Fructose bisphosphatase deficiency

Fructose bisphosphatase deficiency is a single gene metabolic disorder in which the body has too little of the enzyme fructose bisphosphatase, so gluconeogenesis, the making of glucose from other molecules, cannot proceed correctly. Glycolysis, the breakdown of glucose, still works because it does not use this enzyme. Without effective gluconeogenesis, low blood sugar develops after roughly 12 hours of fasting, and fructose and glycerol cannot be used by the liver to maintain blood glucose. Acids can build up and lower the pH of the blood. Diagnosis rests on measuring the enzyme in cultured lymphocytes and confirming a mutation of the FBP1 gene. Treatment centers on avoiding long fasts and fructose containing foods and eating high carbohydrate food. The first known patient description appeared in The Lancet in 1970.