[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Lysosomal storage diseases [Biochemistry](https://durgical.com/en/biochemistry/) · Topic # Lysosomal storage diseases When a lysosomal enzyme is missing, the molecule it should break down stays inside, the lysosome swells and the cell eventually fails. Updated 2026-11-01 ## Key facts - More than 70 single-gene diseases; together about 1 in 5,000 live births. - Mechanism: loss of an acid hydrolase, its activator protein, mannose 6-phosphate tagging, or a carrier that exports products from the lysosome. - Groups: sphingolipidoses (Gaucher, Tay–Sachs, Niemann–Pick, Fabry, Krabbe, metachromatic leukodystrophy), mucopolysaccharidoses (Hurler, Hunter), glycogenosis II (Pompe), mucolipidoses (I-cell disease). - The organ hit depends on where the substrate turns over most: gangliosides in neurons, glucosylceramide in macrophages, GAGs in connective tissue. - Nearly all are autosomal recessive; Fabry and Hunter are X-linked. ## In detail - 1. Material reaches the lysosome by endocytosis, phagocytosis or autophagy and should leave as monomers (sugars, amino acids, fatty acids). - 2. If one enzyme fails, its intermediate substrate builds up and lysosomes grow until they distort the cell (Gaucher cells, foam cells). - 3. Storage disturbs autophagy, membrane traffic and calcium, and triggers inflammation; the cell dies or works poorly. - 4. Residual enzyme activity sets the severity: no activity, infantile form; some activity, juvenile or adult forms. - 5. Diagnosis: enzyme activity in leukocytes or dried blood spots, substrates in urine (GAGs, oligosaccharides) or blood, and genetic testing. - 6. Treatments: enzyme replacement (the recombinant enzyme enters through the mannose 6-phosphate or mannose receptor), substrate reduction, pharmacological chaperones, haematopoietic stem cell transplant, and gene therapy under study. - 7. Infused enzyme does not cross the blood–brain barrier well: replacement improves organs and bone but helps the brain little. **Also called** Lysosomal storage disorders ## Clinical notes - Clinical clues: hepatosplenomegaly, developmental regression, coarse facial features, dysostosis multiplex, cherry-red spot or corneal clouding. - Foam cells or Gaucher cells in bone marrow support the diagnosis, which is confirmed by enzyme and gene testing. - Families are offered genetic counselling, and prenatal diagnosis when the variant is known. ## Pathways - [Lysosomal ganglioside breakdown](https://durgical.com/en/biochemistry/pathways/lysosomal-ganglioside-breakdown/) ## Related conditions - [Gaucher disease](https://durgical.com/en/conditions/gaucher-disease/) - [Tay–Sachs disease](https://durgical.com/en/conditions/tay-sachs-disease/) - [Niemann–Pick disease](https://durgical.com/en/conditions/niemann-pick-disease/) - [Fabry disease](https://durgical.com/en/conditions/fabry-disease/) - [Krabbe disease (globoid cell leukodystrophy)](https://durgical.com/en/conditions/krabbe-disease/) - [Metachromatic leukodystrophy](https://durgical.com/en/conditions/metachromatic-leukodystrophy/) - [Hurler syndrome (mucopolysaccharidosis type I)](https://durgical.com/en/conditions/hurler-syndrome/) - [Hunter syndrome (mucopolysaccharidosis type II)](https://durgical.com/en/conditions/hunter-syndrome/) - [I-cell disease (mucolipidosis II)](https://durgical.com/en/conditions/i-cell-disease/) - [Pompe disease (glycogen storage disease type II)](https://durgical.com/en/conditions/pompe-disease/) - [Sandhoff disease](https://durgical.com/en/conditions/sandhoff-disease/) - [Sanfilippo syndrome (mucopolysaccharidosis type III)](https://durgical.com/en/conditions/sanfilippo-syndrome/) - [Morquio syndrome (mucopolysaccharidosis type IV)](https://durgical.com/en/conditions/morquio-syndrome/) ## Related - [Sphingolipids and sphingolipidoses](https://durgical.com/en/biochemistry/topics/sphingolipids-and-sphingolipidoses/) - [Glycosaminoglycans (mucopolysaccharides)](https://durgical.com/en/biochemistry/topics/glycosaminoglycans/) - [Mannose 6-phosphate tagging (sending enzymes to the lysosome)](https://durgical.com/en/biochemistry/topics/mannose-6-phosphate-tagging/) - [Cell organelles and their metabolism](https://durgical.com/en/biochemistry/topics/cell-organelles-and-their-metabolism/) - [Glucocerebrosidase (acid β-glucosidase)](https://durgical.com/en/biochemistry/enzymes/glucocerebrosidase/) - [Hexosaminidase A (β-hexosaminidase A)](https://durgical.com/en/biochemistry/enzymes/hexosaminidase-a/) - [α-Galactosidase A](https://durgical.com/en/biochemistry/enzymes/galactosidase-a/) - [Acid sphingomyelinase](https://durgical.com/en/biochemistry/enzymes/acid-sphingomyelinase/) - [α-L-Iduronidase](https://durgical.com/en/biochemistry/enzymes/l-iduronidase/) ## Test yourself Think of the answer, then tap the question to see it. ## Why does enzyme replacement not improve brain damage in most lysosomal diseases? The recombinant enzyme is a large protein that does not cross the blood–brain barrier. ## Which classic lysosomal diseases are X-linked? Fabry and Hunter (MPS II); the others are autosomal recessive. ## What decides whether a lysosomal disease is infantile or adult-onset? Residual enzyme activity: less activity means earlier and more severe disease. ## How does replacement enzyme reach the cell's lysosomes? By endocytosis through mannose 6-phosphate or mannose receptors on the cell surface. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/biochemistry/topics/lysosomal-storage-diseases/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Lysosome Vesicle Biogenesis](https://reactome.org/PathwayBrowser/#/R-HSA-432720) (Reactome, 2026); [Glycosphingolipid metabolism](https://reactome.org/PathwayBrowser/#/R-HSA-1660662) (Reactome, 2026); [Glycosaminoglycan metabolism](https://reactome.org/PathwayBrowser/#/R-HSA-1630316) (Reactome, 2026); [Gaucher disease: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/gaucher-disease/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011). [← All of biochemistry](https://durgical.com/en/biochemistry/) ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/biochemistry/topics/lysosomal-storage-diseases/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/topics/lysosomal-storage-diseases/