PMID- 34820666 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20211126 IS - 2667-145X (Electronic) IS - 2667-1468 (Print) IS - 2667-145X (Linking) VI - 20 DP - 2021 Apr TI - Analysis of 2-methylcitric acid, methylmalonic acid, and total homocysteine in dried blood spots by LC-MS/MS for application in the newborn screening laboratory: A dual derivatization approach. PG - 1-10 LID - 10.1016/j.jmsacl.2021.03.001 [doi] AB - Inborn errors of propionate, cobalamin and methionine metabolism are targets for Newborn Screening (NBS) in most programs world-wide, and are primarily screened by analyzing for propionyl carnitine (C3) and methionine in dried blood spot (DBS) cards using tandem mass spectrometry (MS/MS). Single-tier NBS approaches using C3 and methionine alone lack specificity, which can lead to an increased false-positive rate if conservative cut-offs are applied to minimize the risk of missing cases. Implementation of liquid chromatography tandem mass spectrometry (LC-MS/MS) second-tier testing for 2-methylcitric acid (MCA), methylmalonic acid (MMA), and homocysteine (HCY) from the same DBS card can improve disease screening performance by reducing the false-positive rate and eliminating the need for repeat specimen collection. However, DBS analysis of MCA, MMA, and HCY by LC-MS/MS is challenging due to limited specimen size and analyte characteristics leading to a combination of low MS/MS sensitivity and poor reverse-phase chromatographic retention. Sufficient MS response and analytical performance can be achieved for MCA by amidation using DAABD-AE and by butylation for MMA and HCY. Herein we describe the validation of a second-tier dual derivatization LC-MS/MS approach to detect elevated MCA, MMA, and HCY in DBS cards for NBS. Clinical utility was demonstrated by retrospective analysis of specimens, an interlaboratory method comparison, and assessment of external proficiency samples. Imprecision was <10.8% CV, with analyte recoveries between 90.2 and 109.4%. Workflows and analytical performance characteristics of this second-tier LC-MS/MS approach are amenable to implementation in the NBS laboratory. CI - (c) 2021 THE AUTHORS. Publishing services by ELSEVIER B.V. on behalf of MSACL. FAU - Dubland, Joshua A AU - Dubland JA AD - Department of Pathology and Laboratory Medicine, British Columbia Children's Hospital, Vancouver, BC, Canada. AD - British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada. AD - Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada. FAU - Rakic, Bojana AU - Rakic B AD - Department of Pathology and Laboratory Medicine, British Columbia Children's Hospital, Vancouver, BC, Canada. AD - British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada. AD - Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada. FAU - Vallance, Hilary AU - Vallance H AD - Department of Pathology and Laboratory Medicine, British Columbia Children's Hospital, Vancouver, BC, Canada. AD - British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada. AD - Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada. FAU - Sinclair, Graham AU - Sinclair G AD - Department of Pathology and Laboratory Medicine, British Columbia Children's Hospital, Vancouver, BC, Canada. AD - British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada. AD - Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada. LA - eng PT - Journal Article DEP - 20210317 PL - Netherlands TA - J Mass Spectrom Adv Clin Lab JT - Journal of mass spectrometry and advances in the clinical lab JID - 101776811 PMC - PMC8601015 OTO - NOTNLM OT - 2-Methylcitric acid OT - C2, acetylcarnitine OT - C3, propionylcarnitine OT - CBS, cystathionine beta-synthase OT - Cbl, cobalamin OT - DAABD-AE, 4-[2-(N,N-dimethylamino)ethylaminosulfonyl]-7-(2-aminoethylamino)-2,1,3-benzoxadiazole OT - DBS, dried blood spot OT - DMAP, 4-(dimethylamino)pyridine OT - DTT, dithiothreitol OT - EDC, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride OT - ESI, electrospray ionization OT - FA, formic acid OT - GC, gas chromatography OT - GPCho's, glycerophosphocholines OT - HCY, homocysteine OT - HCl, hydrochloric acid OT - Homocysteine OT - LC, liquid chromatography OT - LLOD, lower limit of detection OT - LLOQ, lower limit of quantitation OT - MCA, 2-methylcitric acid OT - MMA, methylmalonic acid OT - MPs, mobile phases OT - MRM, multiple reaction monitoring OT - MS, mass spectrometry OT - MS/MS, tandem mass spectrometry OT - Mass spectrometry OT - Met, methionine OT - Methylmalonic acid OT - NBS, newborn screening OT - Newborn screening OT - PPV, positive predictive value OT - Phe, phenylalanine OT - QC, quality control OT - S/N, signal-to-noise OT - Second-tier OT - rpm, revolutions per minute COIS- The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. EDAT- 2021/11/26 06:00 MHDA- 2021/11/26 06:01 PMCR- 2021/03/17 CRDT- 2021/11/25 06:43 PHST- 2020/11/23 00:00 [received] PHST- 2021/03/01 00:00 [revised] PHST- 2021/03/03 00:00 [accepted] PHST- 2021/11/25 06:43 [entrez] PHST- 2021/11/26 06:00 [pubmed] PHST- 2021/11/26 06:01 [medline] PHST- 2021/03/17 00:00 [pmc-release] AID - S2667-145X(21)00006-7 [pii] AID - 10.1016/j.jmsacl.2021.03.001 [doi] PST - epublish SO - J Mass Spectrom Adv Clin Lab. 2021 Mar 17;20:1-10. doi: 10.1016/j.jmsacl.2021.03.001. eCollection 2021 Apr.