Nuclear morphometric features in benign breast tissue and risk of subsequent breast cancer

Germ-line mutations in BRCA1 and BRCA2 are responsible for about 30–60% of the hereditary breast and ovarian cancer (HBOC). A large number of point mutations have been described in both genes. However, large deletions and duplications that disrupt one or more exons are overlooked by point mutation detection approaches. Over the past years several rearrangements have been identified in BRCA1, while few studies have been designed to screen this type of mutations in BRCA2. Our aim was to estimate the prevalence of large genomic rearrangements in the BRCA2 gene in Spanish breast/ovarian cancer families. The multiplex ligation-dependent probe amplification (MLPA) was employed to search gross deletions or duplications of BRCA2 in 335 Spanish moderate to high-risk breast/ovarian cancer families previously screened negative for point mutations by conventional methods. Four different and novel large genomic alterations were consistently identified by MLPA in five families, respectively: deletions of exon 2, exons 10–12 and exons 15–16 and duplication of exon 20 (in two families). RT-PCR experiments confirmed the deletion of exons 15–16. All patients harbouring a genomic rearrangement were members of high-risk families, with three or more breast/ovarian cancer cases or the presence of breast cancer in males. We provide evidence that the BRCA2 rearrangements seem to account for a relatively small proportion of familial breast cancer cases in Spanish population. The screening for these alterations as part of the comprehensive genetic testing can be recommended, especially in multiple case breast/ovarian families and families with male breast cancer cases.     

BRCA2 germ-line mutations in Spanish male breast cancer patients

Background:Mutations in the BRCA2 gene account for the majorityof the families with male and female breast cancer cases, and a number ofBRCA2 mutations have been reported in males with breast cancer. The aim ofthis study was to characterise BRCA2 germ-line mutations in Spanish malebreast cancer patients. Patients and methods:We screened DNA from 11 affected men and 6women with breast cancer (BC) who had an affected male relative (father orbrother). Exons 2–9 and 12–27 were screened by SSCP, and exons 10and 11 were screened by PTT. PCR products with a variant band were sequenced. Results:Three BRCA2 frameshift mutations were identified(17.6%): the 3374delA in codon 1049 (exon 11), 6857delAA in codon 2010(exon 11), and 9254delATCAT in codon 3009 (exon 23). These mutations werepresent in patients with affected first-degree relatives (3 of 9, 33%).The proportion of male patients with a family history of BC in at least onefirst-degree relative was 53%. Conclusions:There is an association between BRCA2 mutations andmale breast cancer, especially in those with a family history of BC. The highprevalence of BRCA2 mutations among males should be considered when estimatingrisk for female relatives. All new male cases of BC should be regarded asbeing possibly inherited and should be fully investigated.     

家族性和早发性乳腺癌BRCA1基因突变分析

目的 分析中国黑龙江省家族性和早发性乳腺癌中BRCA1基因的突变情况。方法 以黑龙江地区的92例家族性和早发性乳腺癌(发病年龄≤35岁)为研究对象。由静脉血提取基因组DNA,对BRCA1基因的全部编码序列(除外1,4号外显子)进行扩增。由聚丙烯酰胺凝胶电泳分析(SSCP)进行突变的初筛,之后进行DNA直接测序证实。结果 在92例乳腺癌患者中发现有5种致病性突变,其中3种为新发现的突变,发现的已报道的2种突变均为无义突变。结论 在中国黑龙江人群中,BRCA1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3个突变位点可能是中国人群中的特有突变;黑龙江地区BRCA1在家族性乳腺癌中突变率明显低于国内外报道,但其中的移码突变3712insG分别在3个患者中检出,提示有可能成为该地区的基础突变。     

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.     

