Abstract: Objective To study the molecular genetic background of Diego blood group in Chinese Han population.Methods A total of 2 990 blood samples from unrelated blood donors were phenotyped for Dia and Dib by serological method.Twenty randomly selected samples of Di(a-b+) type and all of the samples of rare Di(a+b-) phenotype by screening were genotyped by PCR-SSP and direct DNA Sequencing.Results Of the 2 990 samples identified by serological method,2 821 were Di(a-b+),167 were Di(a+b+) and 2 were Di(a+b-).All of the 20 randomly-selected samples with Di(a-b+) phenotype were DI2DI2 homozygote by PCR-SSP genotyping,with nucleotide C at nt position 2 561 in exon 19 by direct sequencing of the DI gene.The 2 samples of rare Di(a+b-) phenotype were both the DI1DI1 homozygote,with nucleotide T at nt position 2561 in exon 19.Conclusion Our results indicate that the expression of Dia and Dib antigens in Chinese Han population most likely result from a single nucleotide T to C substitution at nucleotide position 2561 in exon 19 of the DI gene,which subsequently leads to an amino acid 854 change from Pro to Leu.

Key words: Chinese Han population, Diego blood group, PCR-SSP, direct sequencing