Open Access Research BMJ Open: first published as 10.1136/bmjopen-2011-000650 on 22 February 2012. Downloaded from Criminality in men with Klinefelter’s syndrome and XYY syndrome: a cohort study Kirstine Stochholm,1 Anders Bojesen,2 Anne Skakkebæk Jensen,1 Svend Juul,3 Claus Højbjerg Gravholt1 To cite: Stochholm K, ABSTRACT ARTICLE SUMMARY Bojesen A, Jensen AS, et al. Objective: To investigate the criminal pattern in men Criminality in men with between 15 and 70 years of age diagnosed with 47, Article focus Klinefelter’s syndrome and XXY (Klinefelter’s syndrome (KS)) or 47,XYY - To investigate crime rates of men with an extra XYY syndrome: a cohort compared to the general population. study. BMJ Open 2012;2: sex chromosome (47,XXY and 47,XYY). Based e000650. doi:10.1136/ Design: Register-based cohort study comparing the on previous small studies, we hypothesised that bmjopen-2011-000650 incidence of convictions among men with KS and with an increased crime rate would be present in men 47,XYY with age- and calendar-matched samples of with an extra sex chromosome and investigated < Prepublication history and the general population. Crime was classified into eight this in a nationwide registry study. additional materials for this types (sexual abuse, homicide, burglary, violence, paper are available online. To traffic, drug-related, arson and ‘others’). Key messages view these files please visit - Setting: Denmark 1978e2006. Using a nationwide approach, we show that men the journal online (http://dx. diagnosed with KS (47,XXY) and 47,XYY are Participants: All men diagnosed with KS (N¼934) or doi.org/10.1136/ more frequently convicted for sexual abuse, 47,XYY (N¼161) at risk and their age- and calendar- bmjopen-2011-000650). burglary, arson and other reasons. Traffic time-matched controls (N¼88 979 and 15 356, offenses are seen less frequently in both groups. Received 21 November 2011 respectively). - Whether early diagnosis and improved clinical Accepted 2 February 2012 The incidence of convictions was increased in Results: care can lead to a decrease in convictions is not men with KS (omitting traffic offenses) compared to This final article is available clear. controls with a HR of 1.40 (95% CI 1.23 to 1.59, for use under the terms of - The increased crime rate may be partly or fully p<0.001), with significant increases in sexual abuse, http://bmjopen.bmj.com/ the Creative Commons mediated by poor socioeconomic conditions. Attribution Non-Commercial burglary, arson and ‘others’, but with a decreased risk 2.0 Licence; see of traffic and drug-related offenses. The incidence of Strengths and limitations of this study http://bmjopen.bmj.com convictions was significantly increased among men - The study clearly delineates a pattern of with 47,XYY compared to controls with a HR of 1.42 increased crime rates among men diagnosed (95% CI 1.14 to 1.77, p<0.005) in all crime types, with an extra sex chromosome. The strength of except drug-related crimes and traffic. Adjusting for the present study is the large number of men socioeconomic variables (education, fatherhood, with sex chromosomes and the large control retirement and cohabitation) reduced the total HR for group and the merging of several registries. both KS and 47,XYY to levels similar to controls, while - The limitations are that we were not able to on September 24, 2021 by guest. Protected copyright. some specific crime types (sexual abuse, arson, etc) control for concomitant medicinal use, especially remained increased. testosterone use in KS, nor to include clinical Conclusion: The overall risk of conviction (excluding data. traffic offenses) was moderately increased in men with 1 47,XYY or KS; however, it was similar to controls when e Department of affects 167 per 100 000 men,1 3 while the Endocrinology and Internal adjusting for socioeconomic parameters. Convictions Medicine, Aarhus University for sexual abuse, burglary, arson and ‘others’ were prevalence estimates of 47,XYY are highly Hospital NBG, Aarhus C, significantly increased. The increased risk of variable, ranging in live born men from 26 4 5 Aarhus, Denmark convictions may be partly or fully explained by the per 100 000 to 375 per 100 000, although 2 6 Department of Clinical poor socioeconomic conditions related to the many are not diagnosed or diagnosed late. Genetics, Vejle Hospital, chromosome aberrations. Both KS and 47,XYY are much more frequent Sygehus Lillebaelt, Vejle, 7 Denmark when studied in a tall population, which is 3Department of readily explained by the presence of addi- Epidemiology, School of tional copies of the SHOX gene (and Public Health, Aarhus INTRODUCTION possibly also other genes related to stature) University, Aarhus, Denmark The sex chromosome trisomies 47,XXY in men with KS and 47,XYY.8 As with 47,XYY, Correspondence to (Klinefelter’s syndrome (KS)) and 47,XYY many KS are not diagnosed, and a consider- Dr Claus Højbjerg Gravholt; are the most common male