Search

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.

in filter paper, initially for the detection of heparan sulfamidase (MPS IIIA) and beta-galactosidase (GM1-gangliosidosis, MPS IVB, galactosialidosis) deficiencies. We prepared filter paper samples with dried-leukocytes or dried-fibroblast (DLFP, DFFP) from healthy individuals and from patients with confirmed MPS IIIA or GM1 gangliosidosis by direct transfer of cell homogenates to filter paper discs. Heparan sulfaminidase and beta-galactosidase were tested by incubating samples with specific buffers and substrates. For heparan sulfamidase, a clear discrimination was found between normal controls and MPS IIIA patients both in DLFP and DFFP samples. For beta-galactosidase, distinction between normal controls and GM1-gangliosisdosis patients was evidenced only in DLFP samples so far. Although the method still needs further development, we conclude that assays for these two enzymes could be performed in dried-cell homogenates, and could be an useful tool for LSD identification, especially in areas where liquid blood samples usually need to travel several days to reach the reference laboratory.