Identification of Germline BRCA1 Mutations among Breast Cancer Families in Northeastern Iran

Background: The purpose of this study was to evaluate the prevalence of BRCA1 (MIM: 113705) foundermutations in familial breast cancer (BC) patients with high risks in Iran. BRCA1 is among the cancer susceptibilitygenes best known for high penetrance mutations. BRCA1 genotyping is now used to determine patient counseling,management decisions, and prognosis of this syndrome. Materials and Method: Thirty nine patients with clinicalBC and 29 high risk healthy women, related to the patients, participated in the study. DNA from blood sampleswas extracted and analyzed by PCR and SSCP methods in order to find 185delAG and 5382insC foundermutations. In addition, a 251bp fragment of BRCA1’s exon 11 was amplified and analyzed for determination ofnew mutations. Results: The data indicated the presence of 185delAG and 5382insC founder mutations in bothgroups studied. Two out of 39 BC patients (5.1%) and one out of 29 relatives (3.4%) were suspected to be carriersof 185delAG mutations. However, we found only one patient (2.6%) to be a carrier of a 5382insC mutation. Also,2 women (5.1%) of the patient group and 3 n (10.3%) of relatives group were identified as carriers of unclarifiedmutations in the 251bp fragment of the BRCA1 gene. The carriers of BRCA1 founder mutations have a highlifetime risk of breast cancer. Conclusions: Therefore, these data are useful in counseling of individuals with asignificant family history of breast cancer.     

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.     

Prevalence of founder BRCA1 and BRCA2 mutations among breast and ovarian cancer patients in Hungary

We have investigated the impact of BRCA1 and BRCA2 mutations that were frequently identified among Hungarian high-risk breast-ovarian cancer families (Ramus et al., 1997b, AJHG), on the development of breast and ovarian cancer in the general Hungarian population. The prevalence of 3 BRCA1 mutations (185delAG, 300T-->G and 5382insC) and 2 BRCA2 mutations (6174delT and 9326insA) was evaluated in a hospital-based consecutive series of 500 female breast cancer patients and 90 ovarian cancer patients, not selected for age at diagnosis or family history of cancer, as well as in 350 controls. Among breast cancer patients, 3.6% (18/500) carried a founder mutation: 9 BRCA1 300T-