Newborn screening for hepatorenal tyrosinemia by tandem mass spectrometry: analysis of succinylacetone extracted from dried blood spots.
OBJECTIVE
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.
Allard
Pierre
P
Division of Genetics, Tufts-New England Medical Center, and Tufts University School of Medicine, Boston, MA 02111, USA. pierre.allard.hsj@ssss.gouv.qc.ca
Grenier
André
A
Korson
Mark S
MS
Zytkovicz
Thomas H
TH
D006537:Heptanoates / Q000097:blood* / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D013058:Mass Spectrometry; D015997:Neonatal Screening / Q000379:methods*; D020176:Tyrosinemias / Q000175:diagnosis* / Q000378:metabolism
D006537:Heptanoates; C020804:succinylacetone