RESUMO
Fabry disease is a rare lysosomal storage disorder caused by mutations in the GLA gene, resulting in reduced or absent α-Gal A activity. Migalastat is an oral chaperone therapy for Fabry patients with amenable GLA variants. We previously reported a case of a 60-year-old male patient with a classic phenotype of Fabry disease, presenting with two GLA variants: p.R356Q and p.G360R. Herein, we report that, although these two missense variants are individually classified as amenable to migalastat in the validated in vitro human embryonic kidney-293 cell-based assay, their combination precludes the patient to be treated with this oral chaperone. This case illustrates how therapeutic decisions may be challenging and how a good genotypic characterization of Fabry patients is critical for the selection of the correct therapeutic strategy.
Fabry disease is a rare genetic disease that is part of a group of conditions called lysosomal storage diseases. It is characterized by an abnormal accumulation of glycosphingolipids, a subclass of glycolipids which are important components of the body's cell membranes. This accumulation is caused by a reduction in, or absence of, enzyme α-Gal A activity, which normally breaks glycosphingolipids down into smaller units, avoiding their accumulation. The absence or reduction in the α-Gal A enzyme activity is caused by mutations (changes in the normal DNA sequence) in the GLA gene. Migalastat is an oral treatment for Fabry patients with GLA mutations that respond to this treatment. We report a case of a 60-year-old male patient with Fabry disease, presenting with two GLA mutations (p.R356Q and p.G360R). Although these mutations are individually amenable to migalastat, their combination and interaction in the same chromosome precludes response to this treatment. This case illustrates how therapeutic decisions for treating Fabry disease can be challenging depending on the mutations causing the disease and how genetic material is decisive for therapy selection.