Criminality in XYY and XXY men

Parental questions about sex chromosome aneuploidies regarding sex, gender, and sexual orientation as reported by genetic counselors in a prenatal setting

The introduction of cell-free DNA screening has resulted in increased prenatal identification of sex chromosome aneuploidies (SCAs). This study aimed to evaluate genetic counselor experiences disclosing SCAs positive prenatal screening or testing results and genetic counselor-reported parental questions regarding sex, gender, and sexual orientation. Forty-eight prenatal genetic counselors completed the survey. When asked to quantify their experiences, 97.9% of counselors reported disclosing a SCAs positive screen result within the previous year, and 81.3% disclosed a diagnostic result. Of those counselors, 53.8% reported always or often receiving parental questions about sex, 33% always or often about gender, and 25% always or often regarding sexual orientation. Counselors were asked to share examples of parental questions following a positive screen or diagnostic testing for SCAs. Parental questions were stratified by karyotype and content analysis revealed questions about the fetus' sex, anatomy, reproduction, being cisgender, gender expression, behavior, being transgender, and sexual orientation. The examples of parental questions provided by genetic counselors suggested some parents may have misconceptions about the intersection of SCAs with sex, gender, and sexual orientation following prenatal screening or diagnostic testing. The majority of counselors (83.3%) agreed to some extent that they desired further education on responding to parental questions about SCAs. Findings from this research suggest a need for genetic counseling strategies that accurately and respectfully discuss SCAs in the context of sex, gender, and sexual orientation with prenatal patients.

Primary gonadal failure

The term primary gonadal failure encompasses not only testicular insufficiency in 46,XY males and ovarian insufficiency in 46,XX females, but also those disorders of sex development (DSD) which result in gender assignment that is at variance with the genotype and gonadal type. In boys, causes of gonadal failure include Klinefelter and other aneuploidy syndromes, bilateral cryptorchidism, testicular torsion, and forms of 46,XY DSD such as partial androgen insensitivity. Causes in girls include Turner syndrome and other aneuploidies, galactosemia, and autoimmune ovarian failure. Iatrogenic causes in both boys and girls include the late effects of childhood cancer treatment, total body irradiation prior to bone marrow transplantation, and iron overload in transfusion-dependent thalassaemia. In this paper, a brief description of the physiology of testicular and ovarian development is followed by a section on the causes and practical management of gonadal impairment in boys and girls. Protocols for pubertal induction and post-pubertal hormone replacement - intramuscular, oral and transdermal testosterone in boys; oral and transdermal oestrogen in girls - are then given. Finally, current and future strategies for assisted conception and fertility preservation are discussed.

Cataract in a patient with 47,XYY sex chromosome aneuploidy

CASE REPORT

The case concerns a 16 year-old boy with a history of high myopia and unilateral congenital cataract, tall stature for age, facial dysmorphism, hypermobile metacarpal-phalangeal joints, as well as behavioural problems. The mother had a history of recurrent pregnancy loss. Chromosomal analysis of the peripheral blood lymphocytes reported 47,XYY.

DISCUSSION

Patients with sex chromosome aneuploidy 47,XYY have higher risk of congenital malformations, although ophthalmological anomalies are unusual. Evaluation of patients with tall stature and behavioural problems should include a chromosomal analysis in order to determine the aetiology.

Shifting syndromes: Sex chromosome variations and intersex classifications

The 2006 'Consensus statement on management of intersex disorders' recommended moving to a new classification of intersex variations, framed in terms of 'disorders of sex development' or DSD. Part of the rationale for this change was to move away from associations with gender, and to increase clarity by grounding the classification system in genetics. While the medical community has largely accepted the move, some individuals from intersex activist communities have condemned it. In addition, people both inside and outside the medical community have disagreed about what should be covered by the classification system, in particular whether sex chromosome variations and the related diagnoses of Turner and Klinefelter's syndromes should be included. This article explores initial descriptions of Turner and Klinefelter's syndromes and their subsequent inclusion in intersex classifications, which were increasingly grounded in scientific understandings of sex chromosomes that emerged in the 1950s. The article questions the current drive to stabilize and 'sort out' intersex classifications through a grounding in genetics. Alternative social and historical definitions of intersex - such as those proposed by the intersex activists - have the potential to do more justice to the lived experience of those affected by such classifications and their consequences.

