1. ¹Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
2. ²Department of Forensic Psychiatry, University of Eastern Finland, Niuvanniemi Hospital, Kuopio, Finland
3. ³National Institute for Health and Welfare, Helsinki, Finland
4. ⁴Stanford University Center for Sleep Sciences, Palo Alto, CA, USA
5. ⁵Department of Psychiatry, University of Helsinki, Institute of Clinical Medicine, Helsinki, Finland
6. ⁶Department of Psychiatry, Helsinki University Central Hospital, Helsinki, Finland
7. ⁷Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, England
8. ⁸Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
9. ⁹Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
10. ¹⁰Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland
11. ¹¹Psychiatric & Neurodevelopmental Genetics Unit, Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
12. ¹²Social Psychiatry Unit, School of Health Sciences, University of Tampere, Finland
13. ¹³Psychiatric Hospital for Prisoners, Turku, Finland
14. ¹⁴University of Turku, Turku, Finland
15. ¹⁵Finnish Genome Center, Helsinki, Finland
16. ¹⁶The Criminal Sanctions Agency, Helsinki, Finland
17. ¹⁷University of Eastern Finland, Bioinformatics Center, Kuopio, Finland
18. ¹⁸Laboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, Rockville, MD, USA

Correspondence: Professor J Tiihonen, Karolinska Institutet, Department of Clinical Neuroscience, Byggnad R5, Stockholm, S-171 76, Sweden; Professor T Paunio, National Institute for Health and Welfare, PO Box 30, FI-00271, Finland. E-mail: jari.tiihonen@ki.se or tiina.paunio@thl.fi

¹⁹These authors contributed equaliy to this work.

Received 26 June 2014; Revised 25 August 2014; Accepted 28 August 2014
Advance online publication 28 October 2014

Abstract

In developed countries, the majority of all violent crime is committed by a small group of antisocial recidivistic offenders, but no genes have been shown to contribute to recidivistic violent offending or severe violent behavior, such as homicide. Our results, from two independent cohorts of Finnish prisoners, revealed that a monoamine oxidase A (MAOA) low-activity genotype (contributing to low dopamine turnover rate) as well as the CDH13 gene (coding for neuronal membrane adhesion protein) are associated with extremely violent behavior (at least 10 committed homicides, attempted homicides or batteries). No substantial signal was observed for either MAOA or CDH13 among non-violent offenders, indicating that findings were specific for violent offending, and not largely attributable to substance abuse or antisocial personality disorder. These results indicate both low monoamine metabolism and neuronal membrane dysfunction as plausible factors in the etiology of extreme criminal violent behavior, and imply that at least about 5–10% of all severe violent crime in Finland is attributable to the aforementioned MAOA and CDH13 genotypes.