Development and clinical evaluation of a microarray for HLA-A and -DRB1 genotyping

Microarray technology makes high-throughput genotyping possible by permitting the simultaneous analysis of large sets of genes on a small reaction slide. Human leukocyte antigen (HLA) loci showing high polymorphisms are suitable targets for microarray. In this study, we developed a microarray kit with newly designed oligonucleotide probes for the genotyping of HLA-A and -DRB1. In total, 42 probes were designed to hybridize to polymorphic sites for HLA-A and 36 for HLA-DRB1. Asymmetric polymerase chain reaction (PCR) using four primers was performed to amplify exon 2 of HLA-DRB1, whereas symmetric PCR was performed to amplify both exons 2 and 3 of HLA-A. Evaluation of performance using samples from 138 Koreans disclosed consistent microarray results with all sequence-based typing at the low-resolution level. Despite the occurrence of ambiguities in 35 HLA-A (25.4%) and 5 HLA-DRB1 (3.6%) cases, correct genotypes were assigned with high certainty by referring to allele distribution in Koreans. These data clearly indicate that our newly developed microarray kit is optimal in determining correct genotypes at the low-resolution level in Koreans.