A pharmacogenetic approach to identify mutant forms of α‐galactosidase a that respond to a pharmacological chaperone for Fabry disease

Fabry disease is caused by mutations in the gene ( GLA) that encodes α‐galactosidase A (α‐Gal A). The iminosugar AT1001 (GR181413A, migalastat hydrochloride, 1‐deoxygalactonojirimycin) is a pharmacological chaperone that selectively binds and stabilizes α‐Gal A, increasing total cellular levels and activity for some mutant forms (defined as “responsive”). In this study, we developed a cell‐based assay in cultured HEK‐293 cells to identify mutant forms of α‐Gal A that are responsive to AT1001. Concentration‐dependent increases in α‐Gal A activity in response to AT1001 were shown for 49 (60%) of 81 mutant forms. The responses of α‐Gal A mutant forms were generally consistent with the responses observed in male Fabry patient‐derived lymphoblasts. Importantly, the HEK‐293 cell responses of 19 α‐Gal A mutant forms to a clinically achievable concentration of AT1001 (10 µM) were generally consistent with observed increases in α‐Gal A activity in peripheral blood mononuclear cells from male Fabry patients orally administered AT1001 during Phase 2 clinical studies. This indicates that the cell‐based responses can identify mutant forms of α‐Gal A that are likely to respond to AT1001 in vivo. Thus, the HEK‐293 cell‐based assay may be a useful aid in the identification of Fabry patients with AT1001‐responsive mutant forms. Hum Mutat 32:1–13, 2011. © 2011 Wiley‐Liss, Inc.