Allelic variation at the TAP 1 locus influences disease phenotype in HLA-B27 positive individuals with ankylosing spondylitis.

The objective was to determine the role of the TAP 1 gene in influencing the phenotype of disease in adult patients with ankylosing spondylitis (AS). The distribution of TAP 1 gene alleles was determined using the PCR RFLP method and restriction enzymes Bcl I and Acc I. The study population included 115 HLA-B27 positive patients with well-documented AS and 41 HLA-B27 positive normal controls. No significant difference in distribution of TAP 1 alleles was noted in comparisons of all AS patients with normal controls. However, AS patients with extraspinal disease were noted to have a significantly increased prevalence of the TAP 1B allele (17.0%) as compared to AS patients without extraspinal disease (2.9%) (P = 0.005) or normal controls (1.9%) (P = 0.005). Polymorphism at the TAP 1 locus may influence disease outcome in patients with AS.