Background: Transporter antigen peptide 1 (TAPI) and TAP2 gene products form a transporter molecule involved in antigen presentation. Polymorphic residues have been described in both genes and could have functional consequences in the immune response. Objective: We designed a case-control study to investigate the potential association of polymorphism of the TAPI gene with atopy. Methods: We used the amplification refractory mutation system polymerase chain reaction to characterize TAPI gene polymorphism in 84 unrelated Tunisian patients with atopy and 81 healthy control subjects. Results: Analysis of TAPI polymorphism in Tunisian patients with atopy and in unaffected control subjects demonstrates a high relative risk (RR) of atopy in carriers of a codon (d) corresponding to a glycine at position 637 of the TAP1-B and TAP1-D alleles. The relative risk of allergic asthma is markedly higher in homozygotes (did) (RR = 22; p ≤ 0.0001). The TAP1-D allele, not observed in European populations, has a frequency of 5% in the Tunisian control subject group. A major increase of the frequency (f) of the D allele is observed in patients with allergic asthma (f = 35%) and in those with allergic rhinitis (f = 22%), indicating a high relative risk of allergic asthma (RR = 10.2; p ≤ 0.0001) and of allergic rhinitis (RR = 5.4; p ≤ 0.005) in individuals carrying this allele. DD homozygotes were found only among patients with allergic asthma (23% of patients with asthma). Further evidence of the strong association between TAP1 polymorphism and atopy was provided by the finding that atopy is transmitted by inheritance of the glycine-637 marker. Conclusions: Tunisian persons carrying the glycine-637 of the TAPI protein may have an increased risk of atopy. Specific association was found between the homozygous TAPI DID genotype and allergic asthma.
- Allergic asthma
- Amplification refractory mutation system polymerase chain reaction
- TAP1 polymorphism
ASJC Scopus subject areas
- Immunology and Allergy