Neuropsychology and socioeconomic aspects of Klinefelter syndrome: new developments

PURPOSE OF REVIEW

To summarize recent important studies on neuropsychology and epidemiology of Klinefelter syndrome. PubMed was searched for 'Klinefelter', 'Klinefelter's' and 'XXY' in titles and abstracts. Relevant studies were obtained and reviewed, as well as other articles selected by the authors.

RECENT FINDINGS

Klinefelter syndrome is the most common sex-chromosome disorder in humans, affecting one in 660 men. The key findings in Klinefelter syndrome are small testes, hypergonadotropic hypogonadism and cognitive impairment. Klinefelter syndrome scores significantly below education matched controls on a range of cognitive tests with verbal skills displaying the largest effects. Boys with Klinefelter syndrome are often in the need of speech therapy and many suffer from learning disability and may benefit from special education. New studies are elucidating aspects of cognitive functioning and suggesting that neuropsychological treatment may be of value. The socioeconomic status and educational level of Klinefelter syndrome is severely affected with many struggling to achieve any or only shorter education, resulting in low-income levels and early retirement. In addition, few become fathers and fewer live with a partner compared with controls. Medical treatment is mainly testosterone replacement therapy in order to alleviate acute and long-term consequences of hypogonadism, as well as, treating or preventing the frequent comorbidity.

SUMMARY

The neurocognitive phenotype of Klinefelter syndrome is being unraveled and the need for psychological and cognitive treatment in many cases is evident. The neurocognitive deficits no doubt influence the socioeconomic status of many Klinefelter syndrome patients, which is clearly inferior to age-matched controls.

Oral health management of a patient with 47,XYY syndrome

The 47,XYY syndrome is an aneuploidy (abnormal number) of sex chromosomes, where a human male receives an extra Y chromosome, making 47 chromosomes instead of the usual 46. Individuals with 47,XYY are usually physically normal and tend to be tall and thin. They are not at increased risk of mental retardation and cardiovascular diseases. They may have speech delay, hyperactivity and normal/decreased IQ level. Behavioural problems are not common in 47,XYY individuals. There have been reports that suggest the tooth-size increase in 47,XYY males is due to a direct genetic effect. The patient presented with multiple over-retained deciduous, unerupted permanent teeth and increased incidence of carious lesions may be attributed to decreased oral hygiene maintenance. The present article describes the medical and dental history along with the clinical management of oral health issues in an 18-year-old male patient with 47,XYY syndrome having normal physical structure and development.

Using information technology and social networking for recruitment of research participants: experience from an exploratory study of pediatric Klinefelter syndrome

Background

Recruiting pediatric samples for research may be challenging due to parental mistrust of the research process, privacy concerns, and family time constraints. Recruitment of children with chronic and genetic conditions may further complicate the enrollment process.

Objective

In this paper, we describe the methodological challenges of recruiting children for research and provide an exemplar of how the use of information technology (IT) strategies with social networking may improve access to difficult-to-reach pediatric research participants.

Methods

We conducted a cross-sectional descriptive study of boys between the ages of 8 and 18 years with Klinefelter syndrome. This study presented unique challenges for recruitment of pediatric participants. These challenges are illustrated by the report of recruitment activities developed for the study. We reviewed the literature to explore the issues of recruiting children for research using conventional and IT approaches. Success rates of conventional recruitment approaches, such as brochures, flyers in medical offices, and physician referrals, are compared with IT-based outreach. The IT approaches included teleconferencing via a Klinefelter syndrome support group, services of a Web-based commercial recruitment-matching company, and the development of a university-affiliated research recruitment website with the use of paid advertising on a social networking website (Facebook).

Results

Over a 3-month period, dissemination of over 150 recruitment brochures and flyers placed in a large urban hospital and hospital-affiliated clinical offices, with 850 letters to physicians and patients were not successful. Within the same period, face-to-face recruitment in the clinical setting yielded 4 (9%) participants. Using Web-based and social networking approaches, 39 (91%) agreed to participate in the study. With these approaches, 5 (12%) were recruited from the national Klinefelter syndrome advocacy group, 8 (19%) from local and teleconference support groups, 10 (23%) from a Web-based research recruitment program, and 16 (37%) from the university-affiliated recruitment website. For the initial 6 months, the university website was viewed approximately 2 to 3 times per day on average. An advertisement placed on a social networking site for 1 week increased website viewing to approximately 63 visits per day. Out of 112 families approached using all of these methods, 43 (38%) agreed to participate. Families who declined cited either travel distance to the study site (15, 22%) or unwillingness to disclose the Klinefelter syndrome diagnosis to their sons (54, 78%) as the reasons for nonparticipation.

