中国湖南家族性和早发性乳腺癌BRCA1和BRCA2基因突变分析

背景与目的:BRCA1和BRCA2基因是已经证实的乳腺癌遗传易感基因,与家族性及早发性乳腺癌密切相关.本研究旨在分析中国湖南省家族性和早发性乳腺癌中BRCA1和BRCA2基因的突变位点及携带情况.方法:以来自湖南地区的50例家族性和早发性乳腺癌(发病年龄≤35岁)为研究对象,其中26例(52%)有乳腺痛家族史.由静脉血提取基因组DNA,对BRCA1和BRCA2基因的全部编码序列进行扩增.突变分析由变性高效液相色谱分析(DHPLC)进行预筛,之后进行DNA测序证实.结果:在50例乳腺癌患者中发现有5种致病性突变,其中2种为新发现突变--BRCA2基因无义突变2372C>G和移码突变2808delACAA.BRCA1基因中发现一种已报道的无义突变220C>T;其他两种为已报道的BRCA2移码突变位点1796delTTTAT和6275delTT.我们还发现4个未知功能的突变位点(UV)及11个基因多态性位点.湖南家族性乳腺癌中BRCA1突变率4%低于BRCA2突变率16%. 结论:在中国湖南人群中,BRCA2基因的突变对于遗传性乳腺癌的发生可能具有较重要意义:新发现的2个突变位点可能是中国人群中的特有突变;湖南地区BRCA1在家族性乳腺癌中突变率明显低于国内外报道,而BRCA2突变发生率与西方国家相近,但明显高于国内其他地区,这可能是中国湖南人群中的特有特征.     

家族性乳腺癌患者及家系成员乳腺癌易感基因携带情况调查

目的 乳腺癌易感基因1(breast cancer susceptibility gene 1,BRCA1)和BRCA2基因已经证实与家族性乳腺癌密切相关.本研究旨在分析中国汉族家族性乳腺癌患者及家系成员BRCA1和BRCA2突变特征及携带情况.方法 收集2013 12-02-2015-06-08军事医学科学院附属医院确诊的中国汉族家族性乳腺癌患者55例及家系成员48名,共计103例样本.柚取外周静脉血提取DNA,应用聚合酶链反应(polymerase chain reaction,PCR) DNA直接测序方法检测BRCA1和BRCA2基因全编码外显子序列.结果 55例家族性乳腺癌患者中发现5个BRCA基因致病性突变位点,1个突变位点乳腺癌信息库中见报道(BRCA1:4730insG),4个为新发现突变位点(BRCA1:1937insC,4538insAG;BRCA2:1382delA,2820delA).家族性乳腺癌患者BRCA1/2突变率为9.09％(BRCA1,5.45％;BRCA2,3.64％),其中三阴性乳腺癌患者突变率为22.22％(x2 =1.99,P=0.20),早发性乳腺癌患者(≤35岁)突变率为20.00％,x2=0.79,P=0.39.48例家系成员检测到3个新发现突变位点(BRCA1:1370insA,3459insA;BRCA2:6502insT),总突变率为6.25％.结论 中国汉族家族性乳腺癌患者BRCA基因突变率显著低于国外,应重点关注有家族史的三阴性乳腺癌患者和早发性乳腺癌患者;家系成员中发现BRCA基因致病性突变,家系成员突变率和发病风险有待进一步研究,应引起重视.     

