title: Rapid diagnostic testing procedures for lysosomal storage disorders: alpha-glucosidase and beta-galactosidase assays on dried blood spots.
abstract: BACKGROUND
  Lysosomal storage disorders (LSDs) are pathologies caused by the deficit of lysosomal enzymes; late diagnosis may render therapeutic programs less effective. As early, pre-symptomatic detection could change the natural history of the disease, we are setting up rapid microassays using dried blood spots (DBS) on filter paper. Here we report alpha-glucosidase and beta-galactosidase assays.
  
  
  METHODS
  Enzymatic activities were evaluated on DBS from five different groups of subjects including healthy controls and patients affected with an LSD. A 260-day monitoring of DBS preservation at five different temperatures and a comparison of the enzymatic activities measured in DBS obtained from a single (sDBS) or a double (dDBS) blood drop were performed as well.
  
  
  RESULTS
  Both assays could clearly distinguish the affected patients from the other subjects analyzed. Storage of DBS at 4 degrees C and below allowed a longer preservation of the enzymatic activities. No significant differences were detected between sDBS and dDBS.
  
  
  CONCLUSIONS
  DBS can be used for non-invasive, easy, inexpensive lysosomal enzyme assays. Reliability of assays on DBS needs to be checked using a control enzyme such as beta-galactosidase. DBS can be still reliably analyzed even if generated incidentally by two overlapped drops.
authors.affiliation: Centre for Rare Diseases and Department of Pediatrics, University of Padova, Italy.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Gasparotto
authors.forename: Rosella
authors.initials: R
authors.lastname: Tomanin
authors.forename: Anna Chiara
authors.initials: AC
authors.lastname: Frigo
authors.forename: Gabriela
authors.initials: G
authors.lastname: Niizawa
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Pasquini
authors.forename: Mariana
authors.initials: M
authors.lastname: Blanco
authors.forename: Maria Alice
authors.initials: MA
authors.lastname: Donati
authors.forename: Joan
authors.initials: J
authors.lastname: Keutzer
authors.forename: Franco
authors.initials: F
authors.lastname: Zacchello
authors.forename: Maurizio
authors.initials: M
authors.lastname: Scarpa
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000379:methods*; D006801:Humans; D007231:Infant, Newborn; D016464:Lysosomal Storage Diseases / Q000175:diagnosis*; D008875:Middle Aged; D000520:alpha-Glucosidases / Q000097:blood*; D001616:beta-Galactosidase / Q000097:blood*
chemical_list: D000520:alpha-Glucosidases; D001616:beta-Galactosidase