Human complementary component C'3: an appraisal.

Results obtained so far on the C3 polymorphism suggest that the system should be a valuable marker in population studies. The instability of the complement component C3 may, however, cause some practical problems in population genetic fieldwork, since a certain fraction of serum samples may be difficult to type with certainity due to storage alterations. Studies of the conversion rate and the concentration of C3 have shown that there is no significant difference between the phenotypes. And furthermore, the fact that there is good agreement with the Hardy-Weinberg distribution indicates that the conversion has had no appreciable selective effect on the phenotype distribution (Brönnestam et al., 1971).