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


Reviewed May 2010

What is the official name of the MCM6 gene?

The official name of this gene is “minichromosome maintenance complex component 6.”

MCM6 is the gene's official symbol. The MCM6 gene is also known by other names, listed below.

What is the normal function of the MCM6 gene?

The MCM6 gene provides instructions for making part of the MCM complex, a group of proteins that functions as a helicase. Helicases attach to particular regions of DNA and temporarily unwind the two spiral strands of these molecules. When a cell prepares to divide to form two cells, helicases unwind the DNA so that it can be copied. The DNA that makes up the chromosomes is duplicated (replicated) so that each new cell will get a complete set of chromosomes. Helicases are also involved in the production of RNA, a chemical cousin of DNA.

How are changes in the MCM6 gene related to health conditions?

lactose intolerance - course of condition modified by variations in the MCM6 gene

A specific DNA sequence within the MCM6 gene called a regulatory element helps control the activity (expression) of a nearby gene called LCT. The LCT gene provides instructions for making an enzyme called lactase. This enzyme helps to digest lactose, a sugar found in milk and other dairy products. Lactose intolerance in adulthood is caused by gradually decreasing expression of the LCT gene after infancy, which occurs in most humans.

At least four variations have been identified in the regulatory element that modulates LCT gene expression. These variations change single DNA building blocks (nucleotides) in the regulatory element. Each of the variations results in sustained lactase production in the small intestine and the ability to digest lactose throughout life. People without these changes have a reduced ability to digest lactose as they get older, resulting in the signs and symptoms of lactose intolerance.

Where is the MCM6 gene located?

Cytogenetic Location: 2q21

Molecular Location on chromosome 2: base pairs 135,839,626 to 135,876,477

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The MCM6 gene is located on the long (q) arm of chromosome 2 at position 21.

The MCM6 gene is located on the long (q) arm of chromosome 2 at position 21.

More precisely, the MCM6 gene is located from base pair 135,839,626 to base pair 135,876,477 on chromosome 2.

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

Where can I find additional information about MCM6?

You and your healthcare professional may find the following resources about MCM6 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 MCM6 gene or gene products?

  • DNA replication licensing factor MCM6
  • MCG40308
  • MCM6 minichromosome maintenance deficient 6 (MIS5 homolog, S. pombe)
  • minichromosome maintenance deficient 6 homolog
  • minichromosome maintenance deficient (mis5, S. pombe) 6
  • Mis5
  • MIS5 homolog
  • P105MCM

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

What glossary definitions help with understanding MCM6?

cell ; DNA ; DNA replication ; enzyme ; gene ; gene expression ; helicase ; intestine ; RNA

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


  • Enattah NS, Jensen TG, Nielsen M, Lewinski R, Kuokkanen M, Rasinpera H, El-Shanti H, Seo JK, Alifrangis M, Khalil IF, Natah A, Ali A, Natah S, Comas D, Mehdi SQ, Groop L, Vestergaard EM, Imtiaz F, Rashed MS, Meyer B, Troelsen J, Peltonen L. Independent introduction of two lactase-persistence alleles into human populations reflects different history of adaptation to milk culture. Am J Hum Genet. 2008 Jan;82(1):57-72. doi: 10.1016/j.ajhg.2007.09.012. (
  • Ingram CJ, Mulcare CA, Itan Y, Thomas MG, Swallow DM. Lactose digestion and the evolutionary genetics of lactase persistence. Hum Genet. 2009 Jan;124(6):579-91. doi: 10.1007/s00439-008-0593-6. Epub 2008 Nov 26. (
  • Ingram CJ, Raga TO, Tarekegn A, Browning SL, Elamin MF, Bekele E, Thomas MG, Weale ME, Bradman N, Swallow DM. Multiple rare variants as a cause of a common phenotype: several different lactase persistence associated alleles in a single ethnic group. J Mol Evol. 2009 Dec;69(6):579-88. doi: 10.1007/s00239-009-9301-y. Epub 2009 Nov 24. (
  • Itan Y, Jones BL, Ingram CJ, Swallow DM, Thomas MG. A worldwide correlation of lactase persistence phenotype and genotypes. BMC Evol Biol. 2010 Feb 9;10:36. doi: 10.1186/1471-2148-10-36. (
  • Järvelä IE. Molecular genetics of adult-type hypolactasia. Ann Med. 2005;37(3):179-85. Review. (
  • NCBI Gene (
  • Olds LC, Sibley E. Lactase persistence DNA variant enhances lactase promoter activity in vitro: functional role as a cis regulatory element. Hum Mol Genet. 2003 Sep 15;12(18):2333-40. Epub 2003 Jul 22. (
  • Robayo-Torres CC, Nichols BL. Molecular differentiation of congenital lactase deficiency from adult-type hypolactasia. Nutr Rev. 2007 Feb;65(2):95-8. Review. (


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: May 2010
Published: February 1, 2016