Does the geographical gradient of ApoE4 allele exist in China? A systemic comparison among multiple Chinese populations

Abstract

The allelic frequencies of apolipoprotein E (apoE) vary substantially around the world. There is a conspicuous south-to-north gradient of e4 frequencies in Europe, with the proportion of e4 carriers from only 10-15% in the south to 40-50% in the north. The mechanism may be related to the possibility that e4 carriers are less likely to develop vitamin D deficiency. In addition, Asian populations traditionally have lower e4 frequency than Europeans, which may be attributed in part to the scarce or irregular food supplies in Western world in the recent past. However, whether these geographical distribution gradients exist in China is yet unknown. ApoE genotypes of 200 children from Nanning City were determined by PCR-restriction fragment length polymorphism (RFLP) analysis. Allele frequency data of 18 other populations were collected from published sources and correlated with latitude and longitude information from different geographic resources. In our subjects, the frequencies of apoE genotypes were E3/E3: 73.0%, E3/E2: 15.0%, E4/E3: 5.0%, E4/E4: 5.0%, and E4/E2: 2.0%; the frequencies of apoE alleles were e2: 8.5%, e3: 83.0%, and e4: 8.5%, respectively. The total sample consisted of 3,679 individuals from 19 Chinese populations; the allelic frequencies were e2: 7.6%, e3: 85.5%, and e4: 6.9%, respectively; the proportion of e4 carriers was from 4.9% in Kunming to 17.5% in Harbin. Systemic comparison among multiple Chinese populations revealed that positive correlation existed between the e4 allele frequency distribution and latitude north (r=0.586, P=0.008), but no correlation of the e4 allele frequency distribution with longitude east was found (r=-0.018, P=0.942). We conclude that there is a south-to-north, but not an east-to-west gradient for the apoE4 allele in China.

The Shanghai Aging Study: Study Design, Baseline Characteristics, and Prevalence of Dementia

“…However, there is great ethnic variation in APOE frequencies. The frequency of the APOE-ε4 allele in our population is 9.3%, which is in the range of that in Asian (including Chinese) populations (6.3-9.3%) [42,43,44], but lower than that in Caucasian and African American populations (11-27%) [45]. Multivariate analyses did not explore the presence of APOE-ε4 as an independent risk factor of dementia.…”

Apolipoprotein E genotyping using PCR-GoldMag lateral flow assay and its clinical applications

“…All genotyping results (100%) were in accordance with the results of direct DNA sequencing. In the subjects (n=305), the overall allele distribution was similar to a previous study (34), with no significant difference in allele distribution (Chi-squared test, P=0.598). These results indicate the reliability of using the PCR-GoldMag LFA method for ApoE genotyping.…”

Geographic and Sex Difference in the Distribution of Intracranial Atherosclerosis in China

“…17 Genetic polymorphism is another influential factor for these differences. Hu et al 18 found that positive correlation existed between the e4 allele frequency distribution and a northern latitude (r=0.586; P=0.008) in China. Many studies have shown that ICAS is associated with lipid disorder, 19 hypercholesterolemia, 20 tobacco use, 21,22 and diabetes mellitus.…”