G RAMAN1, J WONG1, A MALLAWAARACHCHI1, C LOPEZ1, K ESPINOZA1, A MAKRIS1
1Sydney South West Area Health Service, New South Wales, Australia
Aim: Establish the prevalence of Fabry Disease in chronic stable dialysis patients in South West Sydney Local Health District (SWSLHD) and to compare two diagnostic laboratories (Lab A and Lab B) for Fabry disease.
Background: Fabry disease is a rare genetic lysosomal storage disease due to complete or partial alpha-galactosidase A (A-GAL A) deficiency resulting in accumulation of globotrisylceramide (GB3) and end organ dysfunction including renal failure. Diagnosis is based on assessing enzyme activity (Labs A and B) or in combination with genetic testing via massively parallel sequencing of the GLA gene (Lab B).
Methods: A 6 month observational cross-sectional study of prevalent SWSLHD dialysis patients was commenced in February 2017. Dried blood spots (DBS) were collected and dispatched to Labs A &B as per manufacturer’s instructions.
Results: To date 102 haemodialysis patients were approached, 27 were unable to consent and 5 declined to participate. 70 patients (20 female and 50 male) were tested thus far. Lab A identified 16 (2 male, 14 female) patients with low A-GAL-A activity however 6 of these also reported low control enzyme activity. Lab B also reported low A-GAL-A activity in 24 males. All females and males with low enzyme activity underwent genetic testing and were found to be negative.
Conclusions: Low a-GAL-A activity by DBS is common in haemodialysis patients, resulting in false positives mandating a genetic test to confirm the diagnosis of Fabry disease in this population. Lab B provides a more definitive answer.