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HLA-B27 homozygosity has no influence on clinical manifestations and functional disability in ankylosing spondylitis.

OBJECTIVE
There is an established association between the development of ankylosing spondylitis (AS) and the HLA-B27 allele, but whether or not homozygosity for HLA B27 has any additional effects on the clinical manifestations of AS is unclear. The aim of this study was to determine the influence of HLA-B27 homozygosity on the clinical manifestations of AS in Korea.


METHODS
A total of 490 patients were enrolled in this study. Genotyping was carried out using polymerase chain reaction-sequence specific primers (PCR-SSP) to assess HLA-B27 homozygosity or heterozygosity. One PCR reaction was undertaken to determine the HLA-B27 carrier status, and 5 group-specific PCR reactions were carried out to determine all of the other HLA-B alleles. Clinical manifestations of AS and BASFI were also evaluated according to homozygosity or heterozygosity for HLA-B27.


RESULTS
HLA-B27 positive patients had a significantly younger age at symptom onset, more uveitis, and a higher frequency of hip joint involvement than HLA-B27 negative patients. One hundred and forty-six (29.8%) patients were homozygous for HLA-B27. No significant association between HLA-B27 homozygosity or heterozygosity and a history of peripheral arthritis, acute anterior uveitis, age at onset, or the Bath Ankylosing Spondylitis Functional Index (BASFI) was found.


CONCLUSIONS
Homozygosity for HLA-B27 does not affect the clinical manifestations of AS in Korean patients.