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Pyruvate carboxylase (PC) deficiency (OMIM 266150) is an autosomal recessive disorder that usually presents with lactic acidaemia and severe neurological dysfunction, leading to death in infancy. Because the enzyme is involved in gluconeogenesis and anaplerosis of the Krebs cycle, therapeutic strategies have included avoiding fasting and attempts to correct the defect of anaplerosis. Triheptanoin is a triglyceride of C7 fatty acids. The oxidation of odd chain fatty acids leads to the production not only of acetyl-CoA but also of propionyl-CoA, which is an anaplerotic substrate for the Krebs cycle. One infant with PC deficiency has previously been treated with triheptanoin as well as citrate and 2-chloropropionate. We report two further patients with PC deficiency, who were treated with triheptanoin, continuously from 11 and 21 days of age. They were also given citrate, aspartate and dichloroacetate. Triheptanoin did not lead to any clinical or biochemical improvement. The plasma and CSF lactate concentrations remained high with episodes of severe ketoacidosis and lactic acidosis. Both patients had severe hearing loss, roving eye movements, seizures and very limited neurodevelopmental progress; they died at the ages of 7 and 8 months. Conclusion: Though triheptanoin did not alter the clinical course in our patients, it was well tolerated. It remains possible that less severely affected patients might benefit from this form of therapy. [ABSTRACT FROM AUTHOR]

Two children are described who suffered from episodes of metabolic acidosis and progressive mental and motor deterioration. The patients showed periodic elevation of blood lactate, pyruvate and alanine, which was accompanied by vomiting, hypotonia or convulsions. The concentrations of lactate and pyruvate in cerebrospinal fluid were found to be increased. Liver biopsies revealed a decrease in pyruvate carboxylase activity and normal pyruvate decarboxylase activity. No inhibitor of TPP-ATP phosphoryl transferase was detected in urine from the patients. These findings suggest that congenital lactic acidosis due to pyruvate carboxylase deficiency is probably a different disease entity from Leigh's encephalomyelopathy. A possible mechanism of brain damage caused by a defect in pyruvate carboxylase is postulated. [ABSTRACT FROM AUTHOR]

A 16-month-old female infant with severe mental and motor retardation, clinically diagnosed as Leigh's encephalomyelopathy, forms the basis of this study. This infant was found to have lactic acidosis, low cerebrospinal fluid glucose, hyperalaninemia, and increased levels of urine lactate, pyruvate and alanine. These laboratory studies suggested an inborn error in gluconeogenesis. Further investigation revealed a low level of hepatic pyruvate carboxylase activity. The patient's elder sister who also had mental and motor deterioration was then also found to have an elevated blood lactate. These two siblings clinically and biochemically showed improvement with treatment consisting of thiamine and lipoic acid. [ABSTRACT FROM AUTHOR]