Fumaric aciduria

C-IO) Fumarase deficiency. There is a deficit in the transformation of fumarate to malate. The infant has developmental retardation, with abnormal neuromuscular function, lactic acidemia, and fumarate aciduria. The lactic acidosis may result from a backup of Krebs cycle function, all the way to lactate. Lactic acidosis may also be present in rare disorders of cytochrome oxidase activity. Diagnostically, there is a deficit in fumarase activity in assay of liver and skeletal muscle mitochondria. 

In addition two mentally retarded adults with fumaric aciduria have been described, but the abnormality was thought to be due to a renal fumaric acid resorption defect. Fumarase activity was not determined in these patients. 

Kerrigan JF, Aleck KA, Tarby TJ, Bird CR, Heidenreich RA. Fumaric aciduria Clinical and Imaging Features. Ann Neurol 2000 47 583-588... 

Argininosuccinic aciduria results from a defective argininosuccinate lyase, mediating the cleavage of argininosuccinic acid to arginine and fumaric acid (Fig. 8). 

---