The XYY karyotype and criminality: a review

Testicular function in boys with 47,XYY and relationship to phenotype

An additional Y chromosome occurs in ~1 in 1,000 males, resulting in the karyotype 47,XYY. The phenotype includes tall stature, hypotonia, neuropsychiatric comorbidities, and an increased risk of infertility in adulthood. Little is known about testicular function in childhood and adolescence in 47,XYY. This cross-sectional study aimed to assess testicular function serum biomarkers, including total testosterone, inhibin B, and anti-mullerian hormone (AMH), in 82 boys with XYY (11.3 ± 3.8 years) compared with 66 male controls (11.6 ± 3.8 years). The association of testicular hormones with physical features, neuropsychological phenotype, and magnetoencephalography (MEG) was assessed with multiple linear regression models. Results indicate males with XYY have significantly lower inhibin B (median 84 pg/ml vs. 109 pg/ml, p = .004) and higher AMH (median 41 ng/ml vs. 29 ng/ml, p = .011); however, testosterone, testicular volume, and stretched penile length were not different from controls. In the exploratory analysis of relationships between hormone concentrations and phenotypic assessments, higher inhibin B concentrations were positively correlated with lower BMI and better cognitive, academic, and behavioral outcomes in the XYY group. Testosterone concentrations were positively associated with better behavioral outcomes in boys with XYY. Higher testosterone and inhibin B concentrations were also associated with shorter auditory latencies measured using magnetoencephalography (MEG) in XYY. With a few exceptions, testicular hormones were not associated with phenotypic outcomes in controls. In conclusion, there is evidence of subtle impaired testicular function in boys with XYY and a newly described relationship between measures of testicular function and some aspects of the XYY phenotype.

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.

Biological factors and crime: implications for forensic psychiatry

To summarize, we can say that (1) Criminal behavior, especially chronic criminal behavior, seems to be partly genetically predisposed; (2) An important task at this point is to attempt to determine the biological factors which predispose people to crime; and (3) We have related some tentative initial steps being taken in the study of the autonomic nervous system as one possible heritable, biological basis for the failure of normal social learning forces in inhibiting criminal behavior. Early in this paper we discussed the tenability of asserting criminal responsibility on individuals whose criminal behavior has a partly genetic etiology. But this special consideration seems to set biological factors apart as being in some unique causal category. In fact, genetic, physiological, and biochemical factors are causal agents in the same sense as family, social class, or neighborhood factors. Of course, criminal behavior (like all other behavior) must be caused; one class of causal variables is the biological category. The legal doctrine of responsibility is not challenged by identifying biological factors as partially determining crime any more than it is by findings of social causation. Only in cases in which abnormal biological factors are exceptionally powerful influences might responsibility be challenged. Such cases will be quite rare.

Sex chromosome disorders

A critical and comprehensive review of the major sex chromosome disorders. The introduction briefly outlines the cytogenetic background to these disorders and refers to earlier reviews. The paper then reviews the clinical and psychiatric aspects of the various chromosome disorders. Male and female phenotypes are dealt with separately, with emphasis on psychological and behavioural manifestations including antisocial behaviour. Medico-legal implications are also reviewed, as are the implications for research.

Height and personality characteristics of 47, XYY males in a sample of tall non-institutionalized males

A sample of 471 enlisted men 183 cm or taller serving in the US Navy, Coast Guard, and Marine Corps was screened for Y-chromosome aneuploidy by use of quinacrine fluorescence of peripheral blood smears. Two 47,XYY males were detected, resulting in a prevalence of 00425 or approximately 1 in 236. The prevalence of 47,XYY males (00331) in a number of samples of tall, non-institutionalized males is significantly higher than the incidence in newborn males (00061), indicating that 47,XYY males are disproportionately represented in tall male populations. The 47,XYY males had significantly higher scores than 46,XY males on the Schizophrenia, Schizophrenia+1K, and Prejudice scales of the Minnesota Multiphasic Personality Inventory and significantly lower scores on the Dominance scale. Since the probability that a randomly selected pair of subjects in the sample had four or more scale scores significantly different from the remainder of the group was greater than 05, it is possible that the differences between the 47,XYY and 46,XY males occurred by chance. On the other hand, one or more of these scales may measure personality dimensions on which non-institutionalized 47,XYY males may, in fact, differ from 46,XY males.

Chromosomal determinants of intermale aggressive behavior in inbred mice

A behavioral genetic system has been investigated in which the Y chromosome of DBA/1/Bg mice makes an incremental contribution to the adult aggression of B10D1F1 hybrid mice. Crosses with C57BL/10/Bg, C57BL/6/Bg, and DBA/2/Bg have identified a minimum of one incremental and one decremental (suppressor) genetic factor (in addition to the Y chromosome) which are autosomal and which affect the expression of adult intermale aggression in these strains.

Thirty-five males with double Y chromosome

Thirty-five males with double Y chromosome were studied. Among the features observed in certain subgroups of these 35 were a more than average height, minor vertebral abnormalities, abnormal seminiferous epithelium, minor EEG abnormalities, and a mean intelligence level significantly below the expected. Fifteen of the 35 were found in institutions for criminals. The frequency of XYY males among 1,500 criminal males was 8·67 per 1,000 compared with 1·24 per 1,000 among 6,455 randomly selected males in the general population. Males with double Y chromosome tended to have more difficulties at school, to be more mentally immature, to be more impulsive than their siblings, and to have more difficulty in making relationships with others.

Studies on the activity of the pituitary-gonadal axis in the XYY syndrome

Results are presented of pituitary gonadotrophic and testicular steroid hormone assays carried out on 11 phenotypic males with a 47, XYY karyotype. These results are compared with those from a control group of normal ambulant males and a group of patients with a 46, XY karyotype who were detained in a maximum security hospital.

Neurological anomalies in XYY males

A high incidence of men with the 47 XYY karyotype has been repeatedly demonstrated amongst inmates of prisons (Bartlett et al., 1968; Griffiths et al., 1967) and institutions of psychologically abnormal offenders (Jacobs et al., 1968; Casey et al., 1968). Although genetic surveys of the newborn suggest that there must be many more males with this karyotype who remain undetected in the general population, the high incidence of this karyotype amongst these highly selected groups remains unexplained. The initial hypothesis that the extra Y chromosome was associated with aggressiveness no longer appears tenable, at least in its extreme form, as studies indicate that men with this karyotype are less aggressive than other men in the same institution (Price and Whatmore, 1967). It has also been suggested (Hunter, 1966) that because of their increased stature they are more likely to be seen as aggressive and dangerous, and that emotional disturbances arise from problems consequent to being tall. Forssman and Hambert (1969) have suggested that some cerebral abnormality might account for the behaviour of these individuals, and point to reports of EEG abnormalities as being in keeping with this. In support of this idea, Daly (1969) has reported finding neurological abnormalities in 10 out of 12 XYY males that he examined. He further suggested that neurological deficits might prove valuable in identifying individuals of this karyotype. Criticism has been made of such conclusions (Kessler and Moos, 1970) on the grounds that all such studies have been carried out on patients in special institutions, and that the prevalence of similar abnormalities in the rest of these populations is not known. The following report describes neurological findings in 23 XYY men and in a group of patients with a 46 XY karyotype from the same institution, matched in respect of age (6 months), intelligence (15 points on WAIS), and length of stay (within two years). All patients were from Rampton and Moss Side Hospitals (two of the English Special Hospitals) and had been karyotyped in a previous survey (see Casey, 1971). Apart from those on anticonvulsant medication, all patients had been off drugs for at least the preceding four weeks. Controls and index cases were seen in a randomized order by one of us (M.J.G.H.) who did not know at the time of examination to which group the patient belonged. The neurological anomalies detected in the two groups are shown in the table below.