Two-tier approach for the detection of alpha-galactosidase A deficiency in kidney transplant recipients.

Background: Anderson-Fabry disease (AFD) is an X-linked condition originating from a deficiency in alpha-galactosidase, a lysosomal enzyme. Multi-organ involvement ensues in early adulthood and vital organs are affected: the kidneys, brain, heart. Several reports however suggest that AFD is underdiagnosed.
Methods: We screened a kidney transplant population using a two-tier approach. The first tier was the determination of alpha-galactosidase A (AGALA) activity using a dried blood spot on filter paper (DBFP); in the second tier, patients with the lowest alpha-galactosidase levels were further subjected to mutation analysis of the GLA gene.
Results: From the database of 2328 patients, 1233 subjects met the inclusion criteria. Finally, after informed consent, 673 patients were screened (54.5%-395 women and 278 men). DBFP analysis resulted in a mean AGALA of 2.63 +/- 2.48 micromol/L/h (2.5 and 97.5 percentile were 0.0001 and 5.07 micromol/L/h, respectively). Eleven patients were subjected to further genetic analysis. In a male patient a pathogenic missense mutation p.Ala143Thr (c.427A>G) was identified.
Conclusions: Our results show that the proposed approach can detect AFD patients in a until now seldomly screened high-risk group: kidney transplant patients. We conclude that screening for AFD in high-risk populations is a cost-effective, technically feasible and clinically valuable objective.