Inter-alpha-trypsin inhibitor polymorphism. An improved phenotyping procedure and two new alleles.

Serum samples treated with chondroitinase ABC and sialidase were investigated for the detection of inter-alpha-trypsin inhibitor (ITI) polymorphism. The improved phenotyping procedure has proved to be the most practical method for ITI phenotyping. The ITI allele frequencies were examined in 2 population samples from Japanese (n = 365) and Thais (n = 150). Three common alleles, ITI1, ITI2, and ITI3 were identified in both populations, but the Thai population showed a higher frequency of ITI1 and a lower frequency of ITI3. Two new alleles were found, which were tentatively denoted ITIY and ITIT. The ITIT allele frequency in Thais was 0.047.