Fragile X Syndrome

Fragile X syndrome (FXS) represents the most common form of inherited mental retardation, and is associated with a highly variable cognitive and behavioral phenotype as well as a characteristic profile of physical features. FXS is caused by a trinucleotide repeat expansion in the FMR1 gene, leadind to transcriptional silencing of the gene. Typically, no functional FMR1 mRNA is produced, and the fragile X mental retardation protein (FMRP) is also absent. In the past decade, significant research advances have been made toward delineating the role of FMRP in normal brain function and the effects of its absence on neuroanatomy and physiology.