Effect of sample collection on alpha-galactosidase A enzyme activity measurements in dried blood spots on filter paper.
BACKGROUND
Fabry disease is an X-linked lysosomal storage disorder due to deficiency of alpha galactosidase A (AGAL, EC 3.2.1.22). Despite increasing utilization of dried blood spot (DBS) as samples for AGAL enzyme assays, the effects of blood sample collection techniques on enzyme activity have not been studied.


METHODS
DBS samples were prepared by spotting blood collected into an ethylenediaminetetraacetic acid (EDTA) tube and by direct application of blood from a finger prick or a venipuncture syringe. AGAL activity was measured quantitatively by detecting the fluorescence of 4-methylumbelliferone (4-MU) generated using the substrate 4-methylumbelliferyl-alpha-D-glucopyranoside (4-MUGal) in an acidic pH for 20 h. N-acetyl-D-galactosamine (GalNAc) was used to inhibit alpha-galactosidase B (EC 3.2.1.49).


RESULTS
We studied 88 previously diagnosed Fabry disease patients and 690 healthy controls. Average AGAL activity in DBS samples prepared using EDTA tubes was higher compared to those spotted directly irrespective of disease status.


CONCLUSIONS
The study confirms the need for collection method-specific reference ranges using DBS samples.
Olivova
Petra
P
Genzyme, Framingham, MA, United States.
van der Veen
Kristen
K
Cullen
Emmaline
E
Rose
Michael
M
Zhang
X Kate
XK
Sims
Katherine B
KB
Keutzer
Joan
J
Browning
Marsha F
MF
D000328:Adult; D001774:Blood Chemical Analysis / Q000379:methods*; D016022:Case-Control Studies; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology; D000795:Fabry Disease / Q000097:blood / Q000201:enzymology; D005260:Female; D005374:Filtration; D006801:Humans; D008297:Male; D010209:Paper; D015203:Reproducibility of Results; D013048:Specimen Handling / Q000379:methods*; D000519:alpha-Galactosidase / Q000097:blood* / Q000378:metabolism*
D004492:Edetic Acid; D000519:alpha-Galactosidase