@article {Jaakkola775, author = {E Jaakkola and I Herzberg and K Laiho and M C N M Barnardo and J J Pointon and M Kauppi and K Kaarela and E Tuomilehto-Wolf and J Tuomilehto and B P Wordsworth and M A Brown}, title = {Finnish HLA studies confirm the increased risk conferred by HLA-B27 homozygosity in ankylosing spondylitis}, volume = {65}, number = {6}, pages = {775--780}, year = {2006}, doi = {10.1136/ard.2005.041103}, publisher = {BMJ Publishing Group Ltd}, abstract = {Objective: To determine the influence of HLA-B27 homozygosity and HLA-DRB1 alleles in the susceptibility to, and severity of, ankylosing spondylitis in a Finnish population.Methods: 673 individuals from 261 families with ankylosing spondylitis were genotyped for HLA-DRB1 alleles and HLA-B27 heterozygosity/homozygosity. The frequencies of HLA-B27 homozygotes in probands from these families were compared with the expected number of HLA-B27 homozygotes in controls under Hardy{\textendash}Weinberg equilibrium (HWE). The effect of HLA-DRB1 alleles was assessed using a logistic regression procedure conditioned on HLA-B27 and case{\textendash}control analysis.Results:HLA-B27 was detected in 93\% of cases of ankylosing spondylitis. An overrepresentation of HLA-B27 homozygotes was noted in ankylosing spondylitis (11\%) compared with the expected number of HLA-B27 homozygotes under HWE (4\%) (odds ratio (OR) = 3.3 (95\% confidence interval, 1.6 to 6.8), p = 0.002). HLA-B27 homozygosity was marginally associated with reduced BASDAI (HLA-B27 homozygotes, 4.5 (1.6); HLA-B27 heterozygotes, 5.4 (1.8) (mean (SD)), p = 0.05). Acute anterior uveitis (AAU) was present in significantly more HLA-B27 positive cases (50\%) than HLA-B27 negative cases (16\%) (OR = 5.4 (1.7 to 17), p\<0.004). HLA-B27 positive cases had a lower average age of symptom onset (26.7 (8.0) years) compared with HLA-B27 negative cases (35.7 (11.2) years) (p\<0.0001).Conclusions:HLA-B27 homozygosity is associated with a moderately increased risk of ankylosing spondylitis compared with HLA-B27 heterozygosity. HLA-B27 positive cases had an earlier age of onset of ankylosing spondylitis than HLA-B27 negative cases and were more likely to develop AAU. HLA-DRB1 alleles may influence the age of symptom onset of ankylosing spondylitis.}, issn = {0003-4967}, URL = {https://ard.bmj.com/content/65/6/775}, eprint = {https://ard.bmj.com/content/65/6/775.full.pdf}, journal = {Annals of the Rheumatic Diseases} }