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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed March 2012

What is the official name of the MBL2 gene?

The official name of this gene is “mannose-binding lectin (protein C) 2, soluble.”

MBL2 is the gene's official symbol. The MBL2 gene is also known by other names, listed below.

What is the normal function of the MBL2 gene?

The MBL2 gene provides instructions for making a protein that assembles into a protein complex called mannose-binding lectin. Functional mannose-binding lectins are made up of two to six protein groups called trimers, which are each composed of three of the protein pieces (subunits) produced from the MBL2 gene. This protein complex plays an important role in the immune system's response to foreign invaders (pathogens).

Mannose-binding lectin recognizes and attaches (binds) to sugars, such as mannose, fucose, and glucose, that are found on the surface of bacteria, viruses, and yeast. This binding turns on (activates) the complement system, which is a group of immune system proteins that work together to destroy pathogens, trigger inflammation, and remove debris from cells and tissues. Attachment of mannose-binding lectin also targets the pathogen to be engulfed and broken down by special immune cells. Recognition of foreign invaders by mannose-binding lectin provides one of the body's first lines of defense against infection.

Does the MBL2 gene share characteristics with other genes?

The MBL2 gene belongs to a family of genes called COLEC (collectins).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? ( in the Handbook.

How are changes in the MBL2 gene related to health conditions?

mannose-binding lectin deficiency - increased risk from variations of the MBL2 gene

Several common mutations of the MBL2 gene can lead to a condition called mannose-binding lectin deficiency. People with this condition have low levels of mannose-binding lectin and may be susceptible to recurrent infections. Several of the disease-associated mutations occur in a region of the MBL2 gene known as exon 1 and result in a change to single protein building blocks (amino acids) in the mannose-binding lectin subunit. Other mutations occur in an area of DNA near the MBL2 gene called the promoter region, which helps control the production of the mannose-binding lectin subunit.

The change of a single amino acid in the mannose-binding lectin subunit eliminates its ability to assemble into the functional mannose-binding lectin. Similarly, certain mutations in the promoter region of the MBL2 gene reduce production of the mannose-binding lectin subunit, leading to a decreased number of subunits available for protein assembly and a reduction in the amount of functional protein. With decreased levels of mannose-binding lectin, the body does not recognize and fight foreign invaders efficiently. Consequently, infections can be more common in people with this condition. However, researchers believe that a number of factors, including other genetic and environmental factors, are involved in the development of mannose-binding lectin deficiency.

Where is the MBL2 gene located?

Cytogenetic Location: 10q11.2

Molecular Location on chromosome 10: base pairs 52,765,379 to 52,772,840

The MBL2 gene is located on the long (q) arm of chromosome 10 at position 11.2.

The MBL2 gene is located on the long (q) arm of chromosome 10 at position 11.2.

More precisely, the MBL2 gene is located from base pair 52,765,379 to base pair 52,772,840 on chromosome 10.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about MBL2?

You and your healthcare professional may find the following resources about MBL2 helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the MBL2 gene or gene products?

  • COLEC1
  • collectin-1
  • mannan-binding lectin
  • mannose-binding lectin 2, soluble (opsonic defect)
  • mannose-binding lectin (protein C) 2, soluble (opsonic defect)
  • mannose-binding protein C
  • mannose-binding protein C precursor
  • MBL
  • MBL2D
  • MBP
  • MBP1
  • MBP-C

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding MBL2?

acids ; amino acid ; bacteria ; deficiency ; DNA ; exon ; fucose ; gene ; glucose ; immune system ; infection ; inflammation ; mannose ; pathogen ; precursor ; promoter ; promoter region ; protein ; soluble ; subunit

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (


  • Arora M, Munoz E, Tenner AJ. Identification of a site on mannan-binding lectin critical for enhancement of phagocytosis. J Biol Chem. 2001 Nov 16;276(46):43087-94. Epub 2001 Aug 30. (
  • Bouwman LH, Roep BO, Roos A. Mannose-binding lectin: clinical implications for infection, transplantation, and autoimmunity. Hum Immunol. 2006 Apr-May;67(4-5):247-56. Epub 2006 Apr 17. Review. (
  • Martin P, Lerner A, Johnson L, Lerner DL, Haraguchi S, Good RA, Day NK. Inherited mannose-binding lectin deficiency as evidenced by genetic and immunologic analyses: association with severe recurrent infections. Ann Allergy Asthma Immunol. 2003 Oct;91(4):386-92. (
  • NCBI Gene (
  • Weis WI, Drickamer K, Hendrickson WA. Structure of a C-type mannose-binding protein complexed with an oligosaccharide. Nature. 1992 Nov 12;360(6400):127-34. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: March 2012
Published: March 23, 2015