中国上海家族性乳腺癌BRCA1和BRCA2基因的突变

目的研究上海地区家族性乳腺癌中BRCA1／BRCA2基因的突变位点及携带情况。方法研究对象来自35个汉族家族性乳腺癌家系，家系中至少有一个一级亲属乳腺癌患病史。共35例患者，其中13例发病年龄≤加岁。由静脉血提取基因组DNA，对BRCA1／BRCA2基因的全部编码序列进行扩增。扩增产物突变分析先由变性高效液相色谱分析进行筛查，之后进行DNA直接测序证实。结果在BRCA1基因中发现有4个突变位点，其中2个为新发现位点——拼接点突变（IVS17-1G〉T；IVS21＋1G〉C）；另两个为已报道的致病突变位点——移码突变（1100delAT；5640delA）。BRCA2基因的1个致病突变位点位于11号外显子上，为移码突变（5802delAATT）。另外，共发现有12个新的单核苷重复多态位点，都未引起氨基酸编码改变；其中，8个在BRCA1基因上，4个在BRCA2基因上。在家族性乳腺癌中，BRCA1突变频率（11．4％）高于BRCA2基因（2．9％）。结论新发现的2个BRCA1基因的拼接点突变可能是中国上海人群家族性乳腺癌的特有突变位点；在我国上海地区人群中，BRCA1基因突变起着比BRCA2基因更大的作用；该研究丰富了中国人群中BRCA基因的突变谱，并为未来的临床基因检测提供了筛查模式。

BRCA1 and BRCA2 gene mutations of familial breast cancer from Shanghai in China

OBJECTIVE: To investigate the prevalence of BRCA1 and BRCA2 gene mutations among breast cancer patients with affected relatives in Shanghai of China. METHODS: Thirty-five breast cancer patients who had at least one first-degree relative affected were analyzed, among whom 13 patients suffered from breast cancer at age of less than 40 years. A comprehensive BRCA1 and BRCA2 mutation analysis was performed through denaturing high-performance liquid chromatography (DHPLC) and subsequent DNA direct sequencing. RESULTS: Four mutations in BRCA1 gene, including 2 novel splice-site mutations (IVS17-1G>T, IVS21+1G>C) and 2 frameshift mutations (1100delAT; 5640delA) were identified. One frameshift mutation (5802delAATT) was detected in exon 11 of BRCA2. Additional 12 novel single nucleotide polymorphisms(SNPs) were detected, including a novel unclassified variant and 7 novel intronic variants in BRCA1, and 4 novel intronic variants in BRCA2, with which all caused no alteration of amino acid coding. The mutation frequency of BRCA1 and BRCA2 in patients with family history was 11.4% and 2.9%, respectively. CONCLUSION: Two novel mutations in BRCA1 may be mutations characterized to familial breast cancer of Chinese Shanghai population. The BRCA2 may contribute to mutation less than BRCA1 in familial breast cancer. Our data contribute to information on mutation spectrum of BRCA gene in Chinese population and also offer a recommended screening mode for clinical genetic testing policy in China.