(UTR) of the first exon of the FMR1 gene in humans results in fragile X syndrome. Long
stretches of CGG repeats that are known to be highly unstable in humans have so far failed
to show similar intergenerational instability in transgenic mice. We generated transgenic
lines that show a dramatic increase from 26 to> 300 repeats in three generations. One of the
salient features of our transgene is the inclusion of the origin of replication of simian virus-40 …