BRCA1 Gene Mutations in Chinese Families with Breast Cancer

OBJECTIVE To investigate the frequency of BRCA1 gene mutations in breast cancer families in China.METHODS Genomic DNA was obtained by conventional techniques from the peripheral blood mononuclear cells collected from 94 persons derived from 45 breast cancer families. All participants gave written informed consent. The mutations in the BRCA1 gene were detected by the polymerase chain reaction and single stranded conformation polymorphism(PCR-SSCP). Then , the samples of interest were sent for direct DNA sequencing.RESULTS No mutation sites were found in exon 2 or 20 by DNA sequencing.Eight sites were found in exon 11 such as 2201C>T (Ser694Ser),3232A>G(Glu 1038Gly), 2201C >A/G (Ser694Arg), 2731C >T (Pro871Leu),2086A >T(Asn591lle) and three sites of 1584G>T (Glu424Stop). Three mutation sites were found in exon 16 which included 5106A >G (Met1663Val),5208delT(Stop 1639) and 4956A>G (Ser 1613Gly).CONCLUSION These mutation sites may be related to breast cancer, but more investigation is needed to determine whether the mutation sites are hot spots of mutations in Chinese familial breast cancer patients.     

Identification of a novel BRCA1 large genomic rearrangement in a Spanish breast/ovarian cancer family

Background Alterations in BRCA1 gene are responsible for the majority of hereditary breast and/or ovarian cancers. However, the frequency of detected germline mutations is lower than expected by linkage analysis. Standard PCR-based screening methods are mainly used for detecting mutations, but the large genomic rearrangements are commonly overlooked. The purpose of this study was to confirm and characterize a novel deletion identified in BRCA1 gene which has not yet been reported to date. Methods Multiplex ligation-dependent probe amplification was used to analyze BRCA1 rearrangements in 255 unrelated index patients with familial breast and/or ovarian cancer negative for BRCA1/BRCA2 mutations studied in Program of Genetic Counselling on Cancer of Valencia Community (Spain). The breakpoints of detected novel rearrangement were characterized by sequencing. Results and discussion Five different rearrangements in the BRCA1 gene were identified in five unrelated index patients out of the 225 (2%). We found four large genomic rearrangements already described consisting in a 1A/1B and 2 deletion; deletion of exons 5–7; deletion of exons 8–13; exon 20 deletion. Additionally, we found the novel g.8097_22733del14637 deletion that encompasses exons 3–5. This deletion affects the RING domain of the BRCA1 protein and it is suggestive of having a negative impact on its function. Conclusion The new mutation here reported broadens the mutational spectrum of large rearrangements. Furthermore, the five large rearrangements found in patients non-carriers of BRCA1/BRCA2 mutations reinforce the need of studying BRCA1 large genomic rearrangements in genetic counselling programs.     

Primary node negative breast cancer in BRCA1 mutation carriers has a poor outcome

Background:The association between BRCA1 germ-linemutations and breast cancer prognosis is controversial. A historical cohortstudy was designed to determine the prognosis for women with axillary lymphnode negative hereditary breast cancer. Patients and methods:We tested pathology blocks from 118Ashkenazi Jewish women with axillary lymph node negative breast cancer for thepresence of the two common BRCA1 founder mutations, 185delAG and5382insC. Patients were followed up for a median of 76 months. SomaticTP53mutations were screened for by immunohistochemistry, and directsequencing was performed in the BRCA1-positive tumours. Results:Sixteen breast cancer blocks (13.6%) carried aBRCA1 mutation. Young age of onset, high nuclear grade, negativeestrogen receptor status and over-expression of p53 were highly associatedwith BRCA1-positive status (P-values all <0.01).BRCA1 mutation carriers had a higher mortality than non-carriers(five-year overall survival, 50% and 89.6%, respectively,P = 0.0001). Young age of onset, estrogen receptor negative status,nuclear grade 3, and over-expression of p53 also predicted a poor outcome. Coxmultivariate analyses showed that only germ-line BRCA1 mutationstatus was an independent prognostic factor for overall survival (P= 0.01). Among nuclear grade 3 tumours, the BRCA1 mutation carrierstatus was a significant prognostic factor of death (risk ratio 5.8,95% confidence interval: 1.5–22, P = 0.009). Sequencingof BRCA1-related breast cancers revealed one TP53missensemutation not previously reported in breast cancer. Conclusions:Using a historical cohort approach, we haveidentified BRCA1 mutation status as an independent prognostic factorfor node negative breast cancer among the Ashkenazi Jewish women. Thosemanaging women carrying a BRCA1 mutation may need take these findingsinto consideration. Additionally, our preliminary results, taken together withthe work of others suggest a different carcinogenic pathway inBRCA1-related breast cancer, compared to non-hereditary cases.     

