Abstract
BACKGROUND: Clinical presentation and disease severity in
disorders of purine and pyrimidine metabolism vary
considerably. We present a method that allows
comprehensive, sensitive, and specific diagnosis of the
entire spectrum of abnormalities in purine and pyrimidine
metabolism in 1 analytical run. METHODS: We used
reversed-phase HPLC electrospray ionization tandem mass
spectrometry to investigate 24 metabolites of purine and
pyrimidine metabolism in urine samples from healthy persons
and from patients with confirmed diagnoses of inherited
metabolic disorders. Urine samples were filtered and
diluted to a creatinine concentration of 0.5 mmol/L.
Stable-isotope-labeled internal standards were used for
quantification. The metabolites were analyzed by
multiple-reaction monitoring in positive and negative
ionization modes. RESULTS: Total time of analysis was 20
min. Recovery (n = 8) of a compound after addition of a
known concentration was 85\%-133\%. The mean intraday
variation (n = 10) was 12\%. The interday variation (n = 7)
was < or =17\%. Age-related reference intervals were
established for each compound. Analysis of patient urine
samples revealed major differences in tandem mass
spectrometry profiles compared with those of control
samples. Twelve deficiencies were reliably detected:
hypoxanthine guanine phosphoribosyl transferase, xanthine
dehydrogenase, purine nucleoside phosphorylase,
adenylosuccinate lyase, uridine monophosphate synthase,
adenosine deaminase, adenine phosphoribosyl transferase,
molybdenum cofactor, thymidine phosphorylase,
dihydropyrimidine dehydrogenase, dihydropyrimidinase, and
beta-ureidopropionase. CONCLUSION: This method enables
reliable detection of 13 defects in purine and pyrimidine
metabolism in a single analytical run.
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