Genetic Polymorphism of the Fourth Component of Complement (C4) in the Pig

Using agarose gel electrophoresis and immunoblotting with rabbit anti-human C4, a genetic polymorphism was found in the fourth component of complement (C4) in 258 pigs of 6 breeds (Landrace, Large White, Duroc, Berkshire, Meishan and Jinhua) . Nine phenotypes were observed. Family data indicated that pig C4 phenotypes were inherited under control of four codominant alleles named C4A, C4B, C4C, and C4D at a single autosomal locus. Marked differences in gene frequencies at the C4 locus were observed among breeds, that is, the C4A frequency was higher in Meishan and Jinhua than in other European breeds; C4D frequency was higher in European breeds; C4B was rare in all breeds except in the Berkshire and C4C geney was observed in all breeds. No variant in pig plasma factor B was observed in all the breeds studied.