High detection rate for BRCA2 mutations in male breast cancer families from North West England

33 families with a history of male breast cancer aged 60 or less or with a family history of male and female breast cancer were screened for the presence of BRCA2 mutations. 12 pathogenic BRCA2 mutations were identified (36%) in samples from an affected family member. All mutations segregated with disease where it was possible to check. Of the 14 families fulfilling BCLC criteria, 9 (64%) had mutations whilst only 3/16 (19%) of male breast cancer patients with less significant female breast cancer family history having a mutation. All 3 families with ovarian cancer and 3 families with multiple male breast cancer cases had BRCA2 mutations. These data are a further guide to how to prioritise samples for BRCA2 mutation analysis.     

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。     

Mutation screening of BRCA1 using PTT and LOH analysis at 17q21 in breast carcinomas from familial and non-familial cases

Germline mutations in the BRCA1 gene predispose to breast and ovarian cancer. An estimated 45% of families with multiple breast cancer cases and more than 80% of breast-ovarian cancer families are linked to BRCA1. Mutation analyses by collaborative laboratories have revealed around 460 distinct BRCA1 sequence alterations, mostly germline mutations from familial cases. The majority of these alterations were nonsense and frame-shift mutations. In the present study, breast tumors of both sporadic and familial origin were investigated for allelic imbalance (AI) at the BRCA1 locus. AI was observed in 52% of the sporadic cases and in 17% of the familial cases. Furthermore, 104 breast carcinomas from patients with sporadic disease and 77 patients with positive family histories of breast and/or ovarian cancer were examined for translation-terminating mutations in exon 11 of the BRCA1 gene using the protein truncation test (PTT). No somatic mutations were detected in any of the tumors analysed, and only one BRCA1 mutation carrier was found among the familial cases. The result of this study gives no indication that truncating somatic mutations in exon 11 of BRCA1 play a major role in the tumorigenesis of the breast. Furthermore, the frequency of such mutation carriers in breast cancer populations with weak family histories of breast and/or ovarian cancer seems to be low.     

The prevalence of BRCA1 and BRCA2 germline mutations in high-risk breast cancer patients of Chinese Han nationality: two recurrent mutations were identified

To have an overview of the role of BRCA1 and BRCA2 genes among Chinese high-risk breast cancer patients, we analyzed 489 such high-risk breast cancer patients from four breast disease clinical centers in China, by using PCR-DHPLC or SSCP-DNA sequencing analysis. Allelotype analysis was done at five short tandem repeat (STR) markers in or adjacent to BRCA1 on the recurrent mutation carriers. For those analyzed both genes, 8.7% of early-onset breast cancer cases and 12.9% of familial breast cancer cases had a BRCA1 or BRCA2 mutation, as compared with the 26.1% of cases with both early-onset breast cancer and affected relatives. For those reporting malignancy family history other than breast/ovarian cancer, the prevalence of BRCA1/2 mutation is about 20.5%, and it was significantly higher than the patients only with family history of breast/ovarian cancer (P = 0.02). The family history of ovarian cancer (26.7% vs. 11.9%) and stomach cancer (23.8% vs. 11.8%) doubled the incidence of BRCA1/2, but the difference did not reach the statistical significance. Two recurrent mutations in BRCA1, 1100delAT and 5589del8, were identified. The recurrent mutations account for 34.8% BRCA1 mutations in our series. Similar allelotypes were detected in most STR status for those harboring the same mutations. The BRCA1 associated tumors were more likely to exhibit a high tumor grade, negative C-erbB-2/neu status and triple negative (ER, PgR and C-erbB-2/neu negative) status (P < 0.05). We recommended the BRCA1 and BRCA2 genetic analysis could be done for high-risk breast cancer patient in Chinese population, especially for those with both early-onset breast cancer and affected relatives. There may be some degree of shared ancestry for the two recurrent BRCA1 mutations in Chinese. Wen-Feng Li and Zhen Hu have contributed equally to this work.     

