Rapid detection of argininosuccinic aciduria and citrullinuria by fast atom bombardment and tandem mass spectrometry

How mass spectrometry revolutionized newborn screening

This article offers a personal account of a remarkable journey spanning over 30 years of applied mass spectrometry in a clinical setting. It begins with the author's inspiration from a clinician's story of rescuing a child from near death with a revolutionary therapeutic intervention. Motivated by this experience, the author delved into the field of chemistry and mass spectrometry to solve an analytical challenge. The breakthrough came with the development of the first front-line diagnostic test performed by MS/MS, which focused on analyzing acylcarnitines to detect and diagnose inherited disorders related to fatty acid and branched-chain amino acid catabolism. Building upon this success, the author expanded the application of the method to dried blood spots, incorporating additional analytical components such as essential amino acids. The result was a groundbreaking multiplex assay capable of screening newborns for more than 30 inherited metabolic conditions with just one test. This novel approach laid the foundation for a targeted metabolomics platform that facilitated the identification of new animal models of metabolic disease through screening the offspring of genetically modified adults. The development and utilization of MS/MS with UPLC has led to the creation of new assays for biomarkers of metabolic disease, benefiting both the diagnosis and therapeutic monitoring of these conditions. The article provides compelling examples from the author's laboratory, highlighting the value and vast applications of these methods in the field of metabolic disease research.

Marking of metabolites in the diagnostics of metabolic diseases and in the investigation of xenobiotics metabolism using NMR spectroscopy

There are currently no sound estimates of the number of children born with a serious congenital disorder attributable to genetic or environmental causes (World Health Organization) but there is a supposed number of babies born with birth defects per year: in the world approximately 7.9 million children (6% of births). There is conducted population-based screening by the individual countries. The specialised methods are used when it is not possible to diagnose disease in screening. In recent years in the diagnostics of these disorders the methods of Magnetic Resonance Spectroscopy of the brain (in vivo¹H-MRS) and high resolution NMR spectroscopy gain in importance. The manuscript focused on developing the method of marking the metabolic diseases markers of various origins using NMR spectroscopy (including synthesis of markers). Considering the disorders occurring among children, according to Hoffman, Zschocke, Nyhan, there are three following groups of inherited metabolic diseases: disorders of intermediary metabolism, disorders of the biosynthesis and breakdown of complex molecules and neurotransmitter defects and related disorders. The presented investigation is focused on: a study of selected compounds that cause disorders of intermediary metabolism, a study of compounds that cause disorders of the biosynthesis and breakdown of complex molecules and a study of compounds that cause neurotransmitter defects and related disorders. In the subsequent chapter of manuscript there are presented the results of investigation concerning the metabolism of xenobiotics that could potentially be used in therapy of inherited metabolic diseases, basing on stilbene derivatives. In the last chapter there are presented the results of experiments with creatinine- the metabolite produced in muscles.

Fetal fatty acid oxidation disorders, their effect on maternal health and neonatal outcome: impact of expanded newborn screening on their diagnosis and management

Mitochondrial fatty acid oxidation disorders (FAOD) are recessively inherited errors of metabolism. Newborns with FAOD typically present with hypoketotic hypoglycemia, metabolic acidosis, hepatic failure, and cardiomyopathy. Late presentations include episodic myopathy, neuropathy, retinopathy, and arrhythmias. Sudden unexpected death can occur at any age and can be confused with sudden infant death syndrome. Some FAOD are associated with intrauterine growth restriction, prematurity, and pregnancy complications in the heterozygous mother, such as severe preeclampsia, acute fatty liver of pregnancy (AFLP), or hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome. Maternal pregnancy complications occur primarily in mothers carrying a fetus with long-chain l-3-hydroxyacyl CoA dehydrogenase deficiency or general trifunctional protein deficiencies. FAOD as a group represent the most common inborn errors of metabolism, and presymptomatic diagnosis of FAOD is the key to reduce morbidity and avoid mortality. The application of tandem mass spectrometry to newborn screening provides an effective means to identify most FAOD patients presymptomatically. At the beginning of 2005, 36 state newborn screening programs have mandated or adopted this technology resulting in a marked increase in the number of asymptomatic neonates with FAOD diagnosed. To ensure the long-term benefits of such screening programs, pediatricians and other health care providers must be educated about these disorders and their treatment.

