[Correlation anslysis of sporadic breast cancer and BRCA1 gene plymorphisms in the Han Nationality and the Mongol Nationality of Inner Mongolia Region].

OBJECTIVE: To study the correlationship between the BRCA1 gene polymorphisms, especially in 2731 loci (rs799917), and sporadic breast cancer in the Han nationality and the Mongol nationality of the Inner Mongolia region. METHODS: Using the prospective study method, 103 cases of patients with sporadic breast cancer (case group) and 103 cases of normal physical examination people (control group) were enrolled. PCR and direct sequencing method were used for analyzing the correlationship of 2731 loci polymorphisms of BRCA1 and sporadic breast cancer in our zone. RESULTS: In the case group, the age stratification, pathologic stage, immunohistochemistry and the distribution of lymph node metastasis had no significant difference in two ethnic group (P> 0.05). The age stratification of control group also had no significant difference in two ethnic group (P>0. 05). There was no statistically significant difference in age stratification of the case group and the control group (P>0.05). In the Inner Mongolia region, BRCA1 gene 2731 loci genotypes check out three genotypes: namely TT, CT and CC. The frequencies of genotype TT, CT, CC in the case group were 13.1%, 26.2%, 60.7% ( the Han nationality) and 16.7%, 28.6%, 54.7% (the Mongol nationality), respectively. Meanwhile the frequencies of allele T and allele C were 71.8% and 28.2%. In the control group, the frequencies of genotype TT, CT, CC were 18.0%, 31.1%, 50.9% ( the Han nationality) and 23.8%, 38.1%, 38.1% ( the Mongol nationality), respectively, and the frequencies of allele T and allele C were 62.9% and 37.1%. BRCA1 gene 2 731 loci gene polymorphism had no significant difference in two groups (χ(2)=3.438, P=0.752), but T allele frequency distribution in the case group was significantly increased (χ(2)=4.185, P=0.041). CONCLUSION: There is no obvious correlation between the BRCA1 gene 2731 loci and sporadic breast cancer in the Han nationality and the Mongol nationality of the Inner Mongolia region. C allele of BRCA1 gene 2731 loci may be one of the protective gene of sporadic breast cancer.