MCOLN1 and mucolipidosis type IV: Mucolipidosis, Type IV (MLIV) is caused by mutations in MCOLN1 (Mucolipin 1), an endo-lysosomal pH sensitive channel that facilitates diffusion of monovalent and divalent ions (Dong et al., 2008) and facilitates lysosomal and autophagic regulation via its interaction with TFEB and mTOR signaling (Zhang et al., 2016).