MCOLN1 (mucolipin subfamily, member 1), also known as mucolipin-1 or TRPML1 (transient receptor potential cation channel, mucolipin subfamily, member 1), is the best-characterized member of the TRPML family since the mutations of this protein were associated with mucolipidosis type IV (MLIV), a devastating neurodegenerative disease [8, 9]. The gene discussed is MCOLN1; the disease is mucolipidosis type IV.