Direct comparison of enzyme measurements from dried blood and leukocytes from male and female Fabry disease patients
Anderson–Fabry disease is an X-linked disorder that is caused by deficiency of the lysosomal enzyme α-galactosidase A. Symptoms include chronic progressive painful small-fibre neuropathy, cornea verticillata, renal failure and heart disease. Interestingly, female heterozygous patients may also show severe symptoms. After clinical suspicion, usually the determination of α-galactosidase activity in leukocytes is requested first. Alternatively, an enzymatic assay using dried blood specimens has been described. Dried blood samples require less material and are substantially more stable (several months at room temperature) than whole-blood specimens. To validate the new method and to asses its usefulness for diagnosis of female patients, enzyme activities of α-galactosidase, β-galactosidase and β-glucuronidase from 78 known Fabry patients were compared (29 males, 47 females) between both materials. In summary, the determination of α-galactosidase activity using dried blood and leukocytes as well as the ratio of α-galactosidase to β-glucuronidase in dried blood can improve the diagnostic specificity in cases of female patients who are difficult to identify when only leukocyte enzyme activities are considered.