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

Objective. Studies in Southeast Asia showed that HLA-B*2704 is positively a ssociated with spondyloarthropathy (SpA), while B*2706 does not occur in su ch patients. In view of the absence of an association between B*2706 and Sp A it was suggested that B*2706 protects against the disease, while it is su pposed that B*2706 presents pathogenetic peptides. We studied families in w hich both B*2704 and B*2706 occurred to see whether in B*2704/B*2706 hetero zygotes the effect of one of the subtypes shows a preponderance over the ot her. Methods. Two families of mixed Chinese/Indonesian origin were studied, HLA- B27 subtyping was performed by polymerase chain reaction in combination wit h sequence specific oligonucleotide probes. Results. In one family, members with B*2704, B*2706, or both occurred. In t he other family B*2704, B*2706, and B*2708 were present. In both families S pA was seen only in B*2704 positive members, while the B*2706 and B*2708 po sitive members were healthy, except some B*2704/B*2706 or B*2704/B*2708 het erozygotes. Conclusion. The pathogenic influence of B*2704 is thus dominant over the su pposed protective influence of B*2706, It is probable that B*2704 can prese nt pathogenetic peptides, while a protective influence of B*2706 does not e xist. 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.