Conclusions

Use of Web-based technologies enhances the recruitment of difficult-to-reach populations. Of the many approaches employed in this study, the university-affiliated recruitment website supported by a Facebook advertisement appeared to be the most successful. Research grant budgets should include expenses for website registration and maintenance fees as well as online advertisements on social networking websites. Tracking of recruitment referral sources may be helpful in planning future recruitment campaigns.

Criminality in men with Klinefelter's syndrome and XYY syndrome: a cohort study

OBJECTIVE

To investigate the criminal pattern in men between 15 and 70 years of age diagnosed with 47,XXY (Klinefelter's syndrome (KS)) or 47,XYY compared to the general population.

DESIGN

Register-based cohort study comparing the incidence of convictions among men with KS and with 47,XYY with age- and calendar-matched samples of the general population. Crime was classified into eight types (sexual abuse, homicide, burglary, violence, traffic, drug-related, arson and 'others').

SETTING

Denmark 1978-2006.

PARTICIPANTS

All men diagnosed with KS (N=934) or 47,XYY (N=161) at risk and their age- and calendar-time-matched controls (N=88 979 and 15 356, respectively).

RESULTS

The incidence of convictions was increased in men with KS (omitting traffic offenses) compared to controls with a HR of 1.40 (95% CI 1.23 to 1.59, p<0.001), with significant increases in sexual abuse, burglary, arson and 'others', but with a decreased risk of traffic and drug-related offenses. The incidence of convictions was significantly increased among men with 47,XYY compared to controls with a HR of 1.42 (95% CI 1.14 to 1.77, p<0.005) in all crime types, except drug-related crimes and traffic. Adjusting for socioeconomic variables (education, fatherhood, retirement and cohabitation) reduced the total HR for both KS and 47,XYY to levels similar to controls, while some specific crime types (sexual abuse, arson, etc) remained increased.

CONCLUSION

The overall risk of conviction (excluding traffic offenses) was moderately increased in men with 47,XYY or KS; however, it was similar to controls when adjusting for socioeconomic parameters. Convictions for sexual abuse, burglary, arson and 'others' were significantly increased. The increased risk of convictions may be partly or fully explained by the poor socioeconomic conditions related to the chromosome aberrations.

Reduced cortical inhibition in violent offenders: a study with transcranial magnetic stimulation

BACKGROUND

Aggression and violent behaviour are often regarded as a threat to society. Therefore, understanding violent behaviour has high social relevance. We performed a study with transcranial magnetic stimulation on a sample of violent offenders in order to measure cortical inhibition in the motor neuron system that is part of the frontal cortex.

METHODS

To investigate intracortical inhibition and intracortical facilitation, we conducted paired-pulse stimulation according to the technique of Kujirai and his group (see Method). The investigation sample comprised 62 right-handers: 32 prisoners who had committed severe violent crimes and 30 controls with no history of violence. All subjects were male and matched for age.

RESULTS

Using the paired-pulse paradigm with interstimulus intervals (ISI) of 1-15 ms, a reduced cortical inhibition (ISI: 3 ms) was found in the left cortex of violent offenders compared with control subjects.

CONCLUSIONS

These findings corroborate the hypothesis of inhibition deficits and frontal cortex dysfunction in violent offenders when compared with non-violent control subjects.

Genetic and hormonal control of bone volume, architecture, and remodeling in XXY mice

