Cytotoxic T-lymphocyte antigen 4 gene +49A/G polymorphism significantly associated with susceptibility to primary biliary cirrhosis: a meta-analysis

Objective: To evaluate comprehensively the association of cytotoxic T-lymphocyte antigen 4 (CTLA-4) +49A/G polymorphism with susceptibility to primary biliary cirrhosis (PBC).

Methods: PubMed was used to search for the relevant published articles. The risk of PBC association with the CTLA-4+49A/G polymorphism was estimated for each study in a random-effects model. Odds ratio (OR) and 95% confidence interval (CI) were estimated for each study. Risks to PBC were estimated by stratified analysis in patients with different ethnicity and antimitochondrial antibody (AMA) status, as well as histological stages.

Results: A total of 12 articles were included in the study. An association between PBC and CTLA-4 G allele was found, overall OR = 1.20, 95% CI 1.03-1.41 (P = 0.02). However, stratification by ethnicity indicated a significant association between the G allele and PBC in Asians (OR = 1.36, 95% CI 1.12-1.65, P = 0.002), but not in Caucasians (OR = 1.15, 95% CI 0.95-1.39, P = 0.15). Moreover, AMA positive patients carrying G allele were more susceptible to PBC compared with AMA negative patients (OR = 1.23, 95% CI 1.06-1.43, P = 0.007; OR = 0.98, 95% CI 0.71-1.34, P = 0.88, respectively).

Conclusions: Polymorphism in exon 1 of CTLA-4 gene at position 49 may act as a candidate of susceptibility locus to PBC. However, larger studies with participants of varying ethnicity and stratified by clinical and laboratory characteristics are needed to validate our findings.