Distribution of complement factors Bf, C2 and C6 in the Western Pacific.

Complement components Bf, C2 and C6 have been typed in various Micronesian, Polynesian, Melanesian and Indian populations of the Western Pacific. BfS and BfF gene frequencies are heterogeneous throughout the region but the number of alleles in the Bf system is restricted. C2 is also restricted with the C22 gene frequency from 0-1.3% in all groups except Fijian Indians where it is 4.8%. The C6A and C6B frequencies of Polynesians, Melanesians and Fijian Indians are within the narrow range of frequencies reported for these alleles from other parts of the world. In the Micronesians of Nauru, a third polymorphic allele (C6Nauru) occurs together with a number of rare alleles (C6R). The Nauruan C6 gene frequencies are C6A 44.6%, C6B 45.2%, C6Nauru 6.7% and C6R 3.5% C6Nauri is present in low frequencies in most other Western Pacific populations and C6R variants occur in Polynesians.