Klinefelter syndrome is the most common chromosomal aneuploidy in men (XXY karyotype, 1 in 600 live births) and results in testicular (infertility and androgen deficiency) and nontesticular (cognitive impairment and osteoporosis) deficits. The extent to which skeletal changes are due to testosterone deficiency or arise directly from gene overdosage cannot be determined easily in humans. To answer this, we generated XXY mice through a four-generation breeding scheme. Eight intact XXY and 9 XY littermate controls and 8 castrated XXY mice and 8 castrated XY littermate controls were euthanized at 1 year of age. Castration occurred 6 months prior to killing. A third group of 9 XXY and 11 XY littermates were castrated and simultaneously implanted with a 1-cm Silastic testosterone capsule 8 weeks prior to sacrifice. Tibias were harvested from all three groups and examined by micro-computed tomography and histomorphometry. Blood testosterone concentration was assayed by radioimmunoassay. Compared with intact XY controls, intact androgen-deficient XXY mice had lower bone volume (6.8% +/- 1.2% versus 8.8% +/- 1.7%, mean +/- SD, p = .01) and thinner trabeculae (50 +/- 4 µm versus 57 +/- 5 µm, p = .007). Trabecular separation (270 +/- 20 µm versus 270 +/- 20 µm) or osteoclast number relative to bone surface (2.4 +/- 1.0/mm2 versus 2.7 +/- 1.5/mm2) did not differ significantly. Testosterone-replaced XXY mice continued to show lower bone volume (5.5% +/- 2.4% versus 8.1% +/- 3.5%, p = .026). They also exhibited greater trabecular separation (380 +/- 69 µm versus 324 +/- 62 µm, p = .040) but equivalent blood testosterone concentrations (6.3 +/- 1.8 ng/mL versus 8.2 +/- 4.2 ng/mL, p = .28) compared with testosterone-replaced XY littermates. In contrast, castration alone drastically decreased bone volume (p < .001), trabecular thickness (p = .05), and trabecular separation (p < .01) to such a great extent that differences between XXY and XY mice were undetectable. In conclusion, XXY mice replicate many features of human Klinefelter syndrome and therefore are a useful model for studying bone. Testosterone deficiency does not explain the bone phenotype because testosterone-replaced XXY mice show reduced bone volume despite similar blood testosterone levels.

Genetic, hormonal, and metabolomic influences on social behavior and sex preference of XXY mice

XXY men (Klinefelter syndrome) are testosterone deficient, socially isolated, exhibit impaired gender identity, and may experience more homosexual behaviors. Here, we characterize social behaviors in a validated XXY mouse model to understand mechanisms. Sociability and gender preference were assessed by three-chambered choice tasks before and after castration and after testosterone replacement. Metabolomic activities of brain and blood were quantified through fractional synthesis rates of palmitate and ribose (GC-MS). XXY mice exhibit greater sociability than XY littermates, particularly for male mice. The differences in sociability disappear after matching androgen exposure. Intact XXY, compared with XY, mice prefer male mice odors when the alternatives are ovariectomized female mice odors, but they prefer estrous over male mice odors, suggesting that preference for male mice may be due to social, not sexual, cues. Castration followed by testosterone treatment essentially remove these preferences. Fractional synthesis rates of palmitate are higher in the hypothalamus, amygdala, and hippocampus of XXY compared with XY mice but not with ribose in these brain regions or palmitate in blood. Androgen ablation in XY mice increases fractional synthesis rates of fatty acids in the brain to levels indistinguishable from those in XXY mice. We conclude that intact XXY mice exhibit increased sociability, differences in gender preference for mice and their odors are due to social rather than sexual cues and, these differences are mostly related to androgen deficiency rather than genetics. Specific metabolic changes in brain lipids, which are also regulated by androgens, are observed in brain regions that are involved in these behaviors.

Diagnosis and mortality in 47,XYY persons: a registry study

Background

Sex chromosomal abnormalities are relatively common, yet many aspects of these syndromes remain unexplored. For instance epidemiological data in 47,XYY persons are still limited.

Methods

Using a national Danish registry, we identified 208 persons with 47,XYY or a compatible karyotype, whereof 36 were deceased; all were diagnosed from 1968 to 2008. For further analyses, we identified age matched controls from the male background population (n = 20,078) in Statistics Denmark. We report nationwide prevalence data, data regarding age at diagnosis, as well as total and cause specific mortality data in these persons.

Results

The average prevalence was 14.2 47,XYY persons per 100,000, which is reduced compared to the expected 98 per 100,000. Their median age at diagnosis was 17.1 years. We found a significantly decreased lifespan from 77.9 years (controls) to 67.5 years (47,XYY persons). Total mortality was significantly increased compared to controls, with a hazard ratio of 3.6 (2.6-5.1). Dividing the causes of deaths according to the International Classification of Diseases, we identified an increased hazard ratio in all informative chapters, with a significantly increased ratio in cancer, pulmonary, neurological and unspecified diseases, and trauma.

Conclusion

We here present national epidemiological data regarding 47,XYY syndrome, including prevalence and mortality data, showing a significantly delay to diagnosis, reduced life expectancy and an increased total and cause specific mortality.

