Our findings reveal a significant DAT deficit in the left and right structures of the caudate, putamen, and anterior putamen in subjects with PD compared to subjects with SWEDD(n=137) or HC(n=222), and that APOE ε2/ε4 may accelerate DAT deficits and brain alterations in both PD and SWEDD. The gene discussed is SLC6A3; the disease is Parkinson disease.