Usefulness of human leucocyte antigen-B27 subtypes in predicting ankylosing spondylitis: Taiwan experience.

BACKGROUND

Genetic factors are clearly attributed to the susceptibility of ankylosing spondylitis (AS). The human leucocyte antigen (HLA)-B27 proved to be the very useful marker for diagnosing AS. The aim of this study was to determine the prevalence of HLA-B27 subtypes in Taiwan and to investigate whether these subtypes may be of help in predicting the diagnosis of AS.

METHODS

A total of 314 patients with AS and a control group of 71 subjects positive for HLA-B27 detected by flow cytometry analysis were recruited for the study. HLA-B27 subtypes were confirmed by the polymerase chain reaction-sequence-specific primers and sequence-specific oligonucleotide probing.

RESULTS

Four B27 alleles were identified: B2704, B2705, B2706 and B2707. HLA-B2704 was the predominant allele. There were significant differences in the distribution of HLA-B27 subtypes between patients with AS and controls. Five of them who were homozygous for the B2704 allele were solely found in AS group but not in controls. Statistical analysis showed that B*2704 was positively associated with AS, which suggested an increased possibility of having AS. Other HLA-B27 subtypes showed no strong correlation with AS.

CONCLUSION

In the Taiwanese population, susceptibility to AS was determined by the presence of HLA-B2704. Although B2706 was reported to have a negative association with AS in Taiwanese, Thai and Chinese Singaporean populations, we report, in our study, two AS patients with B*2706 (0.6%). Disease heterogeneity suggests that other than genetic background, many pathogenic factors could be associated with AS. This may need to be investigated with a larger group of patients with AS and controls.