sex chromosome able delay in diagnosis exists for those who [email protected] aneuploidies compatible with live birth. KS get a diagnosis.2 Stochholm K, Bojesen A, Jensen AS, et al. BMJ Open 2012;2:e000650. doi:10.1136/bmjopen-2011-000650 1 Convictions and sex chromosome aberrations BMJ Open: first published as 10.1136/bmjopen-2011-000650 on 22 February 2012. Downloaded from The 47,XYY sex chromosome abnormality has been Register, Statistics Denmark and the Danish Central described in various settings6 9 since the first descrip- Crime Registry. tions of a group of men with 47,XYY in 1965 by Jacobs et al10 who conducted a chromosome survey of male Study population patients at the State Hospital in Carstairs, Scotland, and Using the Danish Cytogenetic Central Register, we found that men with the 47,XYY karyotype were partic- identified all men diagnosed with a karyotype compat- ularly frequent among inmates in penal institutions. ible with KS, 47,XYY or variants thereof in Denmark by During the 1960s and 1970s, studies of persons with KS January 2009. These men are hereafter referred to as and 47,XYY identified an increased frequency in hospi- index-persons. The register was founded in 1967 and tals for mentally handicapped,11 and men with 47,XYY contains information regarding all cytogenetic analyses seemed to be over-represented in prisons.12 Several of performed in Denmark since 1960, including date of these studies reported a general increased rate of crim- diagnosis. Unique identification numbers (ID numbers) inal behaviour and increased crime rates among both from the Civil Registration System enabled identification cohorts, especially due to sexual crimes.13 These studies of every single person diagnosed with an aberrant were associated with selection problems as they investi- chromosomal analysis. ID numbers are given to all gated institutionalised individuals. Two relatively new Danish citizens since 1968. The ID numbers ensured studies of criminal behaviour among sex chromosome a one-to-one linkage between the registries. trisomies have been published. Go¨tz et al14 found an increased rate of criminal behaviour among persons with Controls 47,XYY but not among persons with KS. Another study For each index-person, Statistics Denmark identified from 198815 linked young KS males with arson. However, up to 100 age- and calendar-time-matched controls both studies include a very limited number of persons. (matched on month and year of birth) from the male The study by Witkin et al7 in tall persons concluded that background population. All dates of emigration and there was no evidence of an increased crime rate among death were retrieved. All controls were alive and living in KS and 47,XYY, but again with very few study subjects. Denmark when their index-person was diagnosed. All Long-term follow-up of a cohort of KS (n¼19) and 47, controls emigrated or deceased before the index-person XYY (n¼19) indicated that persons with 47,XYY had turned 15 years were excluded. a fourfold increase in convictions, mostly due to minor offenses.16 All investigations conducted so far on this Convictions issue are limited by the study of selected groups, either The Danish Central Crime Register has previously been described as possibly the most thorough, comprehensive institutionalised or clinic patients, in addition to meth- 17 odological shortcomings, such as self-report of crimes, and accurate crime register in the Western world. Since http://bmjopen.bmj.com/ poorly defined definition of crime type and poorly the register was digitalised on 1 November 1978, all defined control groups. All studies have also been charges and decisions for any reported offense in conducted in very small groups comprising <20 persons Denmark have been registered. We had access to annual with a chromosome abnormality. The full spectrum of all information, and a person could be registered with types of crime has never been reported. As mentioned, multiple convictions the same year. We defined 1 July the diagnosis of both syndromes is usually delayed and more relevant year as the date of the conviction. The study than half of the expected individuals are never diag- period was from 1 November 1978 to 31 December 2006, nosed,26and a more thorough knowledge of all aspects as 2006 was last year with available information. on September 24, 2021 by guest. Protected copyright. these syndromes would most likely facilitate earlier In Denmark, the age of criminal responsibility is diagnosis and possibly better clinical care. 15 years. All solved criminal acts committed by individ- In order to examine the crime characteristics of men uals born after 1 November 1963 has been registered in with KS and 47,XYY, we undertook the present nation- the crime register. We considered only persons between wide study, focusing not only on the total number of 15 and 70 years during the study period to be at risk of convictions but also on various crime types.