hexanoylcarnitine and propionic-acid

We applied untargeted mass spectrometry-based metabolomics to the diseases methylmalonic acidemia (MMA) and propionic acidemia (PA).. We used a screening platform that used untargeted, mass-based metabolomics of methanol-extracted plasma to find significantly different molecular features in human plasma samples from MMA and PA patients and from healthy individuals. Capillary reverse phase liquid chromatography (4 microL/min) was interfaced to a TOF mass spectrometer, and data were processed using nonlinear alignment software (XCMS) and an online database (METLIN) to find and identify metabolites differentially regulated in disease.. Of the approximately 3500 features measured, propionyl carnitine was easily identified as the best biomarker of disease (P value 1.3 x 10(-18)), demonstrating the proof-of-concept use of untargeted metabolomics in clinical chemistry discovery. Five additional acylcarnitine metabolites showed significant differentiation between plasma from patients and healthy individuals, and gamma-butyrobetaine was highly increased in a subset of patients. Two acylcarnitine metabolites and numerous unidentified species differentiate MMA and PA. Many metabolites that do not appear in any public database, and that remain unidentified, varied significantly between normal, MMA, and PA, underscoring the complex downstream metabolic effects resulting from the defect in a single enzyme.. This proof-of-concept study demonstrates that metabolomics can expand the range of metabolites associated with human disease and shows that this method may be useful for disease diagnosis and patient clinical evaluation.

Topics: Acetylcarnitine; Adult; Amino Acid Metabolism, Inborn Errors; Betaine; Biomarkers; Carnitine; Child; Chromatography, High Pressure Liquid; Humans; Methylmalonic Acid; Plasma; Propionates; Spectrometry, Mass, Electrospray Ionization

This paper describes a method for the quantitative determination of free carnitine, acetylcarnitine, propionylcarnitine, hexanoylcarnitine, octanoylcarnitine, and total carnitine in plasma. Carnitine and acylcarnitines were extracted from 100 microliters of plasma with acetonitrile/methanol and isolated using 0.5-ml columns of silica gel. Samples were then derivatized with 4'-bromophenacyl trifluoromethanesulfonate and quantified by high-performance liquid chromatography with detection at 260 nm. Carnitine and acylcarnitines were quantified in normal human plasma and the plasma of patients diagnosed with methylmalonic aciduria, propionic acidemia, and medium-chain acyl-CoA dehydrogenase deficiency.

Topics: Acetylcarnitine; Acyl-CoA Dehydrogenase; Acyl-CoA Dehydrogenases; Acylation; Carnitine; Chromatography, High Pressure Liquid; Humans; Methylmalonic Acid; Molecular Weight; Propionates; Reference Standards; Reproducibility of Results