中国家族性和早发性乳腺癌BRCA1基因突变的研究

目的　研究中国家族性和早发性乳腺癌患者的BRCA1基因突变情况。方法　选取 4 1例家族性和早发性乳腺癌患者的外周血单个核细胞DNA ,应用PCR SSCP和DNA序列测定方法 ,对BRCA1基因全序列进行突变检测和分析。结果　 4 1例乳腺癌患者中 ,3例发生BRCA1疾病相关性突变 ,其中年龄 <35岁的患者 2例 ,具有乳腺癌家族史的患者 1例。结论　中国早发性乳腺癌患者的BRCA1突变发生率与西方国家相近 ,而家族性乳腺癌患者的突变发生率明显低于西方国家。     

219例中国汉族遗传性乳腺癌患者BRCA1和BRCA2突变的研究

背景与目的:BRCA1和BRCA2是通过家系连锁分析确定的与乳腺癌、卵巢癌家族高度相关的两个基因,目前国内关于中国汉族遗传性乳腺癌BRCA1和BRCA2突变研究的样本量都不大,而且大部分研究仅检测了BRCA1或部分BRCA2,并不能真正反映汉族遗传性乳腺癌的遗传特征.本研究旨在建立中国汉族人群遗传性乳腺癌患者中BRCA1和BRCA2的突变谱,并确定高危突变的家族特征.方法:来自3个中心的219个独立的家系纳入本研究,每个家系中的先证者进行BRCA1和BRCA2全外显子以及外显子内含子拼接区的突变检测.结果:219例患者检测到23例致病性突变,7例位于BRCA1,16例位于BRCA2.BRCA1和BRCA2的突变率与家系特征有关,家族性乳腺癌/卵巢癌患者BRCA1和BRCA2的突变率分别14.3% (1/7)和28.6% (2/7);早发性遗传性乳腺癌患者BRCA1的突变率为22.2%(2/9);而在非早发性遗传性乳腺癌患者BRCA2的突变率明显高于BRCA1(7.8% ,6/77 vs 0%, 0/77, P=0.028).结论:BRCA1和BRCA2突变率与家族特征有关,在非早发性遗传性乳腺癌家族中BRCA2突变值得关注.     

河北省家族性和散发性乳腺癌易感基因1/2突变的研究

目的探讨河北省家族性和散发性乳腺癌患者乳腺癌易感基因(BRCA)1/2的突变位点及携带情况。方法采用聚合酶链反应-单链构象多态性分析和基因测序技术对18例家族性乳腺癌患者、50例散发性乳腺癌患者、23例乳腺良性疾病患者及20例健康对照组血样标本的基因组DNA进行BRCA1/2基因突变的检测。定性资料采用χ2检验和Fisher's确切概率法进行分析,定量资料采用t检验进行分析。结果 68例乳腺癌患者基因突变率为7.35%(5/68),均发生在BRCA1基因(162ATTTTT;4142GTTGTG;4196CAACAT;4196delA,4142GTTGTG;5379GAAAAA),无BRCA2基因突变,BRCA1基因的突变率高于BRCA2基因(χ2=4.829,P=0.028);其中,18例家族性乳腺癌基因突变3例,50例散发性乳腺癌突变2例,二者间差异无统计学意义(χ2=3.117,P=0.111)。乳腺良性疾病患者未见BRCA1/2基因突变。健康对照组未见BRCA1基因突变,但有1例BRCA2基因突变[TTTCAGA-TGTCAA(6291insG,6294delG)]。家族性乳腺癌患者、散发性乳腺癌患者、乳腺良性疾病患者和健康对照组的BRCA1基因突变率差异有统计学意义(χ2=8.248,P=0.041)。在1例家族性乳腺癌标本中发现1个核苷酸多态性位点,位于BRCA1第20外显子下游第35个碱基处GA(IVS20+35GA)。结论本研究丰富了中国人群BRCA1/2基因的突变谱,并为将来乳腺癌的普查和临床基因检测提供了筛查模式。     

