Mice homozygous for the human apolipoprotein E4 (ApoE4) variant, which is the greatest genetic risk factor for AD in people, showed an age-dependent decrease in exosomes associated with reduced levels of TSG101 and RAB35 [68], both of which are involved in exosome biosynthesis and release [25,69]. The gene discussed is TSG101; the disease is Alzheimer disease.