Whole-blood alpha-D-galactosidase A activity for the identification of Fabry's patients

Objectives: ERT application to Fabry's disease patients needs sensitive assay method of the missing enzyme (α-d-galactosidase A) to achieve early diagnosis. Design and methods: A new fluorimetric assay method of alpha;-d-galactosidase A was developed, using whole blood (WB) from 30 healthy individuals, 7 hemizygous males and 7 heterozygous females with Fabry's disease. This method was compared with the traditional dried blood spot (DBS) method. Results: WB method analytical characteristics are: linearity up to 2000. mU/L; detection limit: 4. mU/L; linearity versus time: 6. h; enzyme stability: 7. days at 4 °C; total analytical imprecision: from 3.27% to 5.72%. Sensitivity was higher in WB than DBS method. All hemizygous Fabry's patients were identified by both the WB and DBS methods. With regards to the seven heterozygous carriers five could be identified by the WB methods and three by the DBS method. Conclusion: The WB assay method for α-d-galactosidase A appears to be reliable and proposable as a routine method for prompt diagnosis of Fabry disease in selected at-risk populations.