[Application value of allele frequencies in direct identification of ambiguous HLA genotypes]

This study was aimed to investigate the application value of allele frequencies in direct identification of the ambiguous HLA genotypes. The HLA-A, HLA-B and HLADRB1 loci in 658 Chinese Han donor were detected by PCR-SBT method, the ambiguous genotyping samples were identified by using high resolution PCR-SSP and heterozygous ambiguity resolution primers (HAPRs) methods. The relative probability of true genotypes was calculated by using allele frequencies and was compared with true results. The results indicated that the relative probability of true genotype > 95% in 220 HLA-A ambiguous samples, 238 HLA-B ambiguous samples and 107 HLA-DRB1 ambiguous samples were 99.5% (221/222), 95.8% (228/238) and 97.7% (104/107) respectively. As compared with phenotyping results detected by PCR-SSP and HARP methods, the matching ratios for HLA-A, HLA-B and HLA-DRB1 loci were 100% (222/222), 99.6% (237/238) and 99.1% (106/107) respectively, while the mismatch genotypes were observed only in B*3501/5501 and DRB1*1241/1504, the relative probability of them were 40.3% and 2.1% respectively. It is concluded that the detection method using allele frequencies to directly identify the ambiguous HLA genotypes in large scale PCR-SBT genotyping of donors not only can give higher accurate and reliable results, but also is a simple, rapid and cost-saving method. This method has to be used with great care in the identify-test of patient-donor pair before the transplantation.