title: Polymorphism of the second component of human complement (C2). Observation of the rare phenotype (C2 2 (= C2 B) and data on the localization of the C2 locus in the HLA region.
abstract: The polymorphism of the second component of human complement was studied by means of isoelectric focusing in polyacrylamide gels with subsequent complement-dependent lysis of sensitized sheep erythrocytes in an agarose overlay containing C2-deficient or normal human serum. In a material of 289 unrelated individuals the following gene frequencies were observed: C21=0.965 and C22=0.035. The rare phenotype C2 2 (=C2 B) could be seen once in a child of a C2 1--2 heterozygous mother. The investigation of the C2/HLA relationship revealed a very close linkage: Among 62 informative meiotic divisions one recombination between HLA-B and C2 was found (i.e. 1.61%); in addition, C2(2) was significantly associated with HLA-B15 and -Cw3. In a family with an HLA-B/D(DR) crossover C2 segregated together with HLA-D(DR). This supports the assumption of a C2 structural locus outside HLA-B, probably near HLA-D(DR).
mesh_terms: D000483:Alleles; D002874:Chromosome Mapping; D003175:Complement C2 / Q000235:genetics*; D008040:Genetic Linkage; D006680:HLA Antigens / Q000235:genetics*; D006238:Haploidy; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D010641:Phenotype; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic
chemical_list: D003175:Complement C2; D006680:HLA Antigens