APOE and Alzheimer disease: Altogether, these results suggest that the distribution of α-SYN shifted from soluble to insoluble fractions in AD cases, in particular, AD brains with LB pathology; and that APOE4 gene did not significantly affect the amount of insoluble α-SYN, although it was associated with less detergent-soluble α-SYN in AD + LB brains.