Although a decrease in synaptic proteins such as synapsin, SNAP-25 and synaptophysin has been demonstrated in post mortem CJD cerebral cortex and cerebellum [10,23,24] and in the RML mouse model [25], these analyses were undertaken at a time when there was extensive neuronal death and thus severe synaptic loss would be expected. This evidence concerns the gene SYP and Creutzfeldt Jacob disease.