Neonatal hyperammonemia and citrullinemia caused by argininosuccinate lyase gene mutations / 中华围产医学杂志

ObjectiveTo analyze the characteristics of neonatal hyperammonemia and citrullinemia caused by argininosuccinate lyase (ASL) gene mutations, and to have a better understanding of this disease. MethodsA neonatal patient with the onset of hyperammonemia and citrullinemia admitted to the Department of Pediatrics of Peking University First Hospital on April 2, 2014, was retrospectively studied. Peripheral blood leukocyte DNA of the patient and his parents was collected to detectASS1,ASL andSLC25A13 gene mutations. The literature related to neonatal hyperammonemia, citrullinemia and argininosuccinic aciduria was reviewed. ResultsThe baby in this case appeared lethargic, had weaker crying and food refusal since three days after birth, and analysis of blood amino acid found a marked increase in blood ammonia (1 332μmol/L) and a significant rise in citrulline (759.12μmol/L). Sanger sequencing detection revealed compound heterozygous mutations in theASL gene (c.434 A>G, c.857A>C) and this c.857A>C mutation was the first reported case in China. This case of hyperammonemia and citrullinemia was confirmed as argininosuccinic aciduria caused by ASL gene mutations. A protein-limited diet and the treatment of arginine and L-carnitine were given. His blood ammonia decreased to normal level and there was a significant improvement in physical and intellectual progress at five months old. Unfortunately, he had an intestinal infection when he was over five months old and the blood ammonia level tested in the local hospital was 480μmol/L. Gradually there was a disturbance of consciousness, then coma, and he finally died after active rescue in the local hospital.ConclusionsHyperammonemia and citrullinemia in neonates are likely to be argininosuccinic aciduria and a gene mutation test may be helpful for diagnosis.

A case of neonatal death due to argininosuccinic aciduria / 临床儿科杂志

Objectives To report the ifrst Chinese case of early onset argininosuccinic aciduria. Methods A girl aged three days was admitted because of vomiting and lethargy from the second day of life. General laboratory examination, blood amino acids analysis, urine organic acids tests and gene studies were performed for the diagnosis. Results Severe hyperam-monemia, liver dysfunction, metabolic acidosis, hypokalemia and hypocalcemia were found. Bood citrulline was extremely elevated (1098.12μmol/L vs normal range 5 to 25μmol/L), while blood arginine was decreased. Urine orotic acid, uracil and argininosuccinic acid were signiifcantly elevated. Two known heterozygosis mutations on ASL gene, c.544C>T (p.R182X) and c.706C>T (p.R236W), conifrmed the diagnosis of argininosuccinic aciduria. Unfortunately, protein-restricted diet with L-arginine supplement showed no effect. The patient died at the 23th day of life. Conclusions Argininosuccinic aciduria is a severe inherit-ed metabolic disorder. Clinical diagnosis is dififcult. It is characterized biochemically by severe citrullinemia. Urine organic acids analysis and ASL gene analysis are important for the differential diagnosis. In this study, a case of neonate death due to early-on-set argininosuccinic aciduria was diagnosed by post-mortem investigation. ASL gene study is helpful for the genetic counseling and prenatal diagnosis of the disease.

Targeting Arginine-Dependent Cancers with Arginine-Degrading Enzymes: Opportunities and Challenges / Journal of the Korean Cancer Association, 대한암학회지

Arginine deprivation is a novel antimetabolite strategy for the treatment of arginine-dependent cancers that exploits differential expression and regulation of key urea cycle enzymes. Several studies have focused on inactivation of argininosuccinate synthetase 1 (ASS1) in a range of malignancies, including melanoma, hepatocellular carcinoma (HCC), mesothelial and urological cancers, sarcomas, and lymphomas. Epigenetic silencing has been identified as a key mechanism for loss of the tumor suppressor role of ASS1 leading to tumoral dependence on exogenous arginine. More recently, dysregulation of argininosuccinate lyase has been documented in a subset of arginine auxotrophic glioblastoma multiforme, HCC and in fumarate hydratase-mutant renal cancers. Clinical trials of several arginine depletors are ongoing, including pegylated arginine deiminase (ADI-PEG20, Polaris Group) and bioengineered forms of human arginase. ADI-PEG20 is furthest along the path of clinical development from combinatorial phase 1 to phase 3 trials and is described in more detail. The challenge will be to identify tumors sensitive to drugs such as ADI-PEG20 and integrate these agents into multimodality drug regimens using imaging and tissue/fluid-based biomarkers as predictors of response. Lastly, resistance pathways to arginine deprivation require further study to optimize arginine-targeted therapies in the oncology clinic.

The First Neonatal Case of Neonatal Argininosuccinic Aciduria in Korea

Argininosuccinic aciduria (ASAuria) is a rare autosomal recessive urea cycle disorder. Neonatal presentation of ASAuria is the most common form. It is characterized by lethargy, feeding intolerance, decreased consciousness, and coma after 24 to 72 hours of birth. We describe a rare case of ASAuria in a female neonate who presented with severe hyperammonemia, a typical characteristic of urea cycle disorders. This patient's diagnosis was confirmed by biochemical analyses, and we found that the patient had a point mutation of the argininosuccinate lyase gene, which was homozygous for a novel 556C>T substitution. We have never seen the neonatal form of ASAuria in Korea. Therefore, this is the first report of neonatal onset ASAuria in Korea.

Establishment of enzymatic kinetic assay of serum argininosuccinate lyase activity and its preliminary clinical application / 中华检验医学杂志

Objective To establish a continuous monitoring assay of serum argininosuccinate lyase (ASL) activity with automatic biochemistry analyzer, and perform methodology validation and preliminary clinical application.Methods According to the chemical reaction catalyzed by ASL and the working characteristics of automatic biochemistry analyzer, an enzyme coupled reaction system with high specificity was set up, and the methodology validation was performed.Three hundred and nine patients with various liver diseases, 269 non-liver disease patients and 40 healthy controls were enrolled in this study.Serum ASL, ALT, and AST level were determined in all subjects.Results A new kinetics assay of ASL activity was set up with automatic biochemistry analyzer.The methodological validation demonstratod that inter-assay and intra-assay coefficient of variation were 4.0% and 5.9% respectively and the mean recovery was 100.5%.The linear range was 0-167.7 U/L.The lowest detection limit was approximately 0 U/L.The interference test showed that there is no significant interferences while the concentration of bilirubin is less than 342 μmoL/L or commonly used anticoagulants is employed at their routine concentrations.However,interference was significant when Hb level is more than 0.06 g/L.Preliminary study of clinical application showed that there was no significant difference of serum ASL level between non-liver disease group and healthy group ( q = 0.027, P = 0.979 ), but there was significant differences for both serum ALT and AST levels (ALT:q =6.461,P =0.000;AST:q =6.481,P =0.000).Conclusions A continuous monitoring assay for the determination of serum ASL activity is successfully established. Serum ASL may be a good biomarker for liver injury.