BRCA1 and BRCA2 germline mutational spectrum and evidence for genetic anticipation in Portuguese breast/ovarian cancer families

We present the first characterisation of the mutational spectrum of the entire coding sequences and exon–intron boundaries of the BRCA1 and BRCA2 genes as well as large BRCA1 rearrangements in Portuguese families with inherited predisposition to breast/ovarian cancer. Of the 100 probands studied, pathogenic mutations were identified in 22 (24.7%) of 89 breast and/or ovarian cancer families with more than one affected member (15 in BRCA1 and seven in BRCA2), but in none of the 11 patients without family history of cancer. One (6.7%) of the BRCA1 mutations is a large deletion involving exons 11–15. Seven pathogenic point mutations are novel: 2088C>T, 2156delinsCC, and 4255_4256delCT in BRCA1 and 4608_4609delTT, 5036delA, 5583_5584insT, and 8923C>T in BRCA2. The novel 2156delinsCC was identified in three probands from different families and probably represents a founder mutation in our population. We also found a previously reported 3450_3453del4 mutation in three unrelated patients. In addition to the 22 pathogenic mutations, we identified 19 missense mutations of uncertain pathogenic significance, three of them (5241G>C in BRCA1 and IVS6+13C>T and 3731T>C in BRCA2) previously undescribed. The percentage of cases with truncating mutations in BRCA1 and BRCA2 was higher in breast/ovarian cancer (37.0%, mostly BRCA1) and male breast cancer (40%, all BRCA2) families than in families with only female breast cancer (17.5%). Interestingly, we found evidence for genetic anticipation regarding age at diagnosis of both breast and ovarian cancer in those families presenting affected members in more than one generation. These findings should be taken into consideration while planning screening and prophylactic measures in families with inherited predisposition to breast and ovarian cancer.     

Greek BRCA1 and BRCA2 mutation spectrum: two BRCA1 mutations account for half the carriers found among high-risk breast/ovarian cancer patients

127 Greek breast/ovarian cancer families were screened for germline BRCA1/2 mutations by dHPLC followed by direct sequencing. Our results indicated 16 and 5 breast/ovarian cancer families bearing deleterious mutations in the BRCA1 and BRCA2 genes, respectively. Two novel BRCA2 germline mutations (G4X and 3783del10) are reported here for the first time. Subsequent compilation of our present findings with previously reported mutation data reveals that in a total of 287 Greek breast/ovarian cancer families, 46 and 13 carry a deleterious mutation in BRCA1 and BRCA2, respectively. It should be noted that two BRCA1 mutations, 5382insC and G1738R, both located in exon 20, account for 46% of the families found to carry a mutation. Based on our mutation analysis results, we propose here a hierarchical, cost-effective BRCA1/2 mutation screening protocol for individuals of Greek ethnic origin. The suggested protocol can impact on the clinical management of breast-ovarian cancer families on a national healthcare system level. Irene Konstantopoulou and Theodore Rampias equally contributed to this work.     

Genomic analysis of inherited breast cancer among Palestinian women: Genetic heterogeneity and a founder mutation in TP53

Breast cancer among Palestinian women has lower incidence than in Europe or North America, yet is very frequently familial. We studied genetic causes of this familial clustering in a consecutive hospital‐based series of 875 Palestinian patients with invasive breast cancer, including 453 women with diagnosis by age 40, or with breast or ovarian cancer in a mother, sister, grandmother or aunt (“discovery series”); and 422 women diagnosed after age 40 and with negative family history (“older‐onset sporadic patient series”). Genomic DNA from women in the discovery series was sequenced for all known breast cancer genes, revealing a pathogenic mutation in 13% (61/453) of patients. These mutations were screened in all patients and in 300 Palestinian female controls, revealing 1.0% (4/422) carriers among older, nonfamilial patients and two carriers among controls. The mutational spectrum was highly heterogeneous, including pathogenic mutations in 11 different genes: BRCA1, BRCA2, TP53, ATM, CHEK2, BARD1, BRIP1, PALB2, MRE11A, PTEN and XRCC2. BRCA1 carriers were significantly more likely than other patients to have triple negative tumors (p = 0.03). The single most frequent mutation was TP53 p.R181C, which was significantly enriched in the discovery series compared to controls (p = 0.01) and was responsible for 15% of breast cancers among young onset or familial patients. TP53 p.R181C predisposed specifically to breast cancer with incomplete penetrance, and not to other Li‐Fraumeni cancers. Palestinian women with young onset or familial breast cancer and their families would benefit from genetic analysis and counseling.     

