Extended use of dried-leukocytes impregnated in filter paper samples for detection of Pompe, Gaucher, and Morquio A diseases

Abstract

Background: Lysosomal storage diseases (LSD) are a group of genetic conditions which could present a vast spectrum of abnormalities that may include skeletal abnormalities, organ dysfunction, neuronal involvement, and tissue accumulation of complex molecules, among other manifestations. Definitive diagnosis of LSD is generally obtained by specific enzyme assays performed in leukocytes, fibroblasts, or more recently, dried-blood filter paper (DBFP) samples.

Methods: We recently introduced dried-leukocytes filter paper (DLFP) as an alternative source of enzyme to assay heparan sulfamidase and galactocerebrosidase activities, which could not be measured in DBFP samples using fluorometric methods. We present a new fluorometric methods on DLFP samples, for evaluation of α-glucosidase (GAA), β-glucosidase (GBA), and N-acetylgalactosamine-6-sulfatase (GALNS) activities, key enzyme assays for the identification of patients with Pompe disease (PD), Gaucher disease (GD), and Morquio A disease (MD), respectively.

Results: We show a clear discrimination between confirmed PD, GD, and MD patients and healthy controls.

Conclusions: We conclude that the assays of GAA, GBA, and GALNS on DLFP are reliable and useful methods for the identification of PD, GD, and MD diseases, respectively. As sample preparation is feasible in standard biochemical laboratories and transportation is very simple, it could enable patients living in remote areas to be investigated, diagnosed and eventually treated with the specific therapies available for these diseases.

Keywords: Dried-leukocytes; Enzyme assay; Gaucher disease; Lysosomal storage diseases; Morquio A disease; Pompe disease.