Identification of Apo(a) Phenotypes in a Korean Population Using a Standardized Nomenclature System Based on the Number of Kringle IV Repeats

We determined serum lipoprotein(a) [Lp(a)] concentrations and apolipoprotein(a) [apo(a)] phenotypes in 193 healthy Koreans. We analysed the apo(a) phenotypes by a simplified sodium dodecyl sulphate-polyacrylamide gel electrophoresis method and classified apo(a) isoforms objectively using an apo(a) phenotype standard with a known number of kringle IV repeats. The frequency distribution of Lp(a) levels showed marked positive skew with a mean of 0·143 g/L and a median of 0·052 g/L. Of the 193 subjects tested, no bands were detected in three, and single- and double-band phenotypes were observed in 103 and 87, respectively. Among the Koreans, the most frequent phenotype was S5(39·4%), followed by S4S5(17·1%), S5S5(14·0%), S4(11·4%), S3S5(5·2%), and the remaining phenotypes (13·0%). The calculated apo(a) allele frequencies were LpF, 0·003; LpS1, 0·013; LpS2, 0·010; LpS3 0·048; LpS4 0·198; LpS5, 0·563 and Lp0, 0·165. We found that the serum Lp(a) concentration in Koreans was similar to that of Caucasians, but the apo(a) allele size distribution was shifted toward higher molecular weights.