The guidelines, European or American, outline that a genetic diagnosis is merely for a more accurate diagnosis of family members, having less implications for disease management, with some exceptions, e.g., Anderson-Fabry disease for substitution therapy or liver transplantation in transthyretin-related amyloidosis or follow-up for conduction defects and indication for pacemaker in desmin (DES) and AMP-activated protein kinase (PRKAG2) mutated subjects. The gene discussed is TTR; the disease is Fabry disease.