Danon disease is an X-linked dominant lysosomal and glycogen storage disorder caused by a mutation in a gene called LAMP2 (Lysosomal-Associated Membrane Protein 2), which encodes a protein that is an essential component of the lysosomial membrane and seems to have a role in the autofagosome-lysosome fusion [45]. The gene discussed is LAMP2; the disease is Danon disease.