Fragile-X syndrome: genetic aspects and stomatologic evaluations

The fragile-X syndrome is the most common cause of inherited mental retardation and it is associated with the FMR1 gene on X chromosome. The origin of anatomic anomalies of maxillo-facial complex is still discussed in literature. The authors describe the syndrome and report a clinical case. Genetical and clinical aspects and the incidence of caries, periodontal disease and occlusal abrasion are reviewed. Occlusal conditions, particularly openbite and crossbite, are considered. The incidence of fragile-X syndrome is 1: 2000 in males and 1:4000 in females, despite this the syndrome is diagnosed with a lot of difficulties yet, because of extreme variability of the phenomenological aspects. Patients often show severe mental retardation, linked to a peculiar profile of cognitive, behavioural, and emotional dysfunction and to distinctive anatomic features, which become more evident after puberty. Concerning oral characteristics, it doesn't seem to be a significant association between the syndrome and the incidence of caries or periodontal diseases, while an ogival shaped palate is peculiar. Literature review suggests that when male patients with severe mental retardation without well-known cause are visited, the ipothesis of X-fragile syndrome should be considered. Even though the diagnostic hypothesis may arise from the observation of typical somatic features, the diagnosis can be confirmed only by genetical tests.