Congenital lactic acidosis associated with pyruvate carboxylase deficiency.

Two cases of congenital lactic acidosis associated with pyruvate carboxylase deficiency are described. One 2-mo-old infant had a fulminant clinical course with extremely severe intractable acidosis and died after 48 h in hospital. The second infant, aged 2 1/2 mo, had a milder clinical course, characterized by moderate acidosis and frequent convulsive episodes. He died at the age of 3 mo due to respiratory arrest following prolonged status epilepticus. Pyruvate carboxylase activity in liver biopsy specimens obtained from the two patients was 1 and 50% of normal, respectively. Both patients failed to respond to treatment, including massive doses of thiamine and high serum levels of lactate and pyruvate were found throughout their illnesses. Cerebral autopsy performed in both cases was unremarkable. Absence of neuropathological findings ruled out the possibility of Leigh's disease.