OTC deficiency is an X-linked disorder in which the synthesis of urea is impaired. OTC catalyzes the synthesis of citrulline from carbamyl phosphate and ornithine. Complete or partial deficiencies of this enzyme may lead to Reye syndrome like picture such as encephalopathy, hepatic dysfunction, hyperammonemia, etc. We recently had a case that was presented as recurrent Reye syndrome, and was effectively treated with hemodialysis, arginine, sodium benzoate, etc. This report describes an experience in treating this condition with review of available literature.
Arginine ; Carbamyl Phosphate ; Citrulline ; Hepatic Encephalopathy ; Hyperammonemia ; Ornithine Carbamoyltransferase Deficiency Disease ; Ornithine Carbamoyltransferase* ; Ornithine* ; Renal Dialysis ; Reye Syndrome ; Sodium Benzoate ; Urea

The amino acids formed by degradation of proteins ingested produce ammonia. The ammonia which is broken down and excreted as urea through a process known as the Klebs-Hensleit cycle or the urea cycle. 1) The urea cycle consists of five enzymes necessary for the synthesis of carbamyl phosphate, citrulline, argininosuccinate, arginine, and urea: carbamyl phosphate synthetase (CPS), ornithine transcarbamylase (OTC), argininosuccinate synthetase (AS), argininosuccinate lyase (AL), and arginase (ARG). 2) Congenital deficiencies of the enzymes involved in the urea cycle are diseases that are almost fatal without treatment, showing symptoms like vomiting, lethargy, dyspnea, and coma due to hyperammonemia coming from the accumulation of ammonia and metabolic precursors resulting from the deficiency of one of these enzymes. 3) Among these, the disease manifested by the congenital deficiency of argininosuccinate synthetase (AS) which is associated with the formation of argininosuccinate in citrulline is called argininosuccinate synthetase deficiency or citrullinemia. There have been two reports on this so far in Korea; one in July 1987 by Kim et al. 4) and the other by Park et al. 5) in 1995. We are to report a case of successful treatment of a child with citrullinemia who was transferred to our hospital due to dyspnea, lethargy, feeding difficulties, convulsions and cyanosis together with some document studies related to this case.
Amino Acids ; Ammonia ; Arginase ; Arginine ; Argininosuccinate Lyase ; Argininosuccinate Synthase ; Carbamyl Phosphate ; Child* ; Citrulline ; Citrullinemia* ; Coma ; Cyanosis ; Dyspnea ; Humans ; Hyperammonemia ; Korea ; Lethargy ; Ligases ; Ornithine Carbamoyltransferase ; Seizures ; Urea ; Urea Cycle Disorders, Inborn ; Vomiting

Ornithine transcarbamylase (OTC) deficiency is the most common inborn error of urea cycle metabolism; it is inherited in an X-linked manner. The OTC catalyzes the third step of the urea cycle, the conversion of ornithine and carbamyl phosphate to citrulline. Deficiency of OTC leads to the accumulation of ammonia, causing neurological deficits. In most affected hemizygote males, OTC deficiency manifests as hyperammonemic coma that often leads to death in the newborn period, and those who recover from the coma may be neurologically impaired due to the sequelae of the hyperammonemic encephalopathy. In some, late-onset manifestations develop. We report a male neonate with early onset OT deficiency that had apnea and was comatous. On mutation analysis using DNA sequencing after polymerase chain reaction (PCR) amplification of the 10 exons, deletions of 10 bases in codon 285, causing a frame shift was detected in exon 8. The mother and a sister were diagnosed as female carriers. Therefore, genetic counseling and the risk assessment could be provided to the family.
Ammonia ; Apnea ; Carbamyl Phosphate ; Citrulline ; Codon ; Coma ; Diagnosis* ; Exons ; Female ; Genetic Counseling ; Hemizygote ; Humans ; Infant, Newborn ; Male ; Metabolism ; Mothers ; Ornithine Carbamoyltransferase Deficiency Disease* ; Ornithine Carbamoyltransferase* ; Ornithine* ; Polymerase Chain Reaction ; Risk Assessment ; Sequence Analysis, DNA ; Siblings ; Urea