The ITI system in South Koreans and Iranians analysed by an improved classification procedure. Distribution of alleles and description of "new" phenotypes.

Phenotype and gene frequency distributions of the inter-alpha-trypsin inhibitor (ITI) system were analysed in populations from southern Korea and from Iran. The gene frequencies of the common alleles ITII and ITI2 were 0.532 and 0.422, respectively, in southern Korea, and 0.612 and 0.354, respectively, in Iran. The postulated third allele, ITI3, was found in the homozygous form. Gene frequencies of this rare allele were calculated to be 0.042 and 0.029 in Korea and Iran, respectively. Two additional rare alleles, ITI4 and ITI5, determine further phenotypes found in the population from Taejon (Korea) and Iran, respectively, in combination with the common ITI2 allele. Gene frequencies of ITI4 and ITI5 were calculated to be 0.006 and 0.005, respectively. For phenotype classification, untreated sera were separated by isoelectric focusing (IEF) on polyacrylamide gels followed by immunoblotting.