Twelve different enzyme assays on dried-blood filter paper samples for detection of patients with selected inherited lysosomal storage diseases.
BACKGROUND
Diagnoses of inherited lysosomal storage diseases are based on specific enzymatic assays performed on plasma, leukocytes, fibroblasts, and lately, dried-blood filter paper samples. We evaluated feasibility of detecting of patients with several inherited lysosomal storage diseases using dried-blood filter paper samples for appropriate enzyme assays.


METHODS
Fluorometric methods were used to evaluate the activities of arylsulfatase B, alpha-N-acetylglucosaminidase, chitotriosidase, alpha and beta-galactosidases, beta-glucosidase, beta-glucuronidase, total hexosaminidases, hexosaminidase A, alpha-iduronidase, and iduronate-2-sulfatase. A radiometric method was used for sphyngomyelinase determination. Single 3.0-mm diameter disks containing dried-blood samples were incubated at 37 degrees C with appropriate dilution buffers and artificial substrates, and the fluorescence or radioactivity was measured.


RESULTS
Our results showed a statistically significant difference of the enzyme activity between affected individuals and controls, in all the assays performed. In contrast, we have not obtained a complete differentiation between heterozygotes and controls with these assays.


CONCLUSIONS
Enzyme assay on dried-blood filter paper is a suitable method to screen for several lysosomal storage diseases. Despite the low individual incidence of these pathologies, the incorporation of individual enzyme assays in neonatal screening programs could be justified to screen for diseases with relatively high local frequency and therapeutic measures available.
Civallero
Gabriel
G
Medical Genetics Service, Hospital de Clinicas de Porto Alegre, RS, Brazil. gecivallero@yahoo.com
Michelin
Kristiane
K
de Mari
Jurema
J
Viapiana
Marli
M
Burin
Maira
M
Coelho
Janice C
JC
Giugliani
Roberto
R
D005470:Fluorometry; D006801:Humans; D016464:Lysosomal Storage Diseases / Q000175:diagnosis* / Q000201:enzymology; D008247:Lysosomes / Q000201:enzymology; D010209:Paper; D012680:Sensitivity and Specificity