Effects of X chromosome on size and shape of body: an anthropometric investigation in 47,XXY males.

The effects of an extra X chromosome on size and shape of body and head were studied in 47,XXY males; 25 anthropometric measurements were recorded from 29 adult 47,XXY males and compared with those of male relatives and control males. In stature, arm length, leg length, triceps skinfold, and subscapular skinfold 47,XXY males were larger and in biacromial diameter, bideltoid breadth, wrist breadth, and in most head dimensions smaller than normal males. Arm length was increased less than leg length. Increase in stature seemed to be caused solely by increased leg length, and the somewhat feminine proportions in trunk were caused by decrease in biacromial diameter. Correlations of the body and head dimensions between 47,XXY males and their male relatives were found to be normal. The present findings support the earlier proposals that X chromosome carries genes which influence linear growth. It is suggested that the reduction in biacromial diameter is caused by lowered plasma testosterone level which may also have affected sitting height. The control of body and head dimensions seems to be maintained relatively normal.