Clinical aspects of the fragile X syndrome.

Fragile X syndrome patients express a wide array of cognitive and other gender-specific phenotypic features. These manifestations result not only from molecular mechanisms that are altered as a result of the expansion of a CGG-repeat region in the FMR1 promoter, but also genetic factors such as founder effects and mosaicism. In this chapter, I will summarize the many and varied features of fragile X syndrome as they present themselves in a clinical setting and describe the procedures that are used to diagnose patients. Finally, I will briefly touch on recent developments that will affect patient screening in the future.