Abstract
An Afghanese boy is described who presented with severe metabolic acidosis, failure to thrive and recurrent infections in the neonatal period. Symptomatic treatment with bicarbonate, combined with a low protein diet, resulted in clinical improvement. Gas chromatographic analysis of organic acids (trimethylsilyl derivatives) in the patient's urine revealed high concentrations of glyceric acid (10 to 100 mM), confirmed by mass spectrometry. Amino acid excretion was normal, especially no excess of glycine was present. The optical configuration of glyceric acid was determined as follows: isolation of the acid by paper chromatography, esterification with L-menthol and acetylation of the OH-groups. Subsequent capillary gas chromatography, stationary phase SP-1000, yielded good separation of the enantiomers. Only D-glyceric acid was found in the urine.
Glyceric acid may be derived from carbohydrate or amino acids. To elucidate its origin we loaded the patient with fructose and L-serine. Fructose loading caused no increase of glycerate excretion. On the contrary, the loading test with 200 mg/kg L-serine resulted in a significant increase of glyceric acid excretion. 25% of the ingested serine was retrieved as glyceric acid. L-serine loading in a control led to the excretion of only a trace of glyceric acid. It is suggested that the enzyme defect is located somewhere in the serine degradation pathway.
At 1½ year the patient was moderately retarded and glyceric aciduria was persistent (˜12 mmoles/day).
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Duran, M., Kamerling, J., Wadman, S. et al. 145: D-glyceric aciduria, an inborn error of serine metabolism?. Pediatr Res 10, 894 (1976). https://doi.org/10.1203/00006450-197610000-00136
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DOI: https://doi.org/10.1203/00006450-197610000-00136