Background: Fragile X syndrome is caused by loss of function of the fragile X mental retardation 1 (FMR1) gene and shares multiple phenotypes with autism. We have previously found reduced expression of the protein product of FMR1 (FMRP) in vermis of adults with autism. Methods. In the current study, we have investigated levels of FMRP in the superior frontal cortex of people with autism and matched controls using Western blot analysis. Because FMRP regulates the translation of multiple genes, we also measured protein levels for downstream molecules metabotropic glutamate receptor 5 (mGluR5) and -aminobutyric acid (GABA) A receptor 3 (GABR3), as well as glial fibrillary acidic protein (GFAP). Results: We observed significantly reduced levels of protein for FMRP in adults with autism, significantly increased levels of protein for mGluR5 in children with autism and significantly increased levels of GFAP in adults and children with autism. We found no change in expression of GABR3. Our results for FMRP, mGluR5 and GFAP confirm our previous work in the cerebellar vermis of people with autism. Conclusion: These changes may be responsible for cognitive deficits and seizure disorder in people with autism.