Prior studies among both AD (APOE ε 4/4 carriers, n = 34) and DLB (APOE ε 4/4 carriers, n = 7) patients noted that smaller hippocampal volumes on MRI were noted with an increasing burden of APOE ε4 dosage [43], similar to that seen for cognitively normal middle-aged subjects [44]. The gene discussed is APOE; the disease is Alzheimer disease.