苏州地区乳腺癌患者BRCA1和BRCA2基因突变的分析

目的 探讨中国苏州地区乳腺癌患者乳腺癌易感基因1(BRCA1)和乳腺癌易感基因2(BRCA2)基因的突变位点及携带情况，并对携带致病突变基因患者的家系成员进行基因筛查和风险管理。方法 收集2018年7月至2021年10月确诊的85例乳腺癌患者，其中早发性乳腺癌40例，家族性乳腺癌36例，三阴性乳腺癌35例。采用高通量测序技术，对患者外周血中BRCA1和BRCA2基因的外显子及其部分内含子序列进行检测，将检测到的致病突变与ClinVar数据库进行对照，确定是否为新发现的致病突变。通过对家系先证者进行遗传咨询和肿瘤易感基因检测，进一步对携带致病基因患者的健康家系成员进行BRCA基因突变筛查。结果 85例乳腺癌患者中BRCA1和BRCA2的总致病突变率为21.2%(18/85),其中BRCA1致病突变率为11.8%(10/85), BRCA2致病突变率为9.4%(8/85)。在18例致病性突变患者中发现3个新发位点，分别为BRCA1基因c.1559dupA,BRCA2基因c.8939-8941delinsT和BRCA2基因c.3677-3678insATGAAAT。进一步对携带BRCA1/B...     

家族性乳腺癌BRCA1/BRCA2基因突变的研究

目的:研究家族性乳腺癌患者BRCA1/ BRCA2基因的突变位点及携带情况.方法:应用聚合酶链反应-单链构象多态性分析(single strand confor- mation polymorphism analysis of polymerase chain reaction products,PCR-SSCP)和基因测序技术,对12个家族性乳腺癌家系的13例患者进行BRCA基因检测.结果:实验发现1个突变位点(4193insA)和2个核苷酸多态性位点(4165T>A,5416C>A).结论:河北地区家族性乳腺癌的BRCA1基因突变率为7.7%,低于国外和国内其它地区;BRCA基因突变携带者家系中成员具有较高的发病风险.     

中国乳腺癌家族BRCA1突变分析

为了探讨中国乳腺癌家族中BRCAl基因突变情况,我们收集了15个乳腺癌家系,共41个对象,其中23例为乳腺癌患者,采用聚合酶链反应-单链构像多态性分析(PCR-SSCP)、直接DNA测序法对BRCA1编码基因进行了全序列分析。结果发现在15个家系中有4例(3种)基因突变,突变比例为26.7％(4/15)。其中一例2228insC为插入突变,致编码子711处蛋白截短;另3例(2种)突变为1884A→T和3232 A→G,分别引起单个氨基酸改变。我们认为BRCA1为家族性乳腺癌的遗传基因;在BRCA1以外还存在其他的乳腺癌易感基因。     

BRCA1基因的功能及其上游调控序列结构功能特征

乳腺癌易感基因1(BRCA1)是一种与家族性乳腺癌、家族性卵巢癌密切相关的抑癌基因.但其在散发性乳腺癌中尚未见突变的报道,而在散发性乳腺癌中其表达下降,说明其转录调控异常可能参与散发性乳腺癌的发生.本文拟对BRCA1功能及上游调控区结构功能特征作一综述.     

DBC2基因突变与上海地区早发性乳腺癌相关性的研究

目的:检测上海地区早发性乳腺癌患者DBC2基因启动子及第7外显子突变情况,探讨DBC2基因突变与早发性乳腺癌发病风险的关系.方法:提取45例家族史阴性的早发性乳腺癌患者和36名健康志愿者外周血基因组DNA,对DBC2基因启动子、第7外显子及其侧翼部分内舍子序列进行PCR扩增,通过直接测序法鉴定DNA突变位点.结果:研究组和对照组均未发现启动子或第7外显子突变;在第7内舍子发现IVS7+53C>G突变23例,研究组和对照组DNA的突变率分别为26.67%(12/45)和30.56%(11/36),两者差异无统计学意义,P>0.05.IVS7+53C>G突变患者平均发病年龄为38.33岁,比IVS7+53野生型患者大3.64岁,两者差异有统计学意义,P<0.05.结论:DBC2基因启动子及第7外显子突变可能在上海地区人群中不常见,与早发性乳腺癌发病风险无关.IVS7+53C>G突变是中国人群一种常见多态性,与早发性乳腺癌发病风险关系尚待进一步研究.     

