However, we observed higher levels of all CD200R1 mRNAs in the hippocampus of PD patients at advanced LP stages (LP 5 and LP 6) than at early LP stages (LP 4 and LP 4-5) (Fig. 6a, b); this effect was not observed at the protein level, which already showed a significant increase at LP 4 and LP 4-5 stage (Fig. 6c). This evidence concerns the gene CD200R1 and Parkinson disease.