acylglycine excretion caused alterations in glycine but not in D-glyceric acid excretion. Based on these findings a model for the pathogenesis behind the accumulations of acylglycines and glycine is proposed.