Germ line BRCA1 and BRCA2 gene mutations in Turkish breast cancer patients

Germ line BRCA1 and/or BRCA2 mutations were screened in 50 Turkish breast and/or ovarian cancer patients composed of hereditary, familial, early onset and male cancer groups. Genomic DNA samples were tested by heteroduplex analysis and DNA sequencing. Two truncating BRCA2 mutations, one novel (6880 insG) and one previously reported (3034 delAAAC), were found in two out of six (33%) hereditary breast and/or ovarian cancer patients. A novel truncating (1200 insA) and a missense (2080A-->G) BRCA1 mutation was found in two of 27 (7%) individuals in the early onset group. A total of four (8%) disease-causing mutations in 50 breast cancer patients were identified in BRCA1 and BRCA2 genes. In addition, five BRCA1 sequence variants have been identified in 23 patients. These results indicate that BRCA1 and BRCA2 genes are involved in some, but not all, forms of hereditary predisposition to breast cancer in the Turkish population.     

Frequency of BRCA1 and BRCA2 germline mutations in Japanese breast cancer families

The purpose of this investigation is to study the frequency of BRCA1 and BRCA2 germline mutations in Japanese breast cancer families. Mutation analysis of BRCA1 and BRCA2 by SSCP was conducted on the 113 breast cancer patients (probands) with at least 1 breast cancer (site-specific breast cancer families, n = 101) or 1 ovarian cancer (breast/ovarian cancer families, n = 12) patient in their first-degree relatives. Fifteen deleterious mutations (13.3%), including 8 nonsense and 7 frameshift mutations, were identified in BRCA1, and 21 deleterious mutations (18.6%), including 8 nonsense, 12 frameshift and 1 splice-site mutations, were identified in BRCA2. In site-specific breast cancer families, mutation frequency of BRCA1 or BRCA2 was high in families with 3 or more breast cancer patients (36%, 9/25), early onset (40 < or = years old) breast cancer patients (38%, 19/50) or bilateral breast cancer patients (40%, 6/15). In breast/ovarian cancer families, mutations of BRCA1 (58.3%, n = 7), but not BRCA2 (0%, n = 0), were observed. BRCA1 codon 63 (TTA to TAA) nonsense mutation and BRCA2 frameshift mutation (5802 del AATT) were observed in 4 and 7 independent families, respectively. Haplotype analysis has suggested that carriers of each of these mutations have common ancestors. These results demonstrate that family profiles are important determinants of risk for carrying a BRCA1 or BRCA2 mutation and that cumulative frequency of BRCA1 and BRCA2 mutations in Japanese breast cancer families (31.9%) is within the range observed in Caucasian breast cancer families. Presence of Japanese founder mutations has also been suggested.     

Germline BRCA1 mutations in Iranian women with breast cancer

BRCA1 is known as a familial early onset breast cancer gene located in the long arm of chromosome 17. Alterations in this gene have been reported in different populations, some of which are population-specific mutations showing a founder effect. In this study, which is the first report on the genetic testing of Iranian women, exon-2 of the BRCA1 gene was sequenced in 80 Iranian breast cancer patients and none of the patients showed the 185del AG mutation or any changes in the sequences of this exon. Among this population, 22 patients having one or more of any kind of tumor in their first-degree relatives were selected and their entire BRCA1 gene coding region was sequenced by direct PCR-sequencing. A novel point mutation in exon-16, with unknown significance, was observed among the breast cancer patients and control subjects. This A/G mutation caused the substitution of Glutamine 1612 with Glycine, with an allele frequency of 38.6 and 52.8% in patients and controls, respectively. In addition, a point mutation in exon-15 and eight other polymorphic alterations were detected which have been reported previously. Three of these polymorphic sites were placed in the intronic part of the gene. To understand the significance of the contribution of the BRCA1 gene in the breast cancer among Iranian, further investigations are needed.     