The Danish draft board's intelligence test, Børge Priens Prøve: psychometric properties and research applications through 50 years

For over 50 years the Danish draft board has used the same test, Børge Priens Prøve (BPP) for cognitive abilities, involving four paper-and-pencil subtests, to assess suitability for conscription. The potential availability of test scores has been an invaluable resource for research into factors relating to intelligence. In this article the circumstances of the original development of the test are briefly presented, followed by a description of the four subtests and the conditions of testing, scoring and result registration. Over forty studies are identified, including some unpublished, which have explored the psychometric properties of the BPP and have shown the relationships between intelligence as measured by the BPP and a wide range of biological, social and health-related factors.

Neurocognitive outcomes of individuals with a sex chromosome trisomy: XXX, XYY, or XXY: a systematic review

AIM

To review systematically the neurodevelopmental characteristics of individuals with sex chromosome trisomies (SCTs).

METHOD

A bibliographic search identified English-language articles on SCTs. The focus was on studies unbiased by clinical referral, with power of at least 0.69 to detect an effect size of 1.0.

RESULTS

We identified 35 articles on five neonatally identified samples that had adequate power for our review. An additional 11 studies were included where cases had been identified for reasons other than neurodevelopmental concerns. Individuals with an additional X chromosome had mean IQs that were within broadly normal limits but lower than the respective comparison groups, with verbal IQ most affected. Cognitive outcomes were poorest for females with XXX. Males with XYY had normal-range IQs, but all three SCT groups (XXX, XXY, and XYY) had marked difficulties in speech and language, motor skills, and educational achievement. Nevertheless, most adults with SCTs lived independently. Less evidence was available for brain structure and for attention, social, and psychiatric outcomes. Within each group there was much variation.

INTERPRETATION

Individuals with SCTs are at risk of cognitive and behavioural difficulties. However, the evidence base is slender, and further research is needed to ascertain the nature, severity, and causes of these difficulties in unselected samples.

Methodological structure for aggression research

Kendler's seminal essay listed 8 major propositions outlining a philosophical framework for the entire field of psychiatry [Kendler (American Journal of Psychiatry 162:433-440, 2005)]. These propositions have grounded psychiatric research on a coherent conceptual basis. The field of aggression research needs a general conceptual framework that would help us to integrate the contributions of neurobiology, sociology, criminology, and other areas. All of Kendler's propositions are generally relevant in this respect. The aim of the current article is to develop specific applications of four of Kendler's propositions for aggression research. These four propositions are: "Psychiatry is irrevocably grounded in mental, first-person experiences", "Psychiatric disorders are etiologically complex, and we can expect no more "spirochete-like" discoveries that will explain their origin in simple terms", "Explanatory pluralism is preferable to monistic explanatory approaches, especially biological reductionism", and "Acceptance of Patchy Reductionism".

Bad nature, bad nurture, and testimony regarding MAOA and SLC6A4 genotyping at murder trials

Recent research-in which subjects were studied longitudinally from childhood until adulthood-has started to clarify how a child's environment and genetic makeup interact to create a violent adolescent or adult. For example, male subjects who were born with a particular allele of the monoamine oxidase A gene and also were maltreated as children had a much greater likelihood of manifesting violent antisocial behavior as adolescents and adults. Also, individuals who were born with particular alleles of the serotonin transporter gene and also experienced multiple stressful life events were more likely to manifest serious depression and suicidality. This research raises the question of whether testimony regarding a defendant's genotype, exposure to child maltreatment, and experience of unusual stress is appropriate to present during the guilt or penalty phases of criminal trials, especially when capital punishment is a consideration. The authors present their experience in genotyping criminal defendants and presenting genetic information at criminal trials.

Considering theories of aggression in an emergency department context

Internationally literature emphasises concern regarding the phenomenon of violence and aggression within the emergency field. This paper emphasises the important role education and training may play in reducing the risk of staff being exposed to violent or aggressive experiences. Furthermore, the paper emphasises, explores and discusses well recognised theories relating to aggression development. These theories can be used to explain both organisational strategies designed to minimise aggression in the emergency department and situational factors contributing to the development of aggressive interactions.

DABCO-Catalyzed Reaction of Allenic Esters and Ketones with Salicyl N-Tosylimines: Synthesis of Highly Functionalized Chromenes

[reaction: see text] DABCO-catalyzed reactions of salicyl N-tosylimines with ethyl 2,3-butadienoate and penta-3,4-dien-2-one proceed smoothly at room temperature in dichloromethane to give the corresponding chromenes in good to excellent yields.

