An extra X chromosome effect on craniofacial morphogenesis in men.

A comparative study of the craniofacial complex in men with an extra X chromosome, and normal male and female individuals was carried out using cephalometric radiography. The anterior cranial base, anterior and posterior facial height, maxillary base and ascending ramus were found to be significantly decreased in men with Klinefelter syndrome when compared to the male control group. Significant differences in the lengths of mandibular base and posterior cranial base were not found. When compared to the female control, all structures examined were significantly increased, except for the maxillary base.