OBJECTIVES: To develop a method for the determination of succinylacetone (SA) in dried blood spots (DBS) using tandem mass spectrometry (MS/MS). METHODS: SA was extracted from DBS with an acetonitrile and water solution (80:20 by volume) containing formic acid and hydrazine hydrate (both at 0.1% by volume), and analyzed by MS/MS with a total run time per sample under 2 min. The reference range for SA in newborns was determined by analyzing a control group of 3199 DBS. SA was also measured in stored newborn specimens from three patients diagnosed clinically with hepatorenal tyrosinemia (HT). RESULTS: The within-run precision was <or=7.4% and total precision was <or=12.2% on blood spots fortified with SA at 2, 10, and 50 micromol/L. The limit of quantitation was 1 micromol/L and the calibration was linear from 1 to 50 micromol/L. A comparison of SA analysis of this MS/MS method with an established enzyme assay indirectly quantitating SA by inhibition of delta-aminolevulinic acid dehydratase demonstrated a strong correlation. The reference range in the control group of unaffected newborn was determined to be <2 micromol/L, while SA in retrieved DBS from HT patients was significantly elevated, measuring 46.7, 36.5, and 23.2 micromol/L. CONCLUSIONS: We report a simple method that can be used for screening HT in newborns. Based on our limited experience, a 2 micromol/L cutoff could result in up to 100% sensitivity and specificity.
OBJECTIVES: To develop a method for the determination of succinylacetone (SA) in dried blood spots (DBS) using tandem mass spectrometry (MS/MS). METHODS:SA was extracted from DBS with an acetonitrile and water solution (80:20 by volume) containing formic acid and hydrazine hydrate (both at 0.1% by volume), and analyzed by MS/MS with a total run time per sample under 2 min. The reference range for SA in newborns was determined by analyzing a control group of 3199 DBS. SA was also measured in stored newborn specimens from three patients diagnosed clinically with hepatorenal tyrosinemia (HT). RESULTS: The within-run precision was <or=7.4% and total precision was <or=12.2% on blood spots fortified with SA at 2, 10, and 50 micromol/L. The limit of quantitation was 1 micromol/L and the calibration was linear from 1 to 50 micromol/L. A comparison of SA analysis of this MS/MS method with an established enzyme assay indirectly quantitating SA by inhibition of delta-aminolevulinic acid dehydratase demonstrated a strong correlation. The reference range in the control group of unaffected newborn was determined to be <2 micromol/L, while SA in retrieved DBS from HT patients was significantly elevated, measuring 46.7, 36.5, and 23.2 micromol/L. CONCLUSIONS: We report a simple method that can be used for screening HT in newborns. Based on our limited experience, a 2 micromol/L cutoff could result in up to 100% sensitivity and specificity.
Authors: Víctor R De Jesús; Barbara W Adam; Daniel Mandel; Carla D Cuthbert; Dietrich Matern Journal: Mol Genet Metab Date: 2014-07-17 Impact factor: 4.797