Poster Presentation HUPO 2019 - 18th Human Proteome Organization World Congress

Determination of total plasma Coenzyme Q10 by liquid chromatography-tandem mass spectrometry to help diagnosis to possible mitochondrial disorder. (#916)

Yi Ling Wong 1 , Wai Yuen Yu 2 , Chun Yiu Law 2 , Ching Wan Lam 1 2
  1. Department of Pathology, University of Hong Kong, Hong Kong, China
  2. Division of Chemical Pathology, Queen Mary Hospital, Hong Kong, China

Background: Coenzyme Q10 (CoQ10), also named ubiquinone is an essential cofactor in the mitochondrial respiratory chain, which is responsible for oxidative phosphorylation. It acts as an electron carrier and an antioxidant in the human body. Endogenous synthesis of CoQ10 is the major source of CoQ10 in human and > 12 genes had been identified in the biosynthetic pathway. Defective CoQ10 biosynthesis could lead to primary CoQ10 deficiency and mitochondrial disorder. In this study, we hypothesize plasma CoQ10 is a biomarker in mitochondrial disorder due to defective CoQ10 synthesis. Since CoQ10 measurement is not universally available, a simple and robust liquid-chromatography tandem mass spectrometry (LC-MS/MS)-based method was introduced and described in this work.

Methods: Test was performed using AB SCIEX 5500 QTRAP coupled with ExionLC™ System. Fresh plasma samples were extracted by protein precipitation using ethanol which included coenzyme Q10-[D9] as an internal standard. 1, 4-benzoquinone was added as an oxidizing agent to convert all reduced form of CoQ10 into the oxidized form for the measurement of total CoQ10. The ammonium adduct ion with MRM transition of 881.0/197.0 was used for quantification.

Results: Our assay showed a linear range of 5-2000 µg/L with R-squared greater than 0.99. The limit of quantification is 10 µg/L in plasma. Accuracy was checked by using commercial plasma QC controls in three different concentrations with less than 5% deviation from target value. The Intra- and inter-assay coefficients of variation were less than 10%. There was no matrix suppression or enhancement in the elution time of CoQ10. The reference range was verified to be 320-1,558 µg/L for age group less than 18 years old and be 433-1532 µg/L for those greater than or equal to 18 years old. A marked reduction in plasma CoQ10 was noted in patients with defective CoQ10 biosynthesis due to COQ4 defect who presented with mitochondriopathy.

Conclusions: This is an efficient and a selective method for determination of CoQ10 concentrations in human plasma for helping diagnosis of CoQ10 deficiency in mitochondrial disorders and monitor its status during treatment.

  1. 1) Miles MV, Horn PS, Tang PH, et al, Clin Chim Acta 2004, 34, 139-144; 2) Claessens AJ, Yeung CK, Risler LJ, Phillips BR, Himmelfarb J, Shen DD, Ann Clin Biochem., 53, 265-273; 3) Quinzii CM, DiMauro S, Hirano M., Neurochem Res., 32, 723-727