Klinefelter's syndrome

Klinefelter's syndrome is the most common genetic cause of human male infertility, but many cases remain undiagnosed because of substantial variation in clinical presentation and insufficient professional awareness of the syndrome itself. Early recognition and hormonal treatment of the disorder can substantially improve quality of life and prevent serious consequences. Testosterone replacement corrects symptoms of androgen deficiency but has no positive effect on infertility. However, nowadays patients with Klinefelter's syndrome, including the non-mosaic type, need no longer be considered irrevocably infertile, because intracytoplasmic sperm injection offers an opportunity for procreation even when there are no spermatozoa in the ejaculate. In a substantial number of azoospermic patients, spermatozoa can be extracted from testicular biopsy samples, and pregnancies and livebirths have been achieved. The frequency of sex chromosomal hyperploidy and autosomal aneuploidies is higher in spermatozoa from patients with Klinefelter's syndrome than in those from normal men. Thus, chromosomal errors might in some cases be transmitted to the offspring of men with this syndrome. The genetic implications of the fertilisation procedures, including pretransfer or prenatal genetic assessment, must be explained to patients and their partners.

Klinefelter syndrome and its variants: an update and review for the primary pediatrician

Klinefelter syndrome is the most common chromosomal abnormality in humans. Recent prospective, unbiased studies have clarified many of the previous misconceptions associated with Klinefelter syndrome, thereby improving our recognition and management of this condition for affected individuals. The primary-care physician has an important role in caring for these individuals and their families by providing anticipatory guidance regarding issues relating to endocrinology, behavior, development, and preventive medical care. Furthermore, the primary-care giver can serve as a valuable source of support and advocacy for the family of a boy with Klinefelter syndrome. We review the current state of knowledge regarding Klinefelter syndrome and its variants, with an emphasis on medical and early developmental interventions.

Volumetric magnetic resonance imaging study of the brain in subjects with sex chromosome aneuploidies

OBJECTIVES

Cognitive impairment has been reported in people with sex chromosome aneuploides (SCAs) and it has been proposed that the presence of an extra sex chromosome may have an adverse effect on neurodevelopment. This study examines the hypothesis with structural MRI of the brain.

METHODS

Thirty two subjects with SCA (XXX (n=12), XYY (n=10), and XXY (n=10)) from a birth cohort study were matched groupwise for age, parental social class, and height with normal controls (13 female, 26 male). Brain MRI, measurements of IQ, and a structured psychiatric interview were performed.

RESULTS

The XXX females and XXY males had significantly smaller whole brain volumes than controls of the same phenotypic sex (p=0.003 and p</=0.05 respectively). The XXY group also had bilaterally enlarged lateral ventricles (p</=0.05). No significant differences were found between the XYY group and controls. IQ scores in all SCA groups were lower than in the control groups.

CONCLUSIONS

The main result of reduced brain volumes in XXX and XXY subjects, but not in XYY subjects, indicates that the presence of a supernumerary X chromosome has a demonstrable effect on brain development.

Cladistic association analysis of Y chromosome effects on alcohol dependence and related personality traits

Association between Y chromosome haplotype variation and alcohol dependence and related personality traits was investigated in a large sample of psychiatrically diagnosed Finnish males. Haplotypes were constructed for 359 individuals using alleles at eight loci (seven microsatellite loci and a nucleotide substitution in the DYZ3 alphoid satellite locus). A cladogram linking the 102 observed haplotype configurations was constructed by using parsimony with a single-step mutation model. Then, a series of contingency tables nested according to the cladogram hierarchy were used to test for association between Y haplotype and alcohol dependence. Finally, using only alcohol-dependent subjects, we tested for association between Y haplotype and personality variables postulated to define subtypes of alcoholism-antisocial personality disorder, novelty seeking, harm avoidance, and reward dependence. Significant association with alcohol dependence was observed at three Y haplotype clades, with significance levels of P = 0.002, P = 0.020, and P = 0.010. Within alcohol-dependent subjects, no relationship was revealed between Y haplotype and antisocial personality disorder, novelty seeking, harm avoidance, or reward dependence. These results demonstrate, by using a fully objective association design, that differences among Y chromosomes contribute to variation in vulnerability to alcohol dependence. However, they do not demonstrate an association between Y haplotype and the personality variables thought to underlie the subtypes of alcoholism.

