Fabry disease: Diagnosis by α-galactosidase activities in tears
- 18 August 1975
- journal article
- Published by Elsevier BV in Clinica Chimica Acta; International Journal of Clinical Chemistry
- Vol. 63 (1), 81-90
- https://doi.org/10.1016/0009-8981(75)90382-4
Abstract
The enzymatic diagnosis of hemizygotes with Fabry disease and heterozygous carriers was accomplished by the fluorometric determination of α-galactosidase activities in tears. Two components of total α-galactosidase activity were differentiated by their relative thermostabilities and by chromatography on DEAE-cellulose. The major component, α-galactosidase A, was thermolabile and represented approximately 90% of total activity; the remaining activity was thermostable, eluted at a slightly higher salt concentration and was designated α-galactosidase B. A single, symmetric pH optimum was observed for total α-galactosidase activities from heterozygotes and normal individuals, whereas the total activity from hemizygotes, which was about 10% of that in normal controls, had a broad pH profile, identical to those for α-galactosidase B activities from all individuals studied. The apparent Km values for total activities were 3.2, 4.0, and greater than 13 mM for normal individuals, heterozygotes, and hemizygotes, respectively. In contrast, apparent Km values for α-galactosidase B activities were greater than 13 mM for all individuals, further suggesting that the residual activity in hemizygotes with Fabry disease represented the α-galactosidase B component. Of the potential inhibitors studied, α-d-melibiose was found to competitively inhibit total α-galactosidase activity (Ki ~ 10 mM). These studies demonstrate that tears provide an easily obtainable source of freshly secreted enzyme for the diagnosis of hemizygotes and heterozygotes with Fabry disease and suggest that tears may be useful for the diagnosis of other inborn errors of metabolism.Keywords
This publication has 15 references indexed in Scilit:
- Human Kidney α-GalactosidaseThe Journal of Biochemistry, 1974
- Hydrolysis of ceramide trihexoside by a specific α-galactosidase from human liverBiochemical Journal, 1973
- Characterization of a Blood Group B Glycolipid, Accumulating in the Pancreas of a Patient with Fabry's DiseasePublished by Elsevier BV ,1973
- Pleistocene Man in Australia: Age and Significance of the Mungo SkeletonNature, 1972
- Detection and properties of an acid α-galactosidase (ceramidetrihexosidase) in normal human urineBiochimica et Biophysica Acta (BBA) - General Subjects, 1972
- Substrate specificity of ceramide trihexosidaseFEBS Letters, 1972
- Fabry's Disease: Differentiation between Two Forms of α-Galactosidase by MyoinositolScience, 1972
- Fabry's Disease: Alpha-Galactosidase DeficiencyScience, 1970
- Enzymatic Defect in Fabry's DiseaseNew England Journal of Medicine, 1967
- Fabry's Disease: Classification as a Sphingolipidosis and Partial Characterization of a Novel GlycolipidJournal of Biological Chemistry, 1963