XYY Complement

The incidence of males with an XYY chromosome complement in a maximum security hospital was found to be 3% (Jacobs et al., 1965). These males were exceptionally tall, and it was found that 1 in 3 of the men of over 6 ft. (183 cm.) in this hospital had an XYY chromosome constitution. This very high incidence in an over-6 ft. group was confirmed in a special hospital for the subnormal (Casey et al., 1966). Apart from their tall stature no other abnormality has been detected in these XYY males. The behavioural disorders and pattern of the crime among these XYY males has been extensively investigated (Price and Whatmore 1967a, b). From these studies it was suggested that the extra 'Y' chromosome was a factor contributing to their disorder of personality and their early conflict with the law. It was thought of some interest to know if the presence of an additional 'Y' chromosome had any influence on the secretion of the male sex hormone, testosterone. In the present study, urinary testosterone excretion rates have been measured in two groups of males with an XY constitution and a third group of males with an XYY constitution.