Frequency of 5382insC mutation of BRCA1 gene among breast cancer patients: an experience from Eastern India

The incidence of breast cancer in India is on the rise and is rapidly becoming the number one cancer in females pushing the cervical cancer to the second position. The mutations in two breast cancer susceptibility genes, BRCA1 and BRCA2, are frequently associated with familial breast cancer. The main objective of the study was to determine the frequency of the mutation 5382insC in BRCA1 of eastern Indian breast cancer patients and also study the hormonal receptor status and histopathology of the patients. Altogether 92 patients affected with breast cancer were included in this study. ARMS-PCR based amplification was used to detect the presence of mutation. The mutations were considered only after pedigree analysis. Out of 92 patients (age range: 20–77 years) with family history (57 individuals) and without family history (35 individuals) were screened. Fifty controls have been systematically investigated. Seven patients and two family members were found to be carriers of 5382insC mutation in BRCA1 gene. We have found 42.64 % ER^?/PR^? cancer and 20.58 % triple negative cancer. Invasive ductal carcinoma is the most common histology among the investigated individuals. The presented data confirm a noticeable contribution of BRCA1 5382insC mutation in BC development in Eastern India, which may justify an extended BRCA1 5382insC testing within this patient population. We found HER-2/neu negativity and BRCA1 positivity associated with familial breast cancer. From the hospital’s patient history, it was revealed that the age of menarche plays an important role in development of breast cancer.     

BRCA1 germline mutations and tumor characteristics in Chinese women with familial or early-onset breast cancer

The data related to BRCA1 germline mutation in Chinese women with familial breast cancer is increasing. However, little is known the frequency of BRCA1 mutations in Chinese women with familial or early-onset breast cancer from Northern China, and few studies are available to investigate the clinicopathological characteristics of BRCA1 tumors in Chinese women. In this study, we detected germline mutations in BRCA1 in a cohort of 139 breast cancer patients who either have a family history of breast cancer (n = 68) or whose tumors are diagnosed at or before the age of 35 (n = 71) from Northern China. A total of 6 deleterious BRCA1 mutations were identified in this cohort, 4 of which (5587-1 del8, 3887 del AG, IVS21 + 1delG, and 2129 ins TG) are novel and one mutation (3478del5) detected in this study was only reported in Chinese population. The frequency of BRCA1 mutations in women with familial or early-onset breast cancer was 5.9% (4/68) or 2.8% (2/71) in this cohort, respectively; but the mutations were detected in 4 of 16(25.0%) familial breast cancer patients whose tumors were diagnosed before the age of 40. Moreover, BRCA1 mutation tumors tended to be high histological grade, and to be negative for ER, PgR, and Her-2 compared with tumors without BRCA1 mutations. Our study suggests that Chinese women with a family history of breast cancer whose tumors are diagnosed before age of 40 would be a suitable candidate for BRCA1 testing; and BRCA1 tumors in Chinese women exhibit an aggressive phenotype. W. Chen and K. Pan contributed equally to this study.     

