Duchenne muscular dystrophy is associated with mental retardation and several dystrophin transcripts are differentially expressed in specific brain areas. G-dystrophin (Dp71) is known to be the predominant isoform in the brain. We have localized its mRNA to be present predominantly in the dentate gyrus and in the olfactory bulb. This distribution is specific and significantly different from that for the full-size dystrophin transcripts, present mainly in CA regions of the hippocampus, in the cerebral cortex and in cerebellar Purkinje cells. Furthermore, our data show that the various dystrophins co-localize with the dystroglycan in the brain.