Fragile X (Martin-Bell) syndrome.

Fragile X syndrome is a common condition resulting from a cytogenetic abnormality in the X chromosome. Mental retardation, characteristic facies, and large testes are some of the most important characteristics of the condition. The relatively high incidence of the syndrome--approximately one per thousand--the high incidence of cardiac anomalies in these individuals, the oral and facial features associated with the condition, and the paucity of reported cases in the dental literature make it particularly interesting to dentistry. Here we report the case of a 12-year-old male, including the cytogenetic and cephalometric analyses, presenting with some of the classic features and some features not commonly reported.