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We have established a ligation based typing method to detect HLA-B*27 alleles at the DNA level. The method requires amplification of exon 2 of the HLA-B locus from genomic DNA by the polymerase catalyzed chain reaction (PCR) using group specific primers. An aliquot of the PCR amplification product, heat stable ligase and a pair of oligonucleotide probes, designed to hybridize adjacently to HLA-B*27 specific sequences of the amplified DNA are subsequently thermocycled. If the probes are perfectly complementary they become ligated otherwise they stay separated. The ligation of probes can be detected through their different labels by an enzyme linked immunosorbent assay (ELISA). Ligation based detection of beta-actin sequences which have been co-amplified serves as positive control for each PCR reaction. We observed complete concordance when typing 76 HLA-B*27 positive and 107 HLA-B*27 negative individuals either by serology or by the ligation based approach. We conclude that ligation based typing is a reliable tool for the DNA based detection of HLA-B*27 alleles. The procedure allows automation to a large extent and should be easily applicable to the typing of other HLA-class I alleles.

In ten families with 65 children (with 64 informative meioses), a close linkage between the monocyte antigen locus (HMA) and HLA was found with a recombination frequency of 1.56%.

The frequency of HL-A antigens and genes WAS determined in a population of 600 unrelated Gernian people. The results confirmed the two loci concept for the HL-A system, and showed that the gene frequencies, the phenotype distributions and the haplotype frequencies are very similar to those observed in other Caucasian populations.