Warrior gene

A version of the primate monoamine oxidase-A gene has been referred to as the "warrior gene", initially in monkeys then in humans. Several different versions of the gene are found in different individuals, although a functional gene is present in most humans (except in a few individuals with Brunner syndrome).OMIM|309850|MONOAMINE OXIDASE A; MAOA.] There is not an additional warrior gene, rather the genotype associated with behavioural traits is shorter (30 bases) and may produce less MAO-A enzyme.cite journal |author=Sabol SZ, Hu S, Hamer D |title=A functional polymorphism in the monoamine oxidase A gene promoter |journal=Hum. Genet. |volume=103 |issue=3 |pages=273–9 |year=1998 |month=Sep |pmid=9799080 |doi= |url=http://link.springer.de/link/service/journals/00439/bibs/8103003/81030273.htm] The variation in this case is actually in a regulatory promoter region about 1000 bases from the start of the region that encodes the MAO-A enzyme. However, research studies emphasise that behaviour is dependent on both genes and the environment.cite journal |author=Caspi A, McClay J, Moffitt TE, "et al" |title=Role of genotype in the cycle of violence in maltreated children |journal=Science (journal) |volume=297 |issue=5582 |pages=851–4 |year=2002 |month=Aug |pmid=12161658 |doi=10.1126/science.1072290 |url=]

In 2006, a New Zealand researcher, Dr Rod Lea said that this variant (or genotype) of monoamine oxidase-A was over-represented in a small sample of current Māori. [ [http://www.nzherald.co.nz/section/story.cfm?c_id=1&ObjectID=10395334 Maori 'warrior' gene linked to aggression] ] This supported earlier studies that there are different proportions of variants in different ethnic groups. This is the case for many genetic variants, with 33% White/Non-Hispanic, 61% Asian/Pacific Islanders having the shorter promoter variant of the MAO-A gene. This was subsequently discussed in a number of articles in the New Zealand Medical Journal. [cite journal |author=Lea R, Chambers G |title=Monoamine oxidase, addiction, and the "warrior" gene hypothesis |journal=N. Z. Med. J. |volume=120 |issue=1250 |pages=U2441 |year=2007 |pmid=17339897 |doi= |url=http://www.nzma.org.nz/journal/120-1250/2441] [cite journal |author=Merriman T, Cameron V |title=Risk-taking: behind the warrior gene story |journal=N. Z. Med. J. |volume=120 |issue=1250 |pages=U2440 |year=2007 |pmid=17339896 |doi= |url=http://www.nzma.org.nz/journal/120-1250/2440]

Due to the sensitive political nature of the findings, and the standard peer review process, the research has been heavily scrutinized. Several objections have been raised, such as the small sample size, and the extrapolation of non-Maori studies to the Maori population. In addition, ideological objections were raised, as well as concerns about announcing such findings in the early stages of research. [ [http://www.nzherald.co.nz/category/story.cfm?c_id=204&objectid=10395491 Maori 'warrior gene' claims appalling, says geneticist] ] [ [http://www.hrc.govt.nz/assets/pdfs/publications/Hui%20Report%2006%20FINAL.pdf Hui Report 2006, Keynote presentation by Moana Jackson] ] [cite journal |author=Crampton P, Parkin C |title=Warrior genes and risk-taking science |journal=N. Z. Med. J. |volume=120 |issue=1250 |pages=U2439 |year=2007 |pmid=17339895 |doi= |url=http://www.nzma.org.nz/journal/120-1250/2439]

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