Definition:

Lysosomal storage diseases (LSDs) are a group of inherited diseases that are characterised by the intracellular accumulation of incompletely degraded macromolecules. They result from a genetic defect in cellular transport or metabolism of molecules within the lysosome. Most of the patients with a LSD are born apparently healthy and the symptoms develop progressively. Treatment is directed toward symptomatic care of secondary complications for most of these diseases. For some individuals, hematopoietic stem cell transplantation or enzyme-replacement therapy can be effective. LSDs are divided into the following 5 groups. For details, please refer to the each entry. 1. Defects in glycan degradation: Fabry disease, Mucopolysaccharidosis, Glycoproteinoses, Defects in the degradation of sulfatide, Defects in the degradation of ganglioside, Pompe disease, Prosaposin deficiency 2. Defects in lipid degradation: Defects in the degradation of sphingomyelin, Wolman disease 3. Defects in protein degradation: Neuronal ceroid lipofuscinosis, Lysosomal cysteine protease deficiencies, Acid phosphatase deficiency 4. Defects in lysosomal transporters: Cystinosis, Sialuria, Danon disease 5. Defects in lysosomal trafficking: Niemann-Pick disease type C, Mucolipidosis II, III, and IV, Neuronal ceroid lipofuscinosis, Hermansky-Pudlak syndrome, Chediak-Higashi syndrome