We reviewed the literature on sex differences in genetically determined Alzheimer’s disease (AD), focusing on autosomal dominant AD (ADAD), Down syndrome-associated AD (DSAD), and APOE4 homozygosity, particularly regarding disease penetrance, symptom onset and clinical progression, and trajectories for markers of amyloidosis (A), tau pathology (T) and neurodegeneration (N). Here, APOE is linked to Alzheimer disease.