Rapid diagnostic testing procedures for lysosomal storage disorders: alpha-glucosidase and beta-galactosidase assays on dried blood spots.
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.
Gasparotto
Nicoletta
N
Centre for Rare Diseases and Department of Pediatrics, University of Padova, Italy.
Tomanin
Rosella
R
Frigo
Anna Chiara
AC
Niizawa
Gabriela
G
Pasquini
Elisabetta
E
Blanco
Mariana
M
Donati
Maria Alice
MA
Keutzer
Joan
J
Zacchello
Franco
F
Scarpa
Maurizio
M
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*
D000520:alpha-Glucosidases; D001616:beta-Galactosidase