We found increased p-eEF2 IHC staining in hippocampal CA1 and CA2 (CA, cornu ammonis) fields in PD cases compared to controls, predominantly in neurons (Fig. 2a-b; additional controls shown in Additional file 1: Figure S5a-b; additional PD cases shown in Additional file 1: Figure S6a, panoramic views; Additional file 1: Figure S7a-b, magnified field views; quantitation of p-eEF2 IHC staining in areas CA1-CA2 is presented in Fig. 3a). This evidence concerns the gene EEF2 and Parkinson disease.