MCOLN2 and retinal degeneration: MLIV is characterized by psychomotor abnormalities, corneal clouding, retinal degeneration, and achlorhydria, which results in an increase in blood gastrin levels, iron deficiency due to an absence of acid secretion in the stomach, and endolysosomal accumulation of macromolecules, lipids, and heavy metals like zinc and iron in endolysosomes throughout the body.1063., 1064., 1065., 1066., 1067., 1068. In human TRPML2, an SNP, which is common in certain African populations, results in the TRPML2 variant TRPML2K370Q.