CYP19A1基因 R264C在中国上海BRCA1/2基因突变阴性的遗传倾向乳腺癌中的作用

目的研究CYP19A1基因R264C的（C→T）单核苷酸多态性基因型在上海地区BRCA1／BR-CA2基因突变阴性的遗传倾向乳腺癌人群中的分布及其与乳腺癌发病风险的相关性。方法对114例无BRCA1／2突变的家族性／早发性乳腺癌患者和121名正常对照者进行CYP19A1基因第7外显子的聚合酶链反应扩增，随后进行DNA直接测序鉴定其R264C的单核苷酸多态性基因型，比较基因型分布和发病风险的关系；危险度比值比（odd ratio，OR）及95％可信区间（confidence interval，CI）应用非条件Logistie回归分析计算。结果CYP19A1基因R264C多态的CC、CT、TT基因型在病例组中的分布频率分别为84（77．8％），22（20．4％），2（1、8％）；在对照组的分布频率分别为87（77．7％），24（21、4％），1（0．9％）；在研究的总人群中，CT基因型的频率为20．9％（46／220），TT基因型的频率为1．4％（3／220）。以CC基因型为参照，CT或TT基因型没有显著性地提高乳腺癌的发病危险，其中携带CT基因型风险为（OR=1．16，95％CI：0．53。2．55），携带TT基因型风险为（OR=1．44，95％CI：0．12-17．15）；经过月经状态和身体质量指数分层，也未能发现其与乳腺癌发病的相关性。结论CYP19A1基因R264C的单核苷酸多态性在中国汉族人群中的分布有别于其他种族，有其自身的分布特点；R264C可能与上海地区中国汉族人群乳腺癌发生的遗传易感性无关，尚不足作为低外显率的乳腺癌易感基因位点，不建议作为未来临床基因筛查的候选指标。

Effect of R264C polymorphism in CYP19A1 gene on BRCA1/2-negative hereditary breast cancer from Shanghai population of China

Objective Aromatase, encoded by CYP19A1, play an important role in estrogens biosynthesis from androgens. The present study is to investigate effect of R264C single nucleotide polymorphism inCYP19A1 gene on genetic susceptibility for hereditary breast cancer without BRCA1/2 mutant. Methods One hundred and fourteen BRCA1/2-negative hereditary breast cancer patients from independent families and 121 age-matched healthy control subjects were analyzed. Genotype analysis was performed through polymerase chain reaction (PCR) and then DNA direct sequencing. The odd-ratios (OR) and 95% confidence intervals (CI) were calculated by unconditional Logistic regression model. Results The frequency of R264C single nucleotide polymorphism CC, CT and TT genotype in case group and controls was 84(77.8%),22(20.4%),2(1.8%) and 87(77.7%),24(21.4%),1(0.9%), respectively. CT genotype (OR= 1.16, 95%CI:0.53-2.55) and TT genotype (OR=1.44, 95%CI:0.12-17.15) did not confer a significantly increased risk for breast cancer. No significant association was found between T allele and susceptibility for breast cancer under analysis according to menopausal status and body mass index. Conclusion R264C polymorphism inCYP19A1 gene is not a candidate locus for low penetrance breast cancer susceptibility in Shanghai group of Chinese population and not recommended in clinical genetic test. Homozygous T allele of R264C is not common in Shanghai group of Chinese population.