APP and Lewy body dementia: Consistent with an association of RAB39B dysfunction with Aβ and aSyn pathology in DLB cases, the levels of p‐aSyn as determined via pSer129‐aSyn antibody (P < 0.001; Figure 4C i) and Aβ via the non‐APP cross reacting Aβ antibody MOAB‐2 (P < 0.01; Figure 4C ii), were increased in DLB cases compared to controls, within crude temporal cortex lysates.