Ornithine Transcarbamylase Deficiency

Abstract

ORNITHINE transcarbamylase (OTC), the second enzyme in the Krebs—Henseleit urea cycle, catalyzes the formation of citrulline from ornithine and carbamyl phosphate in hepatic mitochondria. Inherited, virtually complete deficiency of OTC causes lethal neonatal hyperammonemia in affected male infants.^{1 , 2} Orotic aciduria is also observed in these patients, presumably because carbamyl phosphate accumulates behind the block, enters the cytoplasm, and serves as a substrate for pyrimidine biosynthesis.^{2 , 3} All previous attempted therapeutic measures, including oral antibiotics, enemas, lactulose, peritoneal dialysis, and exchange transfusion, have been unsuccessful in altering the uniformally fatal outcome in these newborn male infants.^{1 , 2} We report here an unsuccessful attempt . . .