E F Wallin1, M R Clatworthy, N R Pritchard. 1. Division of Renal Medicine, University of Cambridge Department of Medicine, and Addenbrooke's Hospital, Cambridge, UK. lizwallin@doctors.org.uk
Abstract
BACKGROUND: Fabry disease is an X-linked lysosomal storage disorder in which deficiency of α-Galactosidase A (α-Gal A), leads to accumulation of glycosphingolipids in the vascular endothelium, kidneys and heart. Males with classical disease present in childhood, however some individuals with low levels of α-Gal A activity present atypically with adult onset renal impairment. Screening studies in patients with established end-stage renal failure (ESRF) suggest that up to 1.5% of patients have sub-normal α-Gal A levels. We used the dried blood spot (DBS) enzyme activity test to screen for undiagnosed Fabry disease in patients with ESRF. METHODS: Male hemodialysis patients treated at a single UK center (n = 155) were screened using the DBS assay. In patients with low enzyme activity on DBS, α-Gal A activity was assessed in plasma and leucocytes. RESULTS: 8 of the 155 (5%) patients screened showed low enzyme activity on the DBS assay. Confirmatory testing of plasma and leucocyte α-Gal A activity showed normal activity in all cases tested, indicating a false positive DBS result. CONCLUSIONS: This study is the first screening program in UK hemodialysis patients using the DBS test and did not identify any new cases of Fabry disease. In this cohort, the DBS enzyme assay had a false positive rate of 2.6%, emphasizing the need for validation with alternative techniques.
BACKGROUND:Fabry disease is an X-linked lysosomal storage disorder in which deficiency of α-Galactosidase A (α-Gal A), leads to accumulation of glycosphingolipids in the vascular endothelium, kidneys and heart. Males with classical disease present in childhood, however some individuals with low levels of α-Gal A activity present atypically with adult onset renal impairment. Screening studies in patients with established end-stage renal failure (ESRF) suggest that up to 1.5% of patients have sub-normal α-Gal A levels. We used the dried blood spot (DBS) enzyme activity test to screen for undiagnosed Fabry disease in patients with ESRF. METHODS: Male hemodialysis patients treated at a single UK center (n = 155) were screened using the DBS assay. In patients with low enzyme activity on DBS, α-Gal A activity was assessed in plasma and leucocytes. RESULTS: 8 of the 155 (5%) patients screened showed low enzyme activity on the DBS assay. Confirmatory testing of plasma and leucocyte α-Gal A activity showed normal activity in all cases tested, indicating a false positive DBS result. CONCLUSIONS: This study is the first screening program in UK hemodialysis patients using the DBS test and did not identify any new cases of Fabry disease. In this cohort, the DBS enzyme assay had a false positive rate of 2.6%, emphasizing the need for validation with alternative techniques.
Authors: L van der Tol; David Cassiman; Gunnar Houge; Mirian C Janssen; Robin H Lachmann; Gabor E Linthorst; Uma Ramaswami; Claudia Sommer; Camilla Tøndel; Michael L West; Frank Weidemann; Frits A Wijburg; Einar Svarstad; Carla Em Hollak; Marieke Biegstraaten Journal: JIMD Rep Date: 2014-09-16