Functional genomics, fragile X syndrome, and RNA interference.

A remarkable revolution is occurring in biomedical science that is likely to have profound implications for the way we treat human diseases in the future. In the past 2 years, we have learned that introduction of short double-stranded RNA (dsRNA) molecules into vertebrate cells can silence any gene homologous to the dsRNA. This process is called RNA interference (RNAi) and is based on the ability of the cell to recognize and degrade messenger RNAs (mRNAs) that base-pair with the antisense component of the dsRNA. RNA interference probably arose as a defense against viruses and transposable elements that replicate by means of dsRNA intermediates. This form of genetic immunity is ancient; organisms from paramecium to humans use similar mechanisms. In addition, it is now evident that RNAi normally regulates some cellular genes, and a whole host of noncoding antisense mRNAs are produced in cells that function to regulate other genes. Herein we discuss the link between the RNAi machinery and fragile X syndrome and the application of RNAi to functional genomic analysis, and we speculate about the future applications of this technology to the therapy for human neurological disease.