APOE and early-onset autosomal dominant Alzheimer disease: In contrast, patients with MCI show little hemispheric hippocampal asymmetry, while patients with type 2 diabetes or Alzheimer's disease exhibit the opposite pattern of asymmetry, particularly those with two (relative to one or zero) copies of the apolipoprotein E (ApoE) ɛ4 allele, a well‐established Alzheimer's risk genotype [16].