Lack of association of the G22A polymorphism of the ADA gene in patients with ankylosing spondylitis.

Genes located outside the HLA region (6p21) have been considered as candidates for susceptibility to ankylosing spondylitis. We tested the hypothesis that the G22A polymorphism of the adenosine deaminase gene (ADA; 20q13.11) is associated with ankylosing spondylitis in 166 Brazilian subjects genotyped for the HLA*27 gene (47 patients and 119 controls matched for gender, age and geographic origin). The HLA-B*27 gene and the G22A ADA polymorphism were identified by PCR with sequence-specific oligonucleotide probes and PCR-RFLP, respectively. There were no significant differences in frequencies of ADA genotypes [odds ratio (OR) = 1.200, 95% confidence interval (CI) = 0.3102-4.643, P > 0.8] and ADA*01 and ADA*02 alleles (OR = 1.192, 95%CI = 0.3155-4.505, P > 0.8) in patients versus controls. We conclude that the G22A polymorphism is not associated with ankylosing spondylitis.