Deficiency of glycerol kinase (EC 2.7.1.30)

We describe the case of a 10-year-old boy who had been admitted on several occasions with a diagnosis of gastroenteritis. He had been severely ill, and on one occasion lost consciousness. He had a metabolic acidosis on these occasions. Examination of the urine by gas chromatography-mass spectrometry showed a large peak, identified as glycerol. The concentration of glycerol in the urine was 40-280 mmol/L and the concentration in plasma about 2 mmol/L. He was subjected to a fast of 21 h, at the end of which he expressed feelings of discomfort and nausea, began vomiting, and became somnolent. During this period the blood glucose concentration was only slightly decreased, the plasma glycerol concentration increased to 4.9 mmol/L, and the plasma lactate concentration increased to 3.8 mmol/L. During work on a bicycle ergometer for 35 min (40 W) he complained of muscle pain and became nauseated, but there was no significant increase in the concentration of plasma glycerol. The activity of glycerol kinase (EC 2.7.1.30) in leukocytes and cultured fibroblasts was less than 1% of the value for healthy subjects.