Interestingly, T-tau and P-tau concentrations were notably increased in APOE ε4 carriers compared to APOE ε4 non-carriers in MCI, but there was no significant difference in the concentrations of T-tau and P-tau between APOE ε4 carriers and APOE ε4 non-carriers in CN and AD. The gene discussed is MAPT; the disease is Alzheimer disease.