Effects of the Y chromosome on quantitative growth: an anthropometric study of 47,XYY males.

The aim of the study was to investigate the effects of the Y chromosome on different body and head dimensions of 47,XYY males, and especially its effect on their body proportions. From seven adult 47,XYY males 25 anthropometric measurements were recorded and compared with four male relatives and 42 control males. In most dimensions 47,XYY males were larger than the normal males, the difference being mainly between 0.5 and 1.5 S.D. units. The body proportions of 47,XYY males were found to be similar to those of the normal males when the effect of size was allowed for. It is concluded that the extra Y chromosome in 47,XYY males causes an increase in their growth without affecting the body proportions. This finding suggests that the Y chromosome contains gene(s) which affects growth by increasing its quantitative outcome. This effect may be mediated by a direct action of the Y chromosome on the cells. It also may seem that the Y chromosomal gene(s) influence the development of the sex difference in height and body size.