Polymorphism of C3 component of complement in the Polish population. II. Rare phenotypes in C3 system.

In a sample of the Polish population including 4741 adults, 15 phenotype variants were found in 22 of them. These variants are determined by 12 rare alleles of the mean frequency 0.0023. Family studies of several probands with C3 phenotype variants have confirmed their genetic determination. They have been observed to be heterozygotes in which beside one common gene, rare codominant alleles are situated. Studies on polymorphism of C3 component carried out on numerous populations, allowed the discovery of new phenotype variants within the C3 group system. Family studies have confirmed their hereditary character and that they are determined by the alleles codominant in relation to the commonly occurring C3S and C3F. The paper presents the results of studies on the rare C3 phenotype variants encountered in the Polish population.