Rapid diagnosis of maple syrup urine disease in blood spots from newborns by tandem mass spectrometry.
We report a new method for the diagnosis of maple syrup urine disease (MSUD) from dried blood spots on newborn screening cards based on tandem mass spectrometry (MS-MS). The mean +/- SD concentration of Leu plus Ile in normal newborns was 151 +/- 47 mumol/L (n = 1096); for Val, 131 +/- 58 mumol/L (n = 791). SDs were lower when the concentrations of these amino acids were expressed relative to that of Phe. The mean ratio for Leu + Ile to Phe was 2.5 +/- 0.49; for Val to Phe, 2.18 +/- 0.51. These results compare well with values previously reported in the literature. With these criteria, samples from a collection categorized by a bacterial inhibition assay as normal or falsely positive for MSUD were normal by MS-MS [(Leu + Ile): Phe < 5.0]. Samples from confirmed MSUD patients were categorized as abnormal [(Leu+Ile): Phe > 9.0] by MS-MS.
Chace
D H
DH
Department of Pediatrics, Duke University Medical Center, Research Triangle Park, NC 27709.
Hillman
S L
SL
Millington
D S
DS
Kahler
S G
SG
Roe
C R
CR
Naylor
E W
EW
D005189:False Positive Reactions; D006801:Humans; D007231:Infant, Newborn; D007532:Isoleucine / Q000097:blood; D007930:Leucine / Q000097:blood; D008375:Maple Syrup Urine Disease / Q000097:blood*; D013058:Mass Spectrometry / Q000379:methods* / Q000706:statistics & numerical data; D015997:Neonatal Screening / Q000379:methods*; D010209:Paper; D010649:Phenylalanine / Q000097:blood; D012016:Reference Values; D012680:Sensitivity and Specificity; D014633:Valine / Q000097:blood
D007532:Isoleucine; D010649:Phenylalanine; D007930:Leucine; D014633:Valine