家族性乳腺癌家系成员乳腺癌易感基因突变的研究

目的研究河北省地区家族性乳腺癌家系中的患者及健康一级亲属乳腺癌易感基因1（BRCAl）和乳腺癌易感基因2（BRCA2）突变位点及携带情况。方法研究对象为2002年6月至2008年5月河北医科大学第四医院接诊的乳腺癌患者及其亲属,分别来自12个独立的汉族家族性乳腺癌家系,该家系中有2个及2个以上一级或二级亲属乳腺癌患病史,研究病例包括13例患者及46例健康一级亲属,共59例样本。由外周血提取基因组DNA,采用聚合酶链反应一单链构象多态性分析（PCR—SSCP）和基因测序技术对国内外报告中常见的4个BRCAl／BRCA2突变热点区域（BRCAl：外显子2、11、20;BRCA2外显子11）进行检测。结果发现1个BRCAl突变位点（4193insA）和1个BRCA2突变位点（5329insT）,全部为移码突变;发现4个变异位点（BRCAl：4165T〉A、287G〉C,BRCA2：6251G〉T、5416C〉A）,4193insA、5329insT、287G〉C携带者的家系中均有3例乳腺癌患者。结论BRCAl（4193insA）、BRCA2（5329insT）以及BRCAl：4165T〉A、287G〉C和BRCA2：6251G〉T、5416C〉A可能是河北省家族性乳腺癌相关性突变位点,其携带者家系中乳腺癌发病率明显升高,建议对其一级亲属密切随访或尽早进行手术或药物干预。     

Contribution of inherited mutations in the BRCA2-interacting protein PALB2 to familial breast cancer

Inherited mutations in the BRCA2-interacting protein PALB2 are known to be associated with increased risks of developing breast cancer. To evaluate the contribution of PALB2 to familial breast cancer in the United States, we sequenced the coding sequences and flanking regulatory regions of the gene from constitutional genomic DNA of 1,144 familial breast cancer patients with wild-type sequences at BRCA1 and BRCA2. Overall, 3.4% (33/972) of patients not selected by ancestry and 0% (0/172) of patients specifically of Ashkenazi Jewish ancestry were heterozygous for a nonsense, frameshift, or frameshift-associated splice mutation in PALB2. Mutations were detected in both male and female breast cancer patients. All mutations were individually rare: the 33 heterozygotes harbored 13 different mutations, 5 previously reported and 8 novel mutations. PALB2 heterozygotes were 4-fold more likely to have a male relative with breast cancer (P = 0.0003), 6-fold more likely to have a relative with pancreatic cancer (P = 0.002), and 1.3-fold more likely to have a relative with ovarian cancer (P = 0.18). Compared with their female relatives without mutations, increased risk of developing breast cancer for female PALB2 heterozygotes was 2.3-fold (95% CI: 1.5-4.2) by age 55 and 3.4-fold (95% CI: 2.4-5.9) by age 85. Loss of the wild-type PALB2 allele was observed in laser-dissected tumor specimens from heterozygous patients. Given this mutation prevalence and risk, consideration might be given to clinical testing of PALB2 by complete genomic sequencing for familial breast cancer patients with wild-type sequences at BRCA1 and BRCA2.     

BRCA1 andBRCA2 germline mutations in Japanese with hereditary breast cancer families

We examined germline mutations inBRCA1 andBRCA2 in 23 Japanese breast cancer families, using PCR-SSCP analysis. The same nonsense mutation (exon 5, Leu63ter) ofBRCA1 was detected in two different families. Three different mutations resulting in a truncatedBRCA2 protein (exon 9, 20, 24) were detected in three different families, including one male case of breast cancer. One base substitution mutation inBRCA2, A10462G, was detected in the other two families. Although the mean age of onset for breast cancer in families with theBRCA1- mutation was 50 years, the age of onset in families with theBRCA2-mutation was from 28 to 43 years. Among the 23 families examined, two families had members with ovarian cancers, three had members with prostate cancers, and one had a pancreatic cancer. However, none of these families was positive for theBRCA1 orBRCA2 mutation. Histopathologically, we observed a prevalence of histological grade 3 inBRCA2-associated familial breast cancers, because of nuclear atypia, structural atypia and mitotic activity. It is suggested thatBRCA2 may play a more important role thanBRCA1 in Japanese familial breast cancers, and these mutations are related to the aggressive nature and highly proliferative activity of the tumors.     

