Inter-alpha-trypsin inhibitor polymorphism in African blacks.

The inter-alpha-trypsin inhibitor (ITI) polymorphism was analyzed in an African Negroid population using polyacrylamide gel isoelectric focusing and subsequent immunoblotting. Gene frequencies of ITI1, ITI2, ITI3 and ITI4 were calculated to be 0.564, 0.083, 0.337 and 0.004, respectively. One unknown rare allele, ITI6, determines further phenotypes in combination with the alleles ITI1 and ITI3. Gene frequency of ITI6 was calculated to be 0.012. The common alleles are represented by ITI1 and ITI3. The allele distribution is therefore different from European and Asian populations.