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MASP1 gene

MBL associated serine protease 1

Normal Function

The MASP1 gene provides instructions for making proteins that are involved in a series of steps called the lectin complement pathway. This pathway is thought to help direct the movement (migration) of cells during development before birth to form the organs and systems of the body. It appears to be particularly important in directing the migration of neural crest cells. These cells give rise to various tissues including many tissues in the face and skull, the glands that produce hormones (endocrine glands), and portions of the nervous system. After birth, the lectin complement pathway is involved in the immune system.

Proteins called MASP-1, MASP-3, and MAp44 can be produced from the MASP1 gene, depending on how the gene's instructions are pieced together. These proteins differ at one end of their structure. The MASP-1 and MASP-3 proteins have different versions of regions called serine protease domains, while the MAp44 protein has no serine protease domain. Researchers are studying whether these proteins play different roles in the lectin complement pathway.

Health Conditions Related to Genetic Changes

3MC syndrome

At least 11 MASP1 gene mutations have been identified in people with 3MC syndrome, a disorder characterized by unusual facial features and a variety of problems affecting other tissues and organs of the body. Because all of the MASP1 gene mutations that cause 3MC syndrome affect the MASP-3 protein, alterations in this protein's function are thought to account for the signs and symptoms of 3MC syndrome. Because parts of the three protein versions are the same, some of the MASP1 gene mutations affect the other protein versions in addition to affecting MASP-3.

The protein changes result in faulty control of cell migration in early development, leading to the various abnormalities that occur in this disorder. Researchers suggest that similar pathways in the immune system can compensate for problems in the lectin complement pathway, which explains why immune system abnormalities are not part of 3MC syndrome.

More About This Health Condition

Other Names for This Gene

  • 3MC1
  • complement factor MASP-3
  • complement-activating component of Ra-reactive factor
  • CRARF1
  • mannan-binding lectin serine peptidase 1 (C4/C2 activating component of Ra-reactive factor)
  • mannose-binding lectin-associated serine protease 1
  • mannose-binding protein-associated serine protease
  • MAP1
  • MAp44
  • MASP
  • MASP3
  • PRSS5
  • Ra-reactive factor serine protease p100
  • RaRF
  • serine protease 5

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


  • Atik T, Koparir A, Bademci G, Foster J 2nd, Altunoglu U, Mutlu GY, Bowdin S, Elcioglu N, Tayfun GA, Atik SS, Ozen M, Ozkinay F, Alanay Y, Kayserili H, Thiel S, Tekin M. Novel MASP1 mutations are associated with an expanded phenotype in 3MC1 syndrome. Orphanet J Rare Dis. 2015 Sep 30;10:128. doi: 10.1186/s13023-015-0345-3. Citation on PubMed or Free article on PubMed Central
  • Degn SE, Jensen L, Gal P, Dobo J, Holmvad SH, Jensenius JC, Thiel S. Biological variations of MASP-3 and MAp44, two splice products of the MASP1 gene involved in regulation of the complement system. J Immunol Methods. 2010 Sep 30;361(1-2):37-50. doi: 10.1016/j.jim.2010.07.006. Epub 2010 Jul 29. Citation on PubMed
  • Henriksen ML, Brandt J, Andrieu JP, Nielsen C, Jensen PH, Holmskov U, Jorgensen TJ, Palarasah Y, Thielens NM, Hansen S. Heteromeric complexes of native collectin kidney 1 and collectin liver 1 are found in the circulation with MASPs and activate the complement system. J Immunol. 2013 Dec 15;191(12):6117-27. doi: 10.4049/jimmunol.1302121. Epub 2013 Oct 30. Citation on PubMed
  • Rooryck C, Diaz-Font A, Osborn DP, Chabchoub E, Hernandez-Hernandez V, Shamseldin H, Kenny J, Waters A, Jenkins D, Kaissi AA, Leal GF, Dallapiccola B, Carnevale F, Bitner-Glindzicz M, Lees M, Hennekam R, Stanier P, Burns AJ, Peeters H, Alkuraya FS, Beales PL. Mutations in lectin complement pathway genes COLEC11 and MASP1 cause 3MC syndrome. Nat Genet. 2011 Mar;43(3):197-203. doi: 10.1038/ng.757. Epub 2011 Jan 23. Citation on PubMed or Free article on PubMed Central
  • Sirmaci A, Walsh T, Akay H, Spiliopoulos M, Sakalar YB, Hasanefendioglu-Bayrak A, Duman D, Farooq A, King MC, Tekin M. MASP1 mutations in patients with facial, umbilical, coccygeal, and auditory findings of Carnevale, Malpuech, OSA, and Michels syndromes. Am J Hum Genet. 2010 Nov 12;87(5):679-86. doi: 10.1016/j.ajhg.2010.09.018. Epub 2010 Oct 28. Citation on PubMed or Free article on PubMed Central
  • Yongqing T, Wilmann PG, Reeve SB, Coetzer TH, Smith AI, Whisstock JC, Pike RN, Wijeyewickrema LC. The x-ray crystal structure of mannose-binding lectin-associated serine proteinase-3 reveals the structural basis for enzyme inactivity associated with the Carnevale, Mingarelli, Malpuech, and Michels (3MC) syndrome. J Biol Chem. 2013 Aug 2;288(31):22399-407. doi: 10.1074/jbc.M113.483875. Epub 2013 Jun 21. Erratum In: J Biol Chem. 2013 Sep 27;288(39):28307. Citation on PubMed or Free article on PubMed Central

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.