散发性乳腺癌患者BRCA1基因突变分析

目的 :探讨BRCA1基因突变在散发性乳腺癌发生和发展中的作用及在乳腺癌临床诊断和治疗中的应用前景。方法 :应用PCR SSCP和直接测序法检测 3 0例散发性乳腺癌和 15例正常乳腺组织中BR CA1基因外显子 2、11和 2 0的突变情况。结果 :15例正常乳腺组织在 3个外显子上都未显示电泳异常 ,3 0例乳腺癌中有 6例在外显子 2上显示电泳条带异常 ,其中 4例经测序证实有突变 ,1例在外显子 2上 ,3例在内含子拼接区。BRCA1基因突变率在初诊年龄、临床分期和肿瘤体积上差异无统计学意义 ,但与肿瘤转移密切相关。结论 :BRCA1基因突变与散发性乳腺癌的发生和发展密切相关 ,该基因突变筛查可作为一种预后指标。     

BRCA1 and BRCA2 germline mutation spectrum and frequencies in Belgian breast/ovarian cancer families

Worldwide variation in the distribution of BRCA1 and BRCA2 mutations is well recognised, and for the Belgian population no comprehensive studies about BRCA1/2 mutation spectra or frequencies have been published. We screened the complete coding region of both genes in 451 individuals from 349 Belgian families referred to a family cancer clinic and identified 49 families with a BRCA1 and 26 families with a BRCA2 mutation. Six major recurrent mutations (BRCA1 IVS5+3A>G, 2478-2479insG, E1221X and BRCA2 IVS6+1G>A, 6503-6504delTT, 9132delC) accounted for nearly 60% of all mutations identified. Besides 75 true pathogenic mutations, we identified several variants of unknown clinical significance. In combination with a family history, an early average age of female breast cancer diagnosis (P<0.001), and the presence of a relative with ovarian cancer (P<0.0001) or multiple primary breast cancers (P=0.002), increased the chance for finding a mutation. Male breast cancer was indicative of a BRCA2 mutation segregating in the family (P=0.002). Mutations in the 5'-end of BRCA1 and BRCA2 were associated with a significantly increased risk for ovarian cancer relative to the central portion of the gene. Our study suggests a role for additional breast cancer susceptibility genes in the Belgian population, since mutation detection ratios were low in high-risk breast cancer-only families as compared to breast-ovarian cancer families. Given the large proportion of recurring mutations, molecular testing can now be organised in a more cost-effective way. Our data allow optimisation of genetic counselling and disease prevention in Belgian breast/ovarian cancer families.     

Mutations of the BRCA1 and BRCA2 genes in patients with bilateral breast cancer

Mutations of the BRCA1 or BRCA2 genes have been shown to strongly predispose towards the development of contralateral breast cancer in patients from large multi-case families. In order to test the hypothesis that BRCA1 and BRCA2 mutations are more frequent in patients with bilateral breast cancer, we have investigated a hospital-based series of 75 consecutive patients with bilateral breast cancer and a comparison group of 75 patients with unilateral breast cancer, pairwise matched by age and family history, for mutations in the BRCA1 and BRCA2 genes. Five frameshift deletions (517delGT in BRCA1; 4772delA, 5946delCT, 6174delT and 8138del5 in BRCA2) were identified in patients with bilateral disease. No further mutations, apart from polymorphisms and 3 rare unclassified variants, were found after scanning the whole BRCA1 and BRCA2 coding sequence. Three pathogenic BRCA1 mutations (Cys61Gly, 3814del5, 5382insC) were identified in the group of patients with unilateral breast cancer. The frequencies of common BRCA1 and BRCA2 missense variants were not different between the 2 groups. In summary, we did not find a significantly increased prevalence of BRCA1 and BRCA2 mutations in a hospital-based cohort of German patients with bilateral breast cancer. We conclude that bilaterality of breast cancer on its own is not strongly associated with BRCA1 and BRCA2 mutations when adjusted for age and family history. The high frequency of bilateral disease in multi-case breast cancer families may be due to a familial aggregation of additional susceptibility factors modifying the penetrance of BRCA1 and BRCA2 mutations.     

