Cephalometric analysis of pharyngeal airway space dimensions in Turner syndrome.

Turner syndrome (TS) that is due to a total or partial lack of an X chromosome affects about 1 in 2000 girls. The syndrome is characterized by short stature and gonadal dysgenesis. Its documented craniofacial features include retrognathic jaws, a short mandible, and a large cranial base angle. Our aim was to find out whether the syndrome also has an effect on the pharyngeal airway space. We retrospectively analysed lateral cephalograms of 35 TS subjects whose age ranged from 6.5 to 21 years and of 35 healthy female controls matched for age. On those, we did 7 linear and 10 angular cephalometric measurements and 9 pharyngeal measurements. Differences between the subjects with TS and their controls were assessed by paired two-tailed T-test. In the girls with TS, both the maxilla and the mandible were more retrognathic (SNA, P = 0.015 and SNB, P < 0.001), the mandible was shorter (TM-Pgn, P = 0.016), and the cranial base angle was larger (SNBa, P = 0.025) than in the controls, confirming the results of earlier studies. Notably, all six pharyngeal airway measurements were smaller in girls with TS. Two of them, PNS-ad2 and PAS, were statistically significantly smaller (P = 0.019 and P = 0.012, respectively). Thus, a narrow pharynx, either as a primary finding or as a consequence of the maxillo-mandibular retrognathism, further delineates the phenotype. This may imply an elevated risk of sleep apnoea in females with TS.

Premolar hypodontia is a common feature in Sotos syndrome with a mutation in the NSD1 gene.

The major diagnostic manifestations in Sotos syndrome include frontal bossing, downward slanting palpebral fissures, a prominent jaw, learning disability, and childhood overgrowth. Over 90% of clinically diagnosed patients have an abnormality in the NSD1 gene. We investigated the dental manifestations of this disorder and found one or several premolar teeth were absent in 9 out of 13 (69%) affected children and adolescents. A heterozygous mutation in the NSD1 gene was identified in 12 patients, including all patients with hypodontia. The severity of the hypodontia seemed to increase with the severity of aberration of the NSD1. More than 50% of the patients had enamel defects or excessive tooth wear. Dental age, based on tooth formation, was within the normal range. A characteristic occlusion for Sotos syndrome could not be identified. As agenesis of premolars was a common feature in these patients affected with Sotos syndrome, we recommend panoramic radiography at the age of 7 years. If premolars are missing, proper preventive and restorative care is necessary to maintain the deciduous molars.