Genetic polymorphism of human C1R subcomponent of the first complement component in the Japanese population.

Genetic polymorphism of the C1R subcomponent of human complement component C1 has been investigated in neuraminidase treated EDTA plasma samples of 440 healthy Japanese individuals living in Tokyo by means of thin-layer polyacrylamide gel isoelectric focusing (PAGIEF) at pH 3.5-9.5 in the presence of 8.0 M urea followed by an electroblotting with enzyme immunoassay. Three common and three rare alleles were detected in the Japanese population. Of these, two common alleles were identical to C1R1 and C1R2 and other new alleles were tentatively designated C1R3, C1R4, C1R5 and C1R6, respectively. The results of the family studies suggested that the genetic model for C1R polymorphism assumed autosomal codominant Mendelian inheritance. The allele frequencies were estimated as C1R1 = 0.4216, C1R2 = 0.3602, C1R3 = 0.2068, C1R4 = 0.0091 and C1RR(C1R5 and C1R*6) = 0.0023, respectively. The distribution of allotypes fitted the Hardy-Weinberg equilibrium. The C1R system provides a useful genetic marker for human genetics, anthropologic studies and forensic science.