1H NMR spectra of methylcitric acid in urine.

Methylcitric acid (3-carboxy-3-hydroxy-2-methyl-pentanedioic acid; MCA) is elevated in body fluids of patients with propionic acidaemia (PA; McKusick: 232000, 232050), methylmalonic aciduria (MMA; McKusick: 251000, 251120) and multiple carboxylase deficiency (McKusick: 253260, 253270). MCA molecule has two stereogenic centers so that it can occur in the form of four stereoisomers. Only two stereoisomers of MCA, (2S, 3S) and (2R, 3S), were found in human urine. They have different spectra and can be easily distinguished. We performed measurements of 1H, 13C NMR and gs-HMQC (gradient-selected Heteronuclear Multiple Quantum Coherence) on the samples of unprocessed urine of 6 patients suffering from propionic acidaemia and methylmalonic aciduria and identified the protons of MCA diastereoisomers, 3-hydroxypropionic acid and methylmalonic acid. Having used NMR spectroscopy to identify stereoisomers of MCA in urine, we can conclude that this technique gives the possibility of analysing MCA diastereoisomers in body fluids.

Absolute configuration of N-acetylaspartate in urine from patients with Canavan disease.

High-resolution 1H and 13C NMR of N-acetylaspartic acid as its 2-(S)-butyl diester allows the two enantiomers to be unambiguously identified. Analysis of urine samples from five patients with Canavan disease (N-aspartoacylase deficiency) showed that more than 95% of the excreted N-acetylaspartate had the S-configuration.

Trial of erythropoietin treatment in a boy with glutathione synthetase deficiency.

We report a 3-year-old boy with glutathione synthetase deficiency, who in the newborn period developed severe persistent haemolytic anaemia. Treatment with erythropoietin was introduced with good clinical and haematological response.

13C NMR spectroscopy: a convenient tool for detection of argininosuccinic aciduria.

Proton decoupled high resolution 13C NMR spectra of argininosuccinic acid have been measured in a series of dilute water solutions of various acidity. These data have provided a basis for unequivocal determination of the presence of this metabolite in the investigated sample. The method additionally enables simultaneous rough estimation of the metabolite concentration. In order to check the practicability of the usage of this spectroscopy for diagnostic purposes, the spectra of several unprocessed urine samples have been recorded including three from patients with argininosuccinic aciduria. It has been concluded that 13C NMR spectroscopy can be a convenient method of recognising the above syndrome and probably many other inborn metabolic errors which manifest themselves with the excretion of the marker metabolite in amounts comparable to (or larger than) creatinine.

Further delineation of the classical Smith-Lemli-Opitz syndrome phenotype at different patient ages: clinical and biochemical studies.

We present here extensive clinical and biochemical data on thirteen SLOS (type I) patients with proven defect in cholesterol biosynthesis for further delineation of the classical SLOS phenotype at different patient ages.

N-acetylaspartylglutamate in Canavan disease: an adverse effector?

UNLABELLED: We measured N-acetylaspartate and its precursor/product N-acetylaspartylglutamate (NAAG) in urine of patients with Canavan disease using capillary zone electrophoresis. Abnormal levels of NAAG were found in 32 of 43 patients examined. Elevated NAAG was also present in the CSF of one patient. Given that NAAG may interfere with N-methyl-D-aspartate receptor function, the occurrence of high levels of NAAG in patients' urine conceivably represents a participating factor in the pathogenesis of Canavan disease. CONCLUSION: The biochemical role of N-acetylaspartylglutamate and its relationship to glutamatergic function may be relevant to the pathogenesis of Canavan disease.