Notably, the presence of APOE ε2/ε2 dramatically increased the risks of both PSP (3.7% vs. 0.3%, OR: 9.56, P = 0.010) and CBD (5.9% vs. 0.3%, OR: 21.40, P = 0.018) in this subgroup of 109 PSP patients, 17 CBD patients, and 599 controls. The gene discussed is APOE; the disease is red-green color blindness.