Genetics of aggressive and violent behavior

This article develops the topic of the genetics of aggressive and violent behavior from three directions. Firstly, evidence from twin, family, and adoption studies will establish the case for the importance of genetically transmitted factors in the genesis of aggressivity from childhood through adulthood. Secondly, evidence from adoption studies will be presented to show that some environmental conditions interact with genetic factors in such a way as to suggest that the development of aggressivity requires that both genetic and environmental factors be present. Thirdly, additional and direct evidence of genetic factors in aggressivity is presented from the perspective of molecular genetics, where underlying biochemical mechanisms associated with aggressivity have been found to be caused by specific genes in animal models with confirmation of similar physiologic mechanisms in humans.

Mean genes and the biology of aggression: a critical review of recent animal and human research

Recent genetic work has suggested that abnormalities in serotonin biochemistry are directly causally linked to aggressive behavior, and there appears to be a consensus in the psychiatric literature that low levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid are specifically associated with impulsive violent behavior. We review the limitations of the genetic studies and conduct a meta-analysis of 39 studies linking 5-HIAA to aggression in humans. No differences in mean 5-HIAA levels were found between groups of violent impulsive psychiatric patients and groups of subjects diagnosed with other psychiatric or medical conditions not considered to involve violence once these levels had been corrected for three nonpsychiatric sources of variation (age, sex and height). However, mean 5-HIAA levels in both of these groups were lower than the mean corrected level in groups of normal healthy volunteers. The results confirm an association between low 5-HIAA levels and psychiatric disorders, but fail to support any specific relationship between low 5-HIAA levels and impulsive aggression or criminality. It is premature and misleading to speak of "mean genes" (Hen 1996) or a specific neurochemistry of aggressive behavior.

Legal implications of genetics and crime research

Two controversial topics dominate discussions of the legal implications of genetics and crime research; (1) the viability and politics of such research, which has sparked fervent debate in the USA; and (2) the current status of new or atypical criminal law defences, which would include a genetic-defect defence to criminal behaviour. This chapter begins by examining the scientifically discredited XYY chromosome syndrome defence, the major genetic-defect defence that defendants have attempted, albeit unsuccessfully. It then focuses on attorneys' efforts to test for evidence of genetic abnormality in the recent and highly publicized case involving convicted murderer Stephen Mobley, whose family history reveals four generations of violent, aggressive and behaviourally disordered men and women. Mobley is currently appealing his death sentence before the Georgia Supreme Court on the basis that the trial court denied his request both to have genetic testing performed and to have such testing allowed as evidence into court. This chapter concludes by emphasizing that the question is not whether genetic evidence will ever be admitted into court, but when and under what kinds of circumstances. No doubt, genetic evidence, and comparable kinds of biological evidence, will have a major impact on juries when such evidence is more fully accepted by the legal and scientific communities.

Intelligence and achievement in children with extra X aneuploidy: a longitudinal perspective

Forty-seven children (35 male, 12 female) identified as having a supernumerary X chromosome by neonatal screening were studied psychologically from childhood to late adolescence. This paper compares their findings relative to sibling controls on tests of intelligence and achievement collected over a 14-year period. Children with a supernumerary X chromosome were found to score consistently below controls on Verbal IQ and subtests comprising the Verbal Comprehension factor but they did not differ on Performance IQ, which was in the normal range. At all ages, they showed poorer reading and arithmetic achievement; relative risk for reading and arithmetic impairment was 2.6 and 2.6 in males and 1.1 and 1.7 in females. Males with an extra X chromosome were more likely to receive special education than females, who more often failed a grade. Academic achievement was not affected in aneuploid children with higher levels of intelligence. Overall, these results suggest milder impairment than previously reported, particularly among trisomy X females.

Disorders of sexual development

Over the past 6 years, the structures of four key genes involved in sexual differentiation have been identified (see Figure 2). Mutations within these genes have been demonstrated to cause a significant percentage of the disorders of sexual differentiation described in this chapter. It should be noted, however, that there are significant numbers of patients with these disorders in whom no mutation in any of these genes has yet been characterized. It is probable that further genes involved in sexual differentiation will be identified and shown to be the cause of a number of these diseases.

The genetics of mental retardation

Individuals affected by mental retardation are a clinically and aetiologically heterogeneous group. This heterogeneity is particularly highlighted when we consider the genetics of mental retardation. Recent advances in molecular genetic techniques have enabled us to understand more about the molecular basis of several genetic syndromes associated with mental retardation. In contrast, where there is no discrete cause, the interplay of genetic and environmental influences remains poorly understood.

