Measurement of succinyl-carnitine and methylmalonyl-carnitine on dried blood spot by liquid chromatography-tandem mass spectrometry

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• 作者：Cristiano Rizzo ; Sara Boenzi ; Rita Inglese ; Giancarlo la Marca ; Maurizio Muraca ; Tegra Barreiro Martinez ; David W. Johnson ; Eleonora Zelli ; Carlo Dionisi-Vici
• 关键词：MMAs ; Methylmalonic acidurias ; SCS ; succinyl-CoA synthetase ; C3-C ; propionyl-carnitine ; C4DC-C ; C4-dicarboxylyl-carnitine ; C3-C/C2-C ; propionyl-carnitine/acetyl-carnitine ratio ; C3-C/C16-C ; propionyl-carnitine/palmitoyl-carnitine ratio ; MS/MS ; tandem mass spectrometry ; SC ; succinyl-carnitine ; MMC ; methylmalonyl-carnitine ; TDHFA ; tridecafluoroheptanoic acid ; FOA ; formic acid ; DP ; declustering potential ; CXP ; collision cell exit potential ; CE ; collision energy ; LOD ; limit of detection ; LLOQ ; lower
• 刊名：Clinica Chimica Acta
• 出版年：15 February, 2014
• 年：2014
• 卷：429
• 期：Complete
• 页码：30-33
• 全文大小：293 K

文摘

Methylmalonic aciduria (MMA) is one of the most frequent organic acidurias, a class of diseases caused by enzymatic defects mainly involved in the catabolism of branched-chain amino acids. Recently, mild MMA and C4-dicarboxylyl-carnitine (C4DC-C) accumulation have been reported in patients carrying mutation in genes encoding the 伪-subunit (SUCLG1) and the 尾-subunit (SUCLA2) of the ADP-forming succinyl-CoA synthetase (SCS).

We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify in dried blood spot the two isobaric compounds of C4DC-C, succinyl-carnitine and methylmalonyl-carnitine, to allow the differential diagnosis between classical MMA and SCS-related defects.

This method, with an easy liquid-phase extraction and derivatization procedure, has been validated to demonstrate the specificity, linearity, recovery, lowest limit of quantification (LLOQ), accuracy and precision for quantitative determination of blood succinyl-carnitine and methylmalonyl-carnitine. The assay was linear over a concentration range of 0.025-10 渭mol/L and achieved the LLOQ of 0.025 渭mol/L for both metabolites.

The average slope, intercept, and coefficient of linear regression (r²) were respectively: 0.3389 (95% confidence interval 0.2888-0.3889), 0.0113 (95% confidence interval 鈭?#xA0;0.0157 to 0.0384), 0.9995 (95% confidence interval 0.9990-1.0000) for succinyl-carnitine and 0.5699 (95% confidence interval 0.5263-0.6134), 0.0319 (95% confidence interval 鈭?#xA0;0.0038 to 0.0677), 0.9997 (95% confidence interval 0.9995-1.0000) for methylmalonyl-carnitine. Within-day and between-day coefficients of variation (CV) were 1.94% and 3.19% for succinyl-carnitine and 3.21%, and 2.56 for methylmalonyl-carnitine.

This method is accurate and provides a new tool to differentiate patients with classical methylmalonic acidemia from those with SCS-related defects.