ABSTRACT
The enzyme fructose-1,6-diphosphatase (FDP) provides an essential step in the pathway of gluconeogenesis. The enzyme catalyzes the irreversible conversion of fructose-1,6-diphosphate to fructose-6-phosphate. Another enzyme, phosphofructokinase, and adenosine triphosphate are required to take this reaction in the reverse direction. FDP deficiency is a cause of life-threatening metabolic acidosis in the neonatal period. The first symptom in the neonatal presentation is usually hyperventilation. There may be irritability, but progression is usually rapid to somnolence, coma, apnea, and cardiac arrest. Deficient activity of FDP interferes with gluconeogenesis, making the patient dependent on exogenous sources of glucose. Treatment of the acute episode of hypoglycemia and lactic acidosis is the prompt administration of generous amounts of fluid, sodium bicarbonate, and glucose. The episode usually responds readily. Dietary fructose and sucrose are avoided. In most patients, they do not have to be absolutely eliminated.
