It is highly recommended performing molecular testing in every patient with low a-GAL enzymatic activity (i) to identify the specific mutation of the GLA gene 64,65 and (ii) to rule out non-pathogenic mutations (polymorphisms), such as the D313Y, that may cause enzymatic pseudo-deficiency and, consequently, lead to misdiagnosis of Fabry disease 65,66. The gene discussed is GLA; the disease is Fabry disease.