Alternative splicing of FMR1 gene in fetal and adult human brain

Fragile X syndrome can be caused by lack of expression of the FMR1 gene, wh ich encodes an RNA binding protein. Extensive alternative splicing of the F MR1 gene has been observed in human and mice. Five regions of the FMR1 gene have been reported to be alternatively spliced. To determine whether such alternative splicing might be developmentally regulated, RT-PCR was used to analyze poly(A) RNA transcripts of the FMR1 gene in adult and fetal human brain. A new alternative acceptor site in exon 17 that may lead to a trunca tion of the last 53 amino acids of the FMR1 protein was described. This acc eptor site was used in several regions of fetal brain but not in adult cort ex. The results suggest that alternative splicing of the FMR1 gene may be s ubject to developmental switching.