Fructose-1,6-diphosphatase deficiency: Another enzyme defect which can present itself with the clinical features of “tyrosinosis”

An infant with a picture of hereditary liver disease corresponding in many respects with so-called “tyrosinosis” is described. The primary defect appeared to be fructose-l,6-diphosphatase deficiency, which was not recognized during the patient's life. Many abnormalities of amino acid metabolism and transport occurred when the patient was on a diet containing saccharose. At that time tyrosyluria was excessive and serum tyrosine strongly elevated. Serum methionine was moderately increased, but a striking cystathioninuria was present and once even homocystine was traced in the urine. In the serum alanine was excessive, but also phenylalanine, lysine, proline, valine, threonine, leucine, serine and other amino acids were increased. There was a generalized amino aciduria and a massive lactic aciduria. Once even phenyllactic acid was found in the urine. When the diagnosis “tyrosinosis” is proposed, fructose-1,6-diphosphatase deficiency as a primary cause should also be kept in mind