Searching, Structural Determination, and Diagnostic Performance Evaluation of Biomarker Molecules for Niemann–Pick Disease Type C Using Liquid Chromatography/Tandem Mass Spectrometry

Abstract

Niemann–Pick disease type C (NPC) is an autosomal recessive disorder that is characterized by progres-sive neuronal degeneration. Patients with NPC have a wide age of onset and various clinical symptoms. Therefore, the discovery and diagnosis of NPC are very difficult. Conventional laboratory tests are com-plicated and time consuming. In this context, biomarker searches have recently been performed. Our research group has previously also investigated NPC biomarkers based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) and related techniques. To identify biomarker candidates, nontargeted analysis with high-resolution MS and MS/MS scanning is commonly used. Structural speculation has been performed using LC/MS/MS fragmentation and chemical derivatization, while identification is performed by matching authentic standards and sample specimens. Diagnostic performance evaluation was performed using the validated LC/MS/MS method and analysis of samples from patients and control subjects. NPC biomarkers, which have been identified and evaluated in terms of performance, are various classes of lipid molecules. Oxysterols, cholenoic acids, and conjugates are cholesterol-derived molecules detected in the blood or urine. Plasma lyso-sphingolipids are biomarkers for both NPC and other lysosomal diseases. N-palmitoyl-O-phosphocholine-serine is a novel class of lipid biomarkers for NPC. This article reviews biomarkers for NPC and the analysis methods employed to that end.