Allotypes of the fourth component of complement in Koreans.

The analysis of genetic polymorphism in C4 was performed on EDTA-plasma from 169 healthy unrelated Koreans. Plasma samples were subjected to high-voltage agarose gel electrophoresis followed by immunofixation. C4B allotypes were further detected by a hemolytic overlay method. The allele frequencies of C4A and C4B were as follows; for C4A, C4A3 = 0.6099, C4A4 = 0.1702, C4AQ0 = 0.1525, C4A2 = 0.0461, and C4AR = 0.0213; for C4B, C4B1 = 0.6406, C4B2 = 0.2740, C4B5 = 0.0569, C4BQ0 = 0.0178, and C4BR = 0.0107. C4A3 and C4B1 were among the most common alleles at each locus. C4A6 was not detected in this study, but this allele is relatively common in both Caucasoid and Negroid populations. C4B5 is a common allele in Asian, which is rare in Caucasoids and Negroids. C4B*5 appeared to be a characteristic allele of Oriental. In the C4A locus, five individuals with duplicated allotypes (three C4A 3,3 + 2, one C4A 4,3 + 2, and one C4A 3,3 + 3) were observed, and in the C4B locus, one individual with duplicated allotype (C4B 1,1 + 1) was detected.