Background: Oral submucous fibrosis (OSF) is an insidious, pre-cancerous, chronic disease that may affect the entire oral cavity and sometimes extend to the pharynx. It has been reported to be associated with immune function. Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4; CD (cluster of differentiation) 152) is a negative regulator of T-lymphocyte activation. Particular genotypes of the locus encoding the CTLA-4 glycoprotein have been associated with susceptibility to various autoimmune diseases. This study was designed to investigate the role of CTLA-4 polymorphism in susceptibility to OSF.
Methods: We genotyped 62 patients with OSF and 147 healthy controls for allelic determinants at the exon 1 +49 polymorphism site by restriction fragment length polymorphism. Genotype and phenotype frequencies were evaluated with Chi-squared test.
Results: The G allele at position +49 of exon 1 was significantly associated with OSF. The frequency of A/A homozygotes was higher in controls than in patients (17.0% vs. 3.2%; chi(2) = 7.65, P = 0.02); the G phenotype was more frequent in patients than in controls (96.8% vs. 83.0%; chi(2) = 9.31, P = 0.002). Compared with controls, the G allele genotype and phenotype frequencies were increased in patients with OSF.
Conclusion: This is the first report that the CTLA-4 +49 G allele confers an increased risk of OSF in Taiwan.