Easy method for newborn screening of six lysosomal storage disorders using online solid-phase extraction with mass spectrometry

Abstract

Objective: A modified method for screening of six lysosomal storage disorders (LSDs) by tandem mass spectrometry was presented. Methods: The enzyme activities for six LSDs (Gaucher, Pompe, Krabbe, Fabry, Niemann-Pick A/B and Mucopolysaccharidosis Type I) was measured by using ultra-HPLC and mass spectrometry. After overnight incubation of dried blood spots with three distinct reaction cocktails containing substrates and internal standards, reactions were stopped and online trapping was performed with ultra-HPLC preceding to mass spectrometry. Ultra-HPLC was equipped with online solid phase extraction and Hypersil Gold C8 analytical columns and coupled with TSQ Quantum Access Max mass spectrometry. Results: Activities of acid-ss-glucocerebrosidase (ABG), acid glucosidase (GAA), galactocerebroside-ss-galactosidase (GALC), acid-galactosidase A (GLA), acid sphingomyelinase (ASM), and alpha-L-iduronidase (IDU) were obtained from DBSs of patients and healthy individuals. The intra- and inter-assay precisions were <20\% (CV). Conclusion: Our modified method, needing less DBS punches and only three reaction coctails, with the online trapping methodology, accurately differentiates newborns with LSDs from healthy newborns.