Malocclusions in males with Klinefelter syndrome

'The incidence of the sex X chromosome Leads to phenotype differences of the body compared to the normal karyotype (46,XY). In the head region, the differences are biggest in the area of the craniofacial skeleton and the teeth. Based on a sample consisting of 32 males with Klinefelter syndrome (47,XXY) and a control group made of 70 males (46,XY) the authors established the incidence of orthodontic anomalies (malocclusions). Compared to the control group, the most present anomalies in the person having an extra X-chromosome were Anterior crowding and Class III malocclusion; following were Class II/2 and Posterior crossbite, as well as Diastema mediana. The authors have concluded that frequent malocclusion (62.5%) are the reduction of the bone structures of the craniofacial skeleton. This is a consequence of the direct impact of the X-chromosome on growth and development of the orofacial and craniofacial structures.