In 1978, behavioral scientist Han Brunner interviewed a female patient at a hospital in Nijmegen in the Netherlands who was concerned about the extremely aggressive and violent behavior of men from his family. This family had produced five generations of men who had been victims of attempted murders and rapists dating back a hundred years to 1870. [2] As only the men in this family exhibited these antisocial and psychopathic tendencies, Brunner hypothesized the hypothesis that it was most likely an X-linked genetic mutation, as the female in the family has two [1]Through linkage analysis of familial DNA, Dr. Brunner's team had discovered that the specific gene actually existed on the short arm of the X chromosome. The mutated gene produced an inactive form of monoamine oxidase A which would normally help break down neurotransmitters in the brain. [1] This may explain why antisocial behavior among men is much more prevalent than among women. [8][9][10]The mutations present in the Brunner studies are extremely rare as this is the only known case of a completely nonfunctional MAOA. [2]However, this discovery had led to the identification of two other, much more common alleles encoding this particular gene. These two alleles are MAOA-H (high activity MAOA) and MAOA-L (low activity MAOA). [2] There is a clear correlation between the physiological and chemical changes in the brain associated with men carrying the low-activity MAOA gene. Since the brains of males carrying the MAOA-L allele are bathed in excess dopamine and serotonin from birth, the brain adapts by becoming less sensitive to these neurotransmitters, thereby decreasing activity in areas keys to the brain that coordinate aggression and reduce capacity...... middle of paper ......ychopath Inside: A neuroscientist's personal journey into the dark side of the brain. Penguin.[7] Klug, W., Cummings, M., Spencer, C., Palladino M. (2012) Concepts in Genetics: Tenth Edition. Pearson's Education, Inc.[8] American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised. Washington, DC, American Psychiatric Association, 1987.[9] Jim Fallon: Exploring the Mind of a Killer (2009) Ted: Ideas Worth Spreading http://www.ted.com/talks/jim_fallon_exploring_the_mind_of_a_killer.html [10] James Fallon: Confessions of a pro-social psychopath. (June 2011) World Science Festival http://worldsciencefestival.com/videos/moth_confessions_of_a_pro_social_psychopath [11] Blair, RJR (2007). The amygdala and ventromedial prefrontal cortex in morality and psychopathy. Trends in cognitive science, 11(9), 387-392.