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 ITI*1, ITI*2, ITI*3 and ITI*4 were calculated to be 0.564, 0.083, 0.337 and 0.004, respectively. One unknown rare allele, ITI*6, determines further phenotypes in combination with the alleles ITI*1 and ITI*3. Gene frequency of ITI*6 was calculated to be 0.012. The common alleles are represented by ITI*1 and ITI*3. The allele distribution is therefore different from European and Asian populations.