A group of inherited/genetic diseases characterized by lysosomal dysfunction which result in accumulation of lipids and/or polysaccharides within the cell. These diseases, in most cases, result from mutations in enzymes involved in lysosomal pathways. In MLIV, the disease results from a mutation in a transmembrane protein that transports ions (MCOLN1). The primary effect of this mutation may be a disruption of new lysosome formation.
