Investigating Fabry disease - some lessons learned

Despite recent advances, there is still much to be learned about the pathogenesis of Fabry disease. The categorization of GLA gene missense mutations has been complicated by the fact that some missense variants may fall into more than one category. For instance, the A143T variant may cause late-onset Fabry disease in some subjects and not result in Fabry disease in others (pseudo-deficient). Efforts to mitigate the pathobiology of α-galactosidase A deficiency should differentiate between damaging (maladaptive) consequences and compensatory (adaptive) changes. Current therapy leaves a significant unmet need, especially concerning cardiovascular complications and cardiological clinical outcomes. Non-Fabry-specific therapy is necessary and quite beneficial and must be utilized. Its contribution should be considered when trying to assess the net effect of Fabry-specific therapy. Enzyme replacement therapy (ERT) can be administered to patients independently of their GLA genotype, as it slows the decline of kidney function in most patients if initiated sufficiently early in the disease course. Migalastat has better tissue penetration than ERT, but its usefulness is restricted to patients with amenable missense GLA variants. However, it is important to realize that in a substantial proportion of common amenable mutations, migalastat increases α-galactosidase A activity level beyond the disease threshold and thus eliminates the metabolic disturbance that is at the center of Fabry disease. Substrate reduction therapy and gene therapy approaches are being developed, but these therapeutic modalities have their own limitations and difficulties.