ABSTRACT
<p><b>OBJECTIVE</b>To investigate the association between single nucleotide polymorphisms (SNPs) of BARD1 gene and susceptibility of early-onset breast cancer in Uygur women in Xinjiang.</p><p><b>METHODS</b>A case-control study was designed to explore the genotypes of Pro24Ser (C/T), Arg378Ser (G/C) and Val507Met (G/A) of BARD1 gene, detected by PCR-restriction fragment length polymorphism (PCR-RFLP) assay, in 144 early-onset breast cancer cases of Uygur women (≤ 40 years) and 136 cancer-free controls matched by age and ethnicity. The association between SNPs of BARD1 gene and risk of early-onset breast cancer in Uygur women was analyzed by unconditional logistic regression model.</p><p><b>RESULTS</b>Early age at menarche, late age at first pregnancy, and positive family history of cancer may be important risk factors of early-onset breast cancer in Uygur women in Xinjiang. The frequencies of genotypes of Pro24Ser (C/T), Arg378Ser (G/C) and Val507Met (G/A) of BARD1 gene showed significant differences between the cancer cases and cancer-free controls (P < 0.05). Compared with wild-type genotype Pro24Ser CC, it showed a lower incidence of early-onset breast cancer in Uygur women with variant genotypes of Pro24Ser TT (OR = 0.117, 95%CI = 0.058 - 0.236), and dominance-genotype CT+TT (OR = 0.279, 95%CI = 0.157 - 0.494), or Arg378Ser CC (OR = 0.348, 95%CI = 0.145 - 0.834) and Val507Met AA(OR = 0.359, 95%CI = 0.167 - 0.774). Furthermore, SNPS in three polymorphisms would have synergistic effects on the risk of breast cancer. In addition, the SNP-SNP interactions of dominance-genotypes (CT+TT, GC+CC and GA+AA) showed a 52.1% lower incidence of early-onset breast cancer in Uygur women (OR = 0.479, 95%CI = 0.230 - 0.995). Stratified analysis indicated that the protective effect of carrying T variant genotype (CT/TT) in Pro24Ser and carrying C variant genotype (GC/CC) in Arg378Ser were more evident in subjects with early age at menarche and negative family history of cancer. With an older menarche age, the protective effect was weaker.</p><p><b>CONCLUSIONS</b>SNPs of Pro24Ser(C/T), Arg378Ser (G/C) and Val507Met (G/A) of BARD1 gene are associated with significantly decreased risk of early-onset breast cancer in Uygur women in Xinjiang. Early age at menarche and negative family history of cancer can enhance the protective effect of mutant allele.</p>