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/B2708 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.