Validation of DNA-based HLA-A and HLA-B testing of volunteers for a bone marrow registry through parallel testing with serology

A total of 42,160 individuals were typed for HLA-A and HLAB by both serolog y and PCR-based typing. The HLA assignments included all of the known serol ogical equivalents. The majority of the individuals (99.9%) were from U.S. minority population groups. The serologic typing was performed between 1993 and 1997 at the time of recruitment for the National Bone Marrow Program ( NMDP) registry. The polymerase chain reaction (PCR)-based typing was carrie d out in two phases. In phase I, DNA typing was performed by PCR using sequ ence-specific oligonucleotide probes (PCR-SSOP) or PCR using sequence-speci fic primers (PCR-SSP) without knowledge of the serologic assignments. Discr epancies were identified between the serologic and DNA assignments in 24% o f the volunteers (8% of volunteers differed for only HLA-A assignments, 13% for HLA-B, and 3% for both HLA-A and -B) and a potential explanation was a ssigned each discrepant serology/DNA pair. In phase II, a random sampling s cheme was used to select a statistically significant number of individuals for repeat DNA typing from each of these categories. The categories include d antigens missed by serology, nonexpressed (null) alleles, PCR amplificati on failures, misassignment of antigens and nomenclature issues. Only a sing le individual was found to carry a null allele. DNA-based testing correctly typed nearly 99% of the donors at HLA-A, more than 98% at HLA-B, and more than 97% at both HLA-A and -B validating this methodology for registry typi ng.