Contribution of BRCA1 germ-line mutations to breast cancer in Greece: a hospital-based study of 987 unselected breast cancer cases

Background:

In most Western populations, 5–10% of all breast cancer cases can be attributed to major genetic factors such as predisposing mutations in BRCA1 and BRCA2, with early-onset cases generally considered as an indicator of genetic susceptibility. Specific BRCA1 and BRCA2 mutations or different mutation frequencies have been identified in specific populations and ethnic groups. Previous studies in Greek breast and/or ovarian cancer patients with family history have shown that four specific BRCA1 mutations, c.5266dupC, G1738R, and two large genomic rearrangements involving deletions of exons 20 and 24, have a prominent function in the population''s BRCA1 and BRCA2 mutation spectrum.

Methods:

To estimate the frequency of the above mutations in unselected Greek breast cancer women, we screened 987 unselected cases independently of their family history, collected from major Greek hospitals.RESULTS: Of the 987 patients, 26 (2.6%) were found to carry one of the above mutations in the BRCA1 gene: 13 carried the c.5266dupC mutation (1.3%), 6 carried the exon 24 deletion (0.6%), 3 carried the exon 20 deletion (0.3%), and 4 carried the G1738R mutation (0.4%). Among 140 patients with early-onset breast cancer (<40 years), 14 carried one of the four mutations (10.0%).

Conclusion:

These results suggest that a low-cost genetic screening for only the four prominent BRCA1 mutations may be advisable to all early-onset breast cancer patients of Greek origin.     

Association of the C677T polymorphism in the MTHFR gene with breast and/or ovarian cancer risk in Jewish women

The C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with reduced enzyme activity, hyperhomocysteinaemia and increased risk for atherosclerosis in homozygotes. We examined the frequency of this mutation and its association with disease pattern in 491 Jewish women with either sporadic (n=355; 72%) or hereditary (n=136; 28%) breast and/or ovarian cancer and in 69 asymptomatic BRCA1/2 mutation carriers, genotyped for the three predominant Jewish founder BRCA1/2 mutations (185delAG, 5382insC and 6174delT). 677T homozygotes were equally distributed among women with sporadic breast and/or ovarian cancer (71/355; 20.0%) and among BRCA1/2 mutation carriers (43/205; 21.0%) (P=non-significant). 677T homozygotes were equally distributed among women diagnosed with breast cancer prior to (22/122; 18.0%) and after 42 years of age (42/243; 17.3%). Among BRCA1/2 carriers, the rate of 677T homozygotes in manifesting cancer (32/136; 23.5%) and asymptomatic individuals (11/69; 15.9%) was not significantly different. The rate of 677T homozygotes (24/72; 33.3%) was higher (P=0.0026) among women with bilateral breast cancer and those with both breast and ovarian carcinoma than among those with unilateral breast cancer (64/365; 17.5%). Differences in morbidity (one versus multiple breast/ovarian tumours) are mainly attributed to 677T homozygosity and partly to BRCA1/2 mutations. Confirmation of these data, namely, that the 677T allele is significantly more common in cases of bilateral breast cancer or combined breast and ovarian cancer would have important clinical implications.     

BRCA1 and BRCA2 mutations in Turkish breast/ovarian families and young breast cancer patients

To date, BRCA1 and BRCA2 mutations in breast and/or ovarian patients have not been characterized in the Turkish population. We investigated the presence of BRCA mutations in 53 individuals with a personal and family history of breast and/or ovarian cancer, and 52 individuals with a personal history of breast cancer diagnosed below age 50 without additional family history. We have identified 11 mutations (nine BRCA1 and two BRCA2) using combined techniques involving protein truncation test, direct sequencing and heteroduplex analysis. We found eight out of 53 patients (15.1%) with a family history to carry BRCA gene mutations (seven BRCA1 and one BRCA2). Of these, four were found in 43 families presenting only breast cancer histories, and four were found in families presenting ovarian cancer with or without breast cancer. We also demonstrated two BRCA1 and one BRCA2 mutations in three out of 52 (5.8%) early-onset breast cancer cases without additional family history. Three of nine BRCA1 and both BRCA2 mutations detected in this study were not reported previously. These mutations may be specific to the Turkish population. The BRCA1 5382insC mutation, specific to Ashkenazi and Russian populations, was found twice in our study group, representing a possible founder mutation in the Turkish population.