35. Setting-Up a LC-MS/MS Method Coupled to an Automatic On-Line Sample Clean-Up for a Multiplex Lysosomal Storage Disorders Screening
Poster: Mon 2:00-3:00PM
Bruno Casetta
AB Sciex
Bruno Casetta, AB SCIEX Monza (Italy)
The Lysosomal Storage Disorders (LSD) are a heterogeneous group of over 40 inherited genetic disorders, each of them centred on a total or partial defect of a specific enzymatic activity.

Gelb’s group has demonstrated as many lysosomal enzymes are still active in re-hydrated dried blood spots (DBS), the same spots used for the "classical" Neonatal screening (Clinical Chemistry 50:10 1785–1796 (2004)).

The presented approach partially replicates the enzyme activation protocol as proposed by Gelb’s group but by eliminating any sample manipulation between the incubation and the mass spectrometric measurement through the implementation of an automated on-line Sample Extraction and Clean-up in front of the mass-spectrometer. This approach enables the simultaneous screening for five different LSD disorders (Fabry, Pompe, Niemann-Pick, Krabbe, Gaucher) in a single LC-MS/MS run.

With the proposed protocol, 200 samples can be measured in less than 14 hours and sample manipulation is limited to the incubation activation, being skipped any further manipulation before the tandem mass spectrometer measurement.

With a LOD between 0.04 and 0.30 µmol/h/L as enzymatic activity for each disorder, the inter-day precision measured on normal patients has been between 5 % (pertaining the Fabry disorder) and 15 % (pertaining the Niemann-Pick disorder).