Association between polymorphisms of trinucleotide repeat containing 9 gene and breast cancer risk: evidence from 62,005 subjects

Trinucleotide repeat containing 9 (TNRC9) is a gene located at chromosome 16q12. Although of an uncertain function, it is a newly described risk factor for breast cancer. It contains a putative high-mobility group box motif, suggesting its possible role as transcription factor; it has been implicated in breast cancer metastasis. Published studies on the association between TNRC9 polymorphisms and breast cancer risk remain inconclusive, and a meta-analysis is required to verify the association. This pioneering research performed a meta-analysis of eight studies comprising a total of 25,828 cases and 36,177 controls. Significantly elevated breast cancer risk was associated with TNRC9 rs3803662 polymorphism when all studies were pooled in the meta-analysis (T vs. C allele contrast model: OR 1.18, 95% CI 1.09-1.28; TT vs. CC homozygote codominant model: OR 1.26, 95% CI 1.02-1.55; TT vs. CC+CT recessive model: OR 1.23, 95% CI 1.06-1.42). For TNRC9 rs12443621 polymorphism, no significant association was detected in all genetic models. For TNRC9 rs12443621 polymorphism, meanwhile, no significant association was observed in all comparison models. Conclusively, this meta-analysis suggests that TNRC9 rs3803662 polymorphism was significantly correlated with breast cancer risk and the variant T allele of TNRC9 rs3803662 polymorphism is a low-penetrant risk factor for developing breast cancer. There is no significant association between TNRC9 rs12443621 and rs8051542 polymorphisms and risk of breast cancer in current literature.