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

IntroductionWe 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 beta (A beta) peptides 1-40 (A beta 40) and 1-42 (A beta 42) and detection of variant A beta peptides in cerebrospinal fluid. MethodsThe multiplex A beta HPLC-MS/MS assay was validated in a clinically accredited laboratory following regulatory guidelines, with A beta 42 calibration assigned to the ERM/IFCC certified reference material; sequence variants were additionally multiplexed into the method. ResultsSample preparation was fully automated on a liquid handler. The assay quantified wt-A beta 42 and wt-A beta 40 and detected sequence variants, when present, within the A beta 42 sequence. DiscussionExtension of the HPLC-MS/MS approach for quantification of wt-A beta 42 and wt-A beta 40 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.