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MAN2B1 gene

mannosidase alpha class 2B member 1

Normal Function

The MAN2B1 gene provides instructions for making the enzyme alpha-mannosidase. This enzyme works in the lysosomes, which are compartments that digest and recycle materials in the cell. Within lysosomes, the enzyme helps break down complexes of sugar molecules (oligosaccharides) attached to certain proteins (glycoproteins). In particular, alpha-mannosidase helps break down oligosaccharides containing a sugar molecule called mannose.

Health Conditions Related to Genetic Changes


More than 120 mutations in the MAN2B1 gene have been identified in people with alpha-mannosidosis, a rare inherited disorder that causes problems in many organs and tissues of the body. Affected individuals may have intellectual disability, distinctive facial features, and skeletal abnormalities. Some of the MAN2B1 gene mutations that cause alpha-mannosidosis change one protein building block (amino acid) in the alpha-mannosidase enzyme. Other mutations result in an abnormally shortened enzyme, or cause the enzyme to be pieced together incorrectly.

These mutations interfere with the ability of the alpha-mannosidase enzyme to perform its role in breaking down mannose-containing oligosaccharides. These oligosaccharides accumulate in the lysosomes and cause the cells to malfunction and eventually die. Tissues and organs are damaged by the abnormal accumulation of oligosaccharides and the resulting cell death, leading to the characteristic features of alpha-mannosidosis.

More About This Health Condition

Other Names for This Gene

  • lysosomal acid alpha-mannosidase
  • MANB
  • mannosidase, alpha B, lysosomal
  • mannosidase, alpha, class 2B, member 1

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Essentials of Glycobiology (second edition, 2009): Glycoprotein Degradation
  • Hansen G, Berg T, Riise Stensland HM, Heikinheimo P, Klenow H, Evjen G, Nilssen O, Tollersrud OK. Intracellular transport of human lysosomal alpha-mannosidase and alpha-mannosidosis-related mutants. Biochem J. 2004 Jul 15;381(Pt 2):537-46. doi: 10.1042/BJ20031499. Citation on PubMed or Free article on PubMed Central
  • Kuokkanen E, Riise Stensland HM, Smith W, Kjeldsen Buvang E, Van Nguyen L, Nilssen O, Heikinheimo P. Molecular and cellular characterization of novel alpha-mannosidosis mutations. Hum Mol Genet. 2011 Jul 1;20(13):2651-61. doi: 10.1093/hmg/ddr167. Epub 2011 Apr 19. Citation on PubMed
  • Malm D, Nilssen O. Alpha-mannosidosis. Orphanet J Rare Dis. 2008 Jul 23;3:21. doi: 10.1186/1750-1172-3-21. Citation on PubMed or Free article on PubMed Central
  • Pittis MG, Montalvo AL, Heikinheimo P, Sbaragli M, Balducci C, Persichetti E, Van Maldergem L, Filocamo M, Bembi B, Beccari T. Funtional characterization of four novel MAN2B1 mutations causing juvenile onset alpha-mannosidosis. Clin Chim Acta. 2007 Jan;375(1-2):136-9. doi: 10.1016/j.cca.2006.06.034. Epub 2006 Jul 6. Citation on PubMed
  • Sbaragli M, Bibi L, Pittis MG, Balducci C, Heikinheimo P, Ricci R, Antuzzi D, Parini R, Spaccini L, Bembi B, Beccari T. Identification and characterization of five novel MAN2B1 mutations in Italian patients with alpha-mannosidosis. Hum Mutat. 2005 Mar;25(3):320. doi: 10.1002/humu.9310. Citation on PubMed
  • Sun H, Wolfe JH. Recent progress in lysosomal alpha-mannosidase and its deficiency. Exp Mol Med. 2001 Mar 31;33(1):1-7. doi: 10.1038/emm.2001.1. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.