OBJECTIVE

We surveyed B27 and its subtypes in 5 ethnic groups in Taiwan.

METHODS

Blood was obtained from 281 Aborigine people of the Atayal tribe (I-Lan), 141 Paiwan (Ping-Ton), 38 Rukai (Ping-Ton), and 40 Yami (Orchid Island), and also 47 B27+ healthy Han Chinese subjects and 82 B27+ Han patients with ankylosing spondylitis (AS). HLA-B27 and its subtypes were determined by standard methods.

RESULTS

A much higher prevalence of B27 was found among the Atayal Aborigines (9.2%), which was significantly different from a lower prevalence in the Paiwan (2.1%; p = 0.004) and even higher than that of Han Chinese (5.59%; p = 0.04). No blood sample from the 38 Rukai Aborigines showed any B27. B2704 was the only subtype (100%) found in the 28 healthy Aborigines and 2 Aborigine patients with AS. However, in Chinese subjects, 40 of 47 (85%) B27+ healthy subjects were B2704, and 7 of 47 (15%) were B2705. In Chinese B27+ AS patients, 77 of 82 (94%) were B2704 and 5 of 82 (6%) were B2705. No other subtypes were found. Only the Aborigines without AS carrying B2704 showed a significant difference from the Chinese without AS carrying B2704 (p = 0.041).

CONCLUSION

The different prevalence of B27, but similar frequency of the B2704 subtype, between Aborigines and Han Chinese suggests Aborigines are a unique population and may originate from an Asian country, possibly mainland China.