APOE and early-onset autosomal dominant Alzheimer disease: Of the 45 enrolled MCI patients (24 female), the score of mini mental state examination (MMSE), clinical dementia rating-sum of boxes, and Alzheimer’s disease assessment scale-cognition 12 (ADAS-Cog 12) were 27.64 (1.88), 0.95 (0.78), and 8.68 (3.66), respectively [mean (SD)], with 33.33% APOE4 positive.