Organic acidurias : proceedings of the ninth symposium of the Society for the Study of Inborn Errors of Metabolism / edited by J. Stern and C. Toothill.

  • Society for the Study of Inborn Errors of Metabolism.
Date:
1972
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Organic acidurias : proceedings of the ninth symposium of the Society for the Study of Inborn Errors of Metabolism / edited by J. Stern and C. Toothill. Source: Wellcome Collection.

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    2 ORGANIC ACIDURIAS related to careful management. It is also clear that all patients with this syndrome do not necessarily develop ketones in the urine in every acute episode of overwhelming illness. Obviously a number of conditions come immediately to mind which present with this clinical picture. Glycine Concentrations in Blood Another way of looking at the problem is to consider conditions in which there are elevated amounts of glycine in blood and urine. Obviously the two lists would not include all of the same conditions. Fig. 2 provides a list of conditions in which there is hyperglycinaemia. The condition we originally described as ketotic hyperglycinaemia is now generally recognised to be a primary propionic acidaemia. It is also widely known that patients with methylmalonic acidaemia have elevated concen¬ trations of glycine in the blood. They do not always, but they do much of the time, and the elevations can be quite high. It is not so generally appreciated that patients with isovaleric acidaemia may not only have a clinical syndrome like that described above but may also have an elevated concentration of glycine in the blood. We have reported a patient with isovaleric acidaemia, recently published (Ando et al., 1971a), who was initially referred to as a patient with ketotic hyperglycinaemia. It is our conviction that this list will grow. Ketosis and metabolic acidosis Ketotic hyperglycinaemia, propionic acidaemia—propionyl CoA carboxylase deficiency Methylmalonic acidaemia В12 responsive В12 nonresponsive with homocystinuria Isovaleric acidaemia Nonketotic Primary hyperglycinaemia Defective conversion of carbon 1 to CO 2 and carbon 2 to 1 carbon unit Fig. 2. Classification of conditions which may present with hyperglycinaemia. Amino Acid Intolerance A listing of the components of protein which are capable individually of inducing symptoms of ketoacidosis in patients with ketotic hyperglycin¬ aemia indicates that we are dealing with a multiple amino acid toxicity. Leucine, isoleucine, valine, threonine and methionine are all toxic, while the rest are innocuous. A similar list could be assembled in methylmalonic acidaemia except that leucine is non-toxic in this condition. Furthermore, we have now completed studies which indicate that isoleucine, valine, threonine and methionine are imperfectly metabolised in methylmalonic acidaemia and serve as sources of methylmalonic acid. This is consistent