A combined study of human complement C7 IEF and C7 M/N polymorphisms in the Chinese Han population.

Two polymorphisms of human complement C7 (IEF and M/N) have been studied in the Han population from Chengdu, People's Republic of China. One was determined by polyacrylamide gel isoelectric focusing (IEF) of neuraminidase-treated EDTA plasma, whereas the other was performed by a combination of two ELISAs using a C7-allospecific monoclonal antibody or polyclonal C7-specific IgG as coating antibodies. In 121 Chinese subjects IEF patterns of C7 were classified into three common and four rare phenotypes. The C7 IEF allele frequency estimates for C71, C72, C73, C74 and C77 were 0.831, 0.095, 0.045, 0.025 and 0.004, respectively. The C7 M/N typing in 113 Chinese individuals revealed the following allele frequencies: C7M = 0.805, C7*N = 0.195. Allelic associations between C7 IEF alleles and the C7 M/N alleles are also discussed.