Growth during puberty in the XYY boy

The availability of a cohort of eight unselected XYY boys identified by newborn cytogenetic screening has enabled their growth to be studied longitudinally in comparison with controls from the same population. While no difference had been found in dimensions at birth, increased height velocity in childhood resulted in the XYY boys being 7.6 cm taller at the onset of their pubertal growth spurt. Increased intensity of growth at puberty with a peak height velocity of 10.6 cm/year contributed to their adult height of 188.1 cm. XYY boys showed twice the male-female difference in height implying that genes on the Y chromosome exert a quantitative effect on the sexual dimorphism of growth.

From abuse to violence: psychophysiological consequences of maltreatment

This paper reviews the psychophysiological literature related to violent behaviors. It explores the interactions of environmental influences, pain, stressors, hormones, and neurotransmitters. It presents ways in which maltreatment in the form of abuse or neglect exacerbates preexisting psychobiological vulnerabilities. It proposes that whatever forces increase impulsivity and irritability, engender hypervigilence and paranoia, diminish judgment and verbal competence, and curtail the recognition of pain in the self and others, will enhance violence, and presents evidence that maltreatment has all of these effects.

The genetics of personality disorder

Most measurable aspects of normal personality appear to be at least moderately heritable, with direct evidence coming from family, twin and adoption studies and indirect support deriving from psychophysiological research and breeding experiments on animals. Interestingly, genetic studies also shed light on the environmental sources of variation in personality and suggest that shared family environment rarely, if ever, has any positive effect on similarity between relatives. Despite problems of classification, and variations in the use of terms, a survey of the literature provides reasonably consistent evidence of a genetic contribution to several categories of abnormal personality, which we here divide into three groups, antisocial, anxious/avoidant, and schizoid-schizotypal personalities. However, personality disorders are complex traits that do not show simple mendelian patterns of inheritance and so far molecular genetics has been of no help in understanding their aetiology. Fortunately, techniques are now becoming available that enable the detection and potential localisation of genes of small effect and which may help elucidate the molecular basis even of (probably) polygenic traits such as abnormal personality.

A review of Klinefelter's syndrome in children and adolescents

Klinefelter's syndrome (XXY syndrome) has been defined as the spectrum of phenotypic features resulting from a sex chromosome complement that includes two or more X chromosomes and one or more Y chromosomes. Cytogenetic surveys conducted across the world have identified a sizable population of XXY males, who have been studied extensively from the newborn period through adolescence. The longitudinal studies of these boys have produced an accurate and reliable account of the growth and development of the XXY male. There now exists a growing body of knowledge that suggests that XXY boys often experience language deficits, neuromaturational lag, academic difficulties, and psychological distress, which may be reduced or ameliorated by early identification, anticipatory guidance, and proper medical management.

Behavioral genetic methods

Traditional behavioral genetic methods involve the use primarily of family, twin, and adoption correlations to estimate the relative contributions of genetic and environmental influences in the etiology of individual differences. These methods and representative results for personality are described. However, newer methods are emphasized: structural models and model-fitting, multivariate analysis, genetic change and continuity in development, shared and non-shared components of environmental variance, and genetic components of "environmental" variation. Because most applications of these behavioral genetic methods to the study of personality involve self-report omnibus questionnaires, an important direction for future research in this area is to use these methods to explore new issues and new measures that have emerged from personality theory and research during the past decade.

Prospective study of attainment of social class of severely obese subjects in relation to parental social class, intelligence, and education

Cross sectional population studies have shown that subjects who are severely obese are of lower social class than comparable subjects who are not obese. This may be ascribed to lower parental social class, poorer education, and lower intelligence test scores of the obese subjects. In this study based on 242 633 draftees appearing before the draft board in Copenhagen between 1956 and 1977, 1144 extremely overweight men (body mass index greater than or equal to 31 kg/m2) were compared with 2123 young men randomly chosen from the remainder of the population. The two groups were followed up for an average period of 12 X 5 years, after which time their occupation was obtained from the National Population Register. Social class was derived from a ranking of occupations based on prestige from 0 (unskilled, manual worker) to 7 (for example, judge, professor). Among the obese subjects, only 300 (30%) out of 1006 attained a position above social class 2, compared with 988 (51%) out of 1948 in the control group. At each level of education and intelligence test score, as registered at the draft board, the obese subjects still showed a significantly lower attainment of social class than the controls. Inclusion of parental social class, information which was available for part of the population, did not eliminate the difference in attainment of social class. The results of this study show that obese subjects not only suffer from a higher risk of somatic diseases but have to live with a social handicap that is independent of parental social class, intelligence, and education.