Frequency distributions of plasma apolipoprotein (a) levels and phenotypes: A comparison between southern and northern Chinese populations

Abstract

Objective This study was designed to examine the genetic variation and levels of apolipoprotein (a) [apo(a)] in Chinese living in two different geographical regions of China and the influence of the apo(a) size polymorphism on plasma apo(a) levels. Methods An immunoradiometric assay was used to determine plasma apo(a) levels and a simplified and sensitive SDS-agarose gel electrophoresis method followed by immunoblotting with chemiluminescent detection for apo(a) phenotyping was employed to compare the frequency distributions of apo(a) levels and phenotypes in southern (Hong Kong) and northern (Henan) Chinese populations. Results Distributions of plasma apo(a) levels were highly skewed in both population groups- Although plasma apo(a) levels were generally higher in northern Chinese than in southern Chinese this was not explained by differences in K-IV repeats allele frequencies between these two population groups. The association of K-IV repeat length with apo(a) levels is similar in the two populations. Conclusions We conclude that besides the apo(a) size polymorphism, which is similar in these two Chinese populations, other factors affect apo(a) levels to a certain degree. Most likely, this is the sequence variation in apo(a) gene which may not be the same in different Chinese populations.