Galactocerebrosidase assay on dried-leukocytes impregnated in filter paper for the detection of Krabbe disease.

[krabbe disease]

Krabbe disease (KD ) is an inherited lysosomal storage disease (LSD ) caused by the deficiency of galactocerebrosidase (GALC ) and is characterized by a severe and progressive leukodystrophy with death frequently before one year of life in the classical early -onset form . As a consequence of the enzyme defect , globoid cells containing undigested galactosylceramide are observed and are characteristic of the disease . Hematopoietic stem cell transplantation is the current treatment for this disease , with some success in the classical cases if performed very early in life . Definitive diagnosis of KD is generally accessed by determination of GALC in leukocytes or fibroblasts . For the last few years , dried-blood filter paper (DBFP ) samples have been increasingly used for lysosomal enzyme assays . Originally , some lysosomal enzymes could not be tested in DBFP samples using fluorometric assays , including GALC , heparan-sulfamidase and a few others . Recently , we reported successful results using dried-leukocytes filter paper (DLFP ) samples for heparan sulfamidase and β-galactosidase . Extending these studies , we present now a new GALC assay on these type of samples .Adapted leukocyte fluorometric assay was used for the evaluation of GALC in DLFP samples .O ur results using this method showed a clear discrimination between GALC levels observed in KD patients and healthy controls .The assay is robust and reliable and could be adopted by reference laboratories for diagnosis of LSDs . It is expected that the use of DLPF would make it possible to diagnose patients living in isolated areas , where liquid samples usually have to be transported over several days and sometimes across country borders before reaching reference laboratories .