Objective: To investigate the association between transporter associated with antigen processing(TAP) gene and ankylosing spondylitis(AS) as well as HLA-B27.
Methods: PCR-SSO was used to analyze the frequencies of TAP alleles and variant amino acids of TAP in 48 patients (B27(+)) with AS and 123 normal individuals (B27(+) or B27(-)).
Results: The phenotypes of Ile/Ile, Asp/Asp were over-presented for TAP1 and Val/Val, Ala/Thr, Stop/Stop for TAP2 in Han nationality. For each TAP there were four alleles: TAP1*0101, TAP1*0201, TAP1*0301, TAP1*0401, and TAP2*0101, TAP2*0102, TAP2*0201, TAP2*0202. In the research subjects, hybridization blanks accounted for 9.9%(17/171) of TAP1 and 15.8%(27/171) of TAP2. No difference was found in the distribution of TAP alleles between the AS patients(B27(+)) and normal controls(B27(+) or B27(-)). In the patients group the frequency of phenotype in codon of 333 (Val/Val) was significantly decreased as compared with that of the healthy controls(B27(+))(P<0.05). In addition, the frequency of phenotype Ala/Ala(665) was significantly decreased and that of Ala/Thr was significantly increased in normal controls(B27(-)), compared with those in normal controls(B27(+))(P<0.05).
Conclusion: It is possible that there are new TAP alleles in Han nationality. No association was found between TAP alleles and AS. And the homozygosity for codon 333 which is Val/Val seems to offer resistance to AS among those HLA-B27(+) individuals. In normal individuals, negative correlation was found between heterozygote Ala/Thr and B27, and possibly there was positive correlation between phenotype Ala/Ala and B27.