Apolipoprotein E genotype and its pathological correlation in Chinese Alzheimer's disease with late onset

In this study, we attempted to find a relationship between apoliprotein E (ApoE) genotypes and Alzheimer's disease (AD) pathology in different areas of the brain in Chinese. We also studied the borderline group of possible AD (Poss). There were 34 definite or probable AD (Ad), 18 Poss, and 123 brains from age-matched normal subjects (N). ApoE genotype was determined by nested polymerase chain reaction on genomic DNA extracted from archival paraffin-embedded materials. Hippocampus (including entorhinal cortex), amygdala, superior temporal lobe, middle frontal gyrus, and inferior parietal lobule of the brains of Ad and Poss were examined with beta amyloid (A beta) immunostaining, and the same regions plus medial occipital lobe were examined with tau immunostaining. The percentage of plaque area stained for A beta in each brain region was obtained by an image analyzer, and the average number of neurofibrillary tangles stained for tau was counted with an eyepiece graticule. ApoE epsilon4 frequency was increased in both Ad (22.1%, chi2, df = 1, P = .00005), and Poss (33.3%, P = .000005) compared with N (5.3%). A beta load was significantly increased in the neocortex in Ad examined with at least 1 copy of epsilon4 compared with subjects without epsilon4 (Mann-Whitney, P = .014). The same trend, though not statistically significant, occurred in Poss (P = .15). Tau expression was associated with ApoE epsilon4 in neither Ad nor Poss. Poss is genetically and histologically similar to Ad, although the overall A beta load is significantly increased in the latter. These findings support the recent Consensus Report's findings that all Alzheimer-type pathology may be significant.