ESI-MS/MS analysis of underivatised amino acids: a new tool for the diagnosis of inherited disorders of amino acid metabolism. Fragmentation study of 79 molecules of biological interest in positive and negative ionisation mode

The diagnosis of inherited disorders of amino acids (AA) metabolism is usually performed on automated analysers by ion-exchange chromatography and quantification after ninhydrin derivatisation of about 50 different AA. A single run liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for these molecules can be an alternative to this time-consuming technique. The first step of this development is the infusion study of the fragmentation of 79 molecules of biological interest in electrospray ionisation tandem mass spectrometry (ESI-MS/MS), in positive and in negative ionisation mode. Among them, three molecules can be detected only in negative ionisation mode, 38 only in positive mode and 38 in the two modes. All the most abundant fragmentations are presented, with optimisation of the MS/MS parameters. The positive ionisation mode was retained for the simultaneous analysis of 76 molecules. One sensitive and/or specific transition is proposed for the monitoring of each molecule. Improvement in sensitivity of detection was obtained with the use of an acidic mobile phase. Flow injection analysis studies led us to highlight a number of interferences-due to isobaric molecules, to in-source collision-induced dissociation, or to natural isotopic distribution of the elements-which are listed. For a reliable quantification method, these molecules have to be separated by LC before analysis in the tandem mass spectrometer. Ion-pairing reversed-phase liquid chromatography (RPLC) using perfluorinated carboxylic acids as ion-pairing agents has already been found suitable for analysis of AA in MS/MS positive ionisation mode and is under development.

Diagnosis and monitoring of inborn errors of metabolism using urease-pretreatment of urine, isotope dilution, and gas chromatography-mass spectrometry

To diagnose inborn errors of metabolism, it would be desirable to simultaneously analyze and quantify organic acids, purines, pyrimidines, amino acids, sugars, polyols, and other compounds using a single-step fractionation; unfortunately, no such method currently exists. The present article will be concerned primarily with a practical yet comprehensive diagnostic procedure of inborn errors of metabolism (IEM). This procedure involves the use of urine or eluates from urine on filter paper, stable isotope dilution, and gas chromatography-mass spectrometry (GC-MS). This procedure not only offers reliable and quantitative evidence for diagnosing, understanding and monitoring the diseases, but also provides evidence for the diagnosis of new kinds of IEM. In this review, the differential diagnosis for hyperammonemia are described; deficiencies of ornithine carbamoyl transferase, argininosuccinate synthase (citrullinemia), argininosuccinate lyase and arginase, lysinuric protein intolerance, hyperammonemia-hyperornithinemia-homocitrullinemia syndrome, and citrullinemia type II. The diagnosis of IEM of purine and pyrimidine such as deficiencies of hypoxanthine-guanine phosphoribosyl transferase, adenine phosphoribosyl transferase, dihydropyrimidine dehydrogenase, dihydropyrimidinase and beta-ureidopropionase are described. During the pilot study for newborn screening, we found neonates with diseases at a rate of 1 per 1,400 including propionic acidemia, methylmalonic acidemia, orotic aciduria, beta-ureidopropionase deficiency, lactic aciduria and neuroblastoma. A rapid and reliable prenatal diagnosis for propionic acidemia is also described.

Mass spectrometry methods for metabolic and health assessment

Beginning in the mid 1960s, mass spectrometry was introduced in a few academic laboratories for the analysis of organic acids by gas chromatography-mass spectrometry. Since then, multiple-stage mass spectrometers have become available and many new applications have been developed. Major advantages of these new techniques include their ability to rapidly determine many different compounds in complex biological matrices with high sensitivity and in sample volumes of usually < 100 microL. A high sample throughput is further realized because extensive sample preparations are often not necessary. However, because the technical know-how is not yet widely available and significant experience is required for correct interpretation of results, these methods are being implemented slowly in routine clinical laboratories as opposed to research laboratories. Several of these new applications are considered with regard to clinical medicine.