Sly Syndrome, Sucrase-Isomaltase Deficiency, Valproic Acid Metabolism Pathway, Tay-Sachs Disease, Sialuria or French Type Sialuria, Amino Sugar Metabolism, Salla Disease/Infantile Sialic Acid Storage Disease, G(M2)-Gangliosidosis: Variant B, Tay-Sachs Disease, Porphyria Variegata (PV), Congenital Erythropoietic Porphyria (CEP) or Gunther Disease, Acute Intermittent Porphyria, Hereditary Coproporphyria (HCP), and Porphyrin Metabolism (Figure 5C). The gene discussed is SI; the disease is acquired polycythemia vera.