Urine acylcarnitine analysis by ESI-MS/MS: a new tool for the diagnosis of peroxisomal biogenesis disorders.
BACKGROUND
Patients with peroxisomal biogenesis disorders (PBDs) have an abnormal profile of circulating acylcarnitines (i.e. elevated C16:0-DC-, C18:0-DC-, C24:0-, C26:0-carnitine). We developed an ESI-MS/MS method for quantification of urine acylcarnitines and tested its reliability for the diagnosis of PBDs.


METHODS
Urine from 7 patients with PBDs (5 Zellweger syndrome, 2 infantile Refsum disease), from 2 patients with D-bifunctional protein (D-BP) deficiency, and from 130 healthy controls were analysed by ESI-MS/MS, using a multiple reactions monitoring (MRM) method, and quantified with labelled internal standards. Acylcarnitine levels between groups were analyzed by the STATA statistics data analysis and compared by the non parametric Mann-Whitney test.


RESULTS
In PBDs, the urinary excretion of long-chain dicarboxylylcarnitines (C14:0-DC-, C16:0-DC-, and C18:0-DC-carnitine), and of very long-chain monocarboxylylcarnitines (C22:0-, C24:0-, C26:0-carnitine) were significantly elevated compared to controls (p<0.0001). Interestingly, among PBDs the most severe abnormalities of acylcarnitine profile were observed in patients with Zellweger syndrome. One patient with D-BP showed similar abnormalities to PBDs, while in the other only C16:0-DC-carnitine was markedly elevated.


CONCLUSIONS
This study shows that MRM ESI-MS/MS acylcarnitine analysis unequivocally discriminates patients with PBDs and D-BP deficiency from controls, representing a reliable and sensitive method for the diagnosis that requires a short-time analysis with high sample through-put.
Duranti
Guglielmo
G
Division of Metabolism, Bambino Gesù Research Institute, Piazza S. Onofrio 4, 00165 Rome, Italy.
Boenzi
Sara
S
Rizzo
Cristiano
C
Ravà
Lucilla
L
Di Ciommo
Vincenzo
V
Carrozzo
Rosalba
R
Meschini
Maria Chiara
MC
Johnson
David W
DW
Dionisi-Vici
Carlo
C
D002331:Carnitine / Q000031:analogs & derivatives* / Q000652:urine; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D018901:Peroxisomal Disorders / Q000175:diagnosis* / Q000652:urine*; D012035:Refsum Disease / Q000175:diagnosis / Q000652:urine; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D015211:Zellweger Syndrome / Q000175:diagnosis / Q000652:urine
C116917:acylcarnitine; D002331:Carnitine