ApoE genotype in relation to AD and cholesterol A study of 2,326 Chinese adults

Objective: To calculate the frequencies of apolipoprotein E (apoE) alleles in a large Chinese community sample and to compare the serum cholesterol levels of e2, e3, and e4 carriers. Background: In comparison with Western populations, a lower frequency of the apoE e4 allele among the Chinese has been proposed as one factor for the lower prevalence of AD found in Chinese populations, but there are insufficient Chinese data on e4 frequency that are based on large community samples. In addition, although Western studies have repeatedly found a lower cholesterol level in e2 carriers and a higher cholesterol level in e4 carriers in comparison with e3 homozygotes, two Chinese studies have yielded inconsistent findings between them. Methods: During the incidence phase of an epidemiologic survey of several neurologic disorders in a Chinese community, the authors took blood samples from 2,326 participants to determine the apoE genotypes and to measure cholesterol levels. Results: The allelic frequencies of e2, e3, and e4 were 11.8%, 76.4%, and 11.8% among 17 AD patients, and 7.8%, 84.1%, and 8.1% for the entire sample. The mean cholesterol level of the e2 carriers was significantly lower, and that of the e4 carriers significantly higher, than that of the e3 homozygotes. Conclusions: The obtained e4 rate of 8.1% is lower than most of the Western findings, and this may account in part for the lower prevalence of AD found among the Chinese. The associations between the apoE genotype and serum cholesterol level are similar between Chinese and white populations.