Given the fact that in the setting of low global native myocardial T1, the sole differential to cardiac iron overload is Anderson-Fabry disease (glycosphingolipid storage disease due to alpha-galactosidase A deficiency) and that the overlap between these entities is unlikely, native myocardial T1-mapping emerges as an important tool for myocardial iron overload detection. The gene discussed is GLA; the disease is hyperinsulinemic hypoglycemia, familial, 4.