Meta-analysis of the transforming growth factor-β1 polymorphisms and susceptibility to Alzheimer's disease

The association between transforming growth factor-β1 (TGF-β1) gene polymorphisms and Alzheimer's disease (AD) risk has been widely reported, but results were somewhat controversial and underpowered. To derive a more precise estimation of the relationship between TGF-β1 polymorphisms and AD risk, we conducted a meta-analysis of all available case-control studies relating the T869C and/or C-509T polymorphisms of the TGF-β1 gene to the risk of developing AD. Eligible articles were identified by search of databases including Pub Med, Web of Science, the Chinese Biomedical Database (CBM), Chinese National Knowledge Infrastructure (CNKI) and the Wan Fang (Chinese) for the period up to March 2012. Finally, a total of 14 articles were identified, 10 with 1,657 cases and 6,971 controls for T869C polymorphism and 8 with 2,618 cases and 7,473 controls for C-509T polymorphism. The pooled ORs were performed for the allele contrasts, additive genetic model, dominant genetic model and recessive genetic model, respectively. Subgroup analysis was also performed by ethnicity. With respect to T869C and C-509T polymorphism, the combined results showed that there were no significant differences in genotype distribution between AD and control based on all studies. When stratifying for the race, there were also no statistically significant differences in genotype distribution between AD and controls. This meta-analysis did not provide an evidence of confirming association between the T869C and/or C-509T polymorphisms of the TGF-β1 gene and AD.