HETEROGENEITY OF THE HUMAN H-BLOOD-GROUP ALPHA(1,2)FUCOSYLTRANSFERASEGENE AMONG PARA-BOMBAY INDIVIDUALS

Background and objectives: The para-Bombay phenotype has a relatively high frequency of about 1 in 8,000 Taiwanese. Studies were carried out on eight healthy and unrelated Taiwanese with the para-Bombay phenoty pe to cast light on its immunogenetic basis. Materials and methods: Bl ood and saliva samples were tested with standard hemagglutination tech niques. Salivary ABH substances were determined by hemagglutination in hibition. PCR techniques were used to amplify the coding region of the H genes. Results: Five different h alleles, designated as h1, h2, h3, h4 and h5, were identified in the Taiwanese with the para-Bombay phen otype. The h1 allele loses one of the three AG repeats located at the nucleotides 547-552 of the H gene, whereas two of the three T repeats located at the nucleotides 880-882 are deleted in the h2 allele. The h 3 allele contains a C-658 to T missense mutation, whereas two missense mutations, C-35 to T and A(980) to C were identified in the h4 allele . A T-460 to C missense is present in the h5 allele. The h5 allele was identified in an individual whose red blood cells contain blood group A antigen but not H antigen, and thus may be considered a weak varian t of the H gene. Conclusions: So far no biologic relevance of the H an tigen has been discovered, and its deficiency does not seem to produce any deleterious effects. There may be better understanding of the evo lutionary basis for the polymorphisms at these loci after systematic s tudy of different ethnic populations.