New gene variant linked to 'killer' mice

A single gene mutation can turn normal mice into ferocious killers, according to a new report.

Several years ago, Elizabeth Simpson discovered that mice with a mutation of the Nr2e1 gene are extremely aggressive, killing even their mates and siblings and attacking lab workers. Simpson, fellow researcher K. A. Young, and colleagues have now bred four generations of the mice, and report that both females and males who inherit copies of the gene from both parents are highly aggressive.

Simpson, who has dubbed the gene the "fierce mutation," says her research group found it remarkable that a variation in one gene could have such a powerful influence on behavior. "Even in a mouse," she says, "it's quite a surprise that a single gene would do this and be able to change the brain that much." The role of the Nr2e1 gene in humans is not known, but in mice, in addition to influencing behavior, it affects eye development, sense of smell, size, and brain structure.

Past research has reported that other gene variations affecting monoamine oxidase A or nitric oxide levels can also cause mice to become highly aggressive or sexually predatory (see related article, Crime Times, 1996, Vol. 2, No. 1, Page 4).

"Fierce: a new mouse deletion of Nr2e1; violent behaviour and ocular abnormalities are background-dependent," K. A. Young, M. L. Berry, C. L. Mahaffey, J. R. Saionz, N. L. Hawes, B. Chang, Q. Y. Zheng, R. S. Smith, R. T. Bronson, R. J. Nelson, and E. M. Simpson, Behavioural Brain Research, Vol. 132, No. 2, May 14, 2002, 145-58. Address: K. A. Young, Department of Biochemistry and Molecular Biology, Johns Hopkins School of Public Health, Baltimore, MD 21205.

"Attack of killer mice suggests violence is genetic," Carolyn Abraham, Globe and Mail (Canada), May 6, 2002.