[Progress of DNA based HLA typing methods]

HLA genes exhibit high degrees of polymorphism, and a total of about 400 alleles have been identified at HLA-A, B, C and DR loci up to now. A number of DNA-based typing methods using specific primers, specific probes or restriction enzymes have been developed. In HLA class II allele typing, a few methods which are simple in handling and able to determine the alleles automatically, have been available. We have recently developed PCR MPH (microtiter plate hybridization) method, and this method has been in use for routine typing of DRBI alleles. In HLA class I typing, however, DNA typing system suitable for routine typing laboratories has not been established yet, because the polymorphism spreads two exons intervened by an intron. Nevertheless, allele typing of some antigen groups such as A2 and B61 groups have been established using PCR MPH method.