Mitochondrial abnormalities of liver in two children with citrullinaemia.

Citrullinaemia is a rare inborn error of urea-cycle metabolism. Two affected children are reported in whom progressive metabolic instability suggested the possibility of hepatopathy or an ongoing hepatic mitochondrial injury. A percutaneous liver biopsy was performed in each patient. Electron-microscopic findings were similar in both cases. Approximately 20% of the mitochondria were abnormally enlarged with paracrystalline inclusions and electron-dense bodies of different sizes and shapes present in the matrix. The specificity of these findings is discussed in the context of previous reports of ultrastructural abnormalities in the hepatocytes of patients with inborn errors of the urea cycle. It is speculated that the mitochondrial abnormalities in citrullinaemia may be related to the accumulation of citrulline in the mitochondria which may eventually manifest as metabolic instability.