Evidence that HLA-B*2706 is not protective against spondyloarthropathy.

Objective. Studies in Southeast Asia showed that HLA-B * 2704 is positively associated with spondyloarthropathy (SpA), while B * 2706 does not occur in such patients. In view of the absence of an association between B * 2706 and SpA it was suggested that B * 2706 protects against the disease, while it is supposed that B * 2704 presents pathogenetic peptides. We studied families in which both B * 2704 and B * 2706 occurred to see whether in B * 2704/B * 2706 heterozygotes the effect of one of the subtypes shows a preponderance over the other. Methods. Two families of mixed Chinese/Indonesian origin were studied. HLA-B27 subtyping was performed by polymerase chain reaction in combination with sequence specific oligonucleotide probes. Results. In one family, members with B * 2704, B * 2706, or both occurred. In the other family B * 2704, B * 2706, and B * 2708 were present. In both families SpA was seen only in B * 2704 positive members, while the B * 2706 and B * 2708 positive members were healthy, except some B * 2704/B * 2706 or B * 2704/B * 2708 heterozygotes. Conclusion. The pathogenic influence of B * 2704 is thus dominant over the supposed protective influence of B * 2706. It is probable that B * 2704 can present pathogenetic peptides, while a protective influence of B * 2706 does not exist. B * 2708, which was until now described in only a few cases, behaved in this study as B * 2706 and is probably not associated with SpA.