Long CGG‐repeat tracts are toxic to human cells: Implications for carriers of Fragile X premutation alleles

People with 59-200 CGG AE CCG-repeats in the 5 0 UTR of one of their FMR1 genes are at risk for Fragile X tre- mor and ataxia syndrome. Females are also at risk for prema- ture ovarian failure. These symptoms are thought to be due to the presence of the repeats at the DNA and/or RNA level. We show here that long transcribed but untranslated CGG-repeat tracts are toxic to human cells and alter the expression of a wide variety of different genes including caspase-8, CYFIP, Neuroten- sin and UBE3A. 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.