Novel germline mutations in breast cancer susceptibility genes BRCA1, BRCA2 and p53 gene in breast cancer patients from India

Mutations in breast cancer susceptibility genes, BRCA1 and BRCA2 account for more than 80% of hereditary breast and ovarian cancers. p53 tumor suppressor gene that controls cellular growth and differentiation is also known to be mutated in more than 50% of human cancers including breast cancer. We have carried out a study on BRCA1 and BRCA2 along with p53 gene mutations in both sporadic as well as familial breast cancer patients from India where breast cancer is fast emerging as a major cancer among premenopausal urban women. We examined 124 untreated primary breast cancer patients comprising 100 sporadic and 24 familial cases including 56 age-matched healthy controls for the presence of BRCA1, BRCA2 and the p53 gene mutations using PCR-SSCP and direct nucleotide sequencing. Certain frequently mutated exons such as 2, 5, 11, 13 and 20 of BRCA1, exons 2, 9, 11 (for 6174delT), 18 and 20 of BRCA2 and 4–9 exons of p53 gene were analyzed in sporadic breast cancer while all 22 coding exons of BRCA1 including its flanking intronic regions along with above mentioned exons of BRCA2 and p53 gene were analyzed in familial breast cancer patients. We identified six patients (25%) with BRCA1 mutation of which three were found to be of novel type one in exon 16 (4956insG) and two in exon 7 (Lys110Thr) (Ser114Pro) out of 24 familial breast cancer patients studied from two different geographic regions/populations of India. Two sisters from a single family (12.5%) out of eight families from Goa with Portuguese colonial origin showed presence of founder Ashkenazi Jewish BRCA1 mutation (185delAG) along with (IVS7 561–34T>C; IVS18 527166G>A). While from New Delhi, four (25%) of 16 breast cancer families showed BRCA1 mutations; a frame shift protein truncating (4956insG), a transition nonsense (Gln1395Stop) and two amino acid substitutions (Lys110Thr) and (Ser114Pro). Only one (4%) p53 mutation (Val97Ile) in its exon 4 along with BRCA1 mutation (4956insG) could be detected. No major sequence variation in BRCA2 gene was observed except for G203A at 5 UTR of exon 2, a common population polymorphism in two Goan patients who also showed silent nucleotide change for amino acid serine at codon 1436 of BRCA1 gene. None of the 100 sporadic breast cancer patients revealed any protein truncating or deleterious BRCA1 or BRCA2 gene mutation. Interestingly, three (3%) p53 mutations in its exon 5 were detected in sporadic breast cancer patients. Although three novel BRCA1 mutations including a founder Ashkenazi Jewish BRCA1 mutation were recorded in Indian women with familial breast cancer, the overall prevalence of BRCA gene mutations in Indian women with a family history of breast cancer appears to be low.     

High prevalence of BRCA1 and BRCA2 mutations in unselected Nigerian breast cancer patients

Inherited mutations in the BRCA1 and BRCA2 genes are the strongest genetic predictors of breast cancer and are the primary causes of familial breast/ovarian cancer syndrome. The frequency, spectrum and penetrance of mutant BRCA1/BRCA2 alleles have been determined for several populations, but little information is available for populations of African ancestry, who suffer a disproportionate burden of early onset breast cancer. We have performed complete sequence analysis of all BRCA1 and BRCA2 exons and intron-exon boundaries for 434 Nigerian breast cancer patients from the University College Hospital in Ibadan, Nigeria. In contrast to previous suggestions that BRCA1/BRCA2 mutation frequencies are low or undetectable in African American populations, we find that Nigerian breast cancer patients have an exceptionally high frequency of BRCA1 and BRCA2 mutations (7.1 and 3.9%, respectively). Sixteen different BRCA1 mutations were detected, seven of which have never been reported previously, while thirteen different BRCA2 mutations were seen, six of which were previously unreported. Thus, our data support enrichment for genetic risk factors in this relatively young cohort. To improve breast cancer outcomes, we suggest that family-based models of risk assessment and genetic counseling coupled with interventions to reduce breast cancer risk should be broadly disseminated in Nigeria and other underserved and understudied populations.