An automated clinical mass spectrometric method for identification and quantification of variant and wild‐type amyloid‐β 1‐40 and 1‐42 peptides in CSF

INTRODUCTION: We developed an automated liquid chromatography‐tandem mass spectrometry high performance liquid chromatography tandem mass spectrometry (HPLC‐MS/MS) method for multiplex quantification of wild‐type (wt) amyloid β (Aβ) peptides 1‐40 (Aβ40) and 1‐42 (Aβ42) and detection of variant Aβ peptides in cerebrospinal fluid. METHODS: The multiplex Aβ HPLC‐MS/MS assay was validated in a clinically accredited laboratory following regulatory guidelines, with Aβ42 calibration assigned to the ERM/IFCC certified reference material; sequence variants were additionally multiplexed into the method. RESULTS: Sample preparation was fully automated on a liquid handler. The assay quantified wt‐Aβ42 and wt‐Aβ40 and detected sequence variants, when present, within the Aβ42 sequence. DISCUSSION: Extension of the HPLC‐MS/MS approach for quantification of wt‐Aβ42 and wt‐Aβ40 to include known sequence variants increases analytical accuracy of the mass spectrometric approach and enables identification of cases of autosomal dominant Alzheimer's disease. Development of an automated workflow and selection of appropriate instrumentation enabled deployment of this method in routine clinical testing.