Behavioral implications of the human XYY genotype

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.

Follow-up till age 3--4 of unselected children with sex chromosome abnormalities

Follow-up examination of 15 unselected children with aneuploid sex chromosome abnormalities has been made till between the age of 2 1/2 and 5 years. The mental development of the 15 children was in all cases within the normal range, but there was a tendency to some differences compared with their siblings.

Chromosome survey of new patients admitted to the four maximum security hospitals in the United Kingdom

In a survey of male patients admitted to the four maximum security hospitals in the United Kingdom during 1972 and 1973, 26 out of 611 (4.26%) karyotyped were found to have chromosome abnormalities. Of these, 13 (2.13%) had a 47,XYY abnormality; 5 (0.8%) were chromatin positive but two of these had cell lines that included an extra Y chromosome, one being a 48XXYY male and the other a mosaic 48,XXYY/XYY. Eight patients with autosomal abnormalities included two with Down's syndrome and a 47,XY,+21 karyotype, two with small supernumerary chromosomes, 47,XY+mar, and two with inherited balanced translocation. As in the prevalence studies of patients in these high secruity hospitals, the significant finding was the very high frequency of males with extra Y chromosomes. In this survey, it was most marked in the younger patients and particularly in those who were aged 20 years or less (approximately 6%). As a group the XYY males were therefore significantly younger than all other male admissions. As in previous surveys thay were also significantly taller and 60% were 185 cm or more in height. There were no other distinguishing physical characteristics associated with the 47,XYY karytype. In all but two patients the behaviour disturbances were attributable to psychopathic disorders and mental subnormality was diagnosed no more frequently than in the total population studied (approximately 50%).

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.

Social class and frequency of XYY and XXY

The karyotype and paternal social class were determined for 10,348 consecutively born males. No significant difference in paternal social class was associated with the occurrence of the XYY or the XXY karyotype. This argues against the suggestion that socioeconomic factors significantly affect the frequency of the nondisjunctional events leading to these chromosome abnormalities.

Schizophrenia in a 47,XYY male

A case of schizophrenia in a 47,XYY male diagnosed according to strict phenomenological criteria is presented. The authors suggest that the 47,XYY chromosome anomaly should be added to the list of possible causes of symptomatic schizophrenia, and express the hope that future investigations of the effects of an extra Y chromosome in brain function will yield clues as to the aetiology of idiopathic schizophrenia.

Testosterone production by XYY subjects

A study of plasma concentration (P1T, ng/ml), metabolic clearance rate (MCRT, L/day) and blood production rate (PBT, mg/day) was done on seven XYY subjects of various ages and four pair-matched control XY subjects by a radioinfusion technique of 1,2-3H-testosterone. Although MCRT showed no significant difference between the groups, P1T and PBT were significantly lower (P less than 0.05) in XYY subjects. Therefore, increased aggressive behavior of the XYY subjects can not be attributed to increased levels or production rates of testosterone.

XYY individuals in a special school

The steady stream of publications on the XYY syndrome, including recent papers by Christensen and Nielsen (1973) and a comprehensive review by Hook (1973), demonstrates clearly that confirmation or refutation of the relationship in this syndrome between dull intelligence, even mental deficiency, and impulsive or delinquent behaviour requires further evidence. In an attempt to supply such evidence this report presents psychological and anthropometric information about five XYY subjects detected from amongst attenders at the Special School in the city of Aberdeen.

Sex chromosome aneuploidy among men in three Swedish hospitals for the mentally retarded and maladjusted

In the mid-1960.s, reports came from Scotland and England of a high frequency of gonosomal aberrations among male patients in maximum security hospitals (Jacobs et al., 1965; Casey et al., 1966). This led to a lively discussion. If these observations could be generalized so as to apply also to similar institutions in other countries, the question would be whether gonosomal aneuploidy had any bearing on the development of criminality and psychic diseases? In particular, the significance of a double Y condition as a predisposing factor was called in question. Unfortunately, from the outset the discussion became too categorical and oversimplified. When in subsequent studies socially well-adjusted individuals of normal intelligence were found, it was doubted whether aneuploidy had any importance at all. In a survey as recent as 1972, for example, Owen questions whether there is any connection at all between excess Y-chromosomes and behaviour disorders and mental diseases. Hook (1973), on the contrary, in a somewhat more detailed compilation, shows that there is a clear connection between the occurrence of double Y-chromosomes and individuals whom he defines as ‘mental-penal’. A common feature in all the literature, however, is that almost all writers insist on the importance of more research in this field.

Brave new world?

Recent developments in biology and medicine are raising new problems in the prevention and treatment of birth defects, and in research on these diseases. The problems include immediate issues such as genetic counseling, abortion for birth defects, the withholding of complex treatments from individuals in some situations, screening for genetic and other diseases, artificial insemination, and fertilization in vitro. Other problems, such as the dysgenic effects of modern medicine and the possibilities of cloning and gene therapy, are more remote. Each of these issues should be considered on its own merits and by its immediate and remote consequences rather than by a priori absolute criteria. Ways must be found to deal with these issues in a manner acceptable to most human beings. Open discussions and freedom from coercion are the best guarantees for ultimate success. The ethical human brain is the highest accomplishment of biologic evolution. By harmonizing our scientific, cultural, and ethical capabilities, the potentially achievable results can place us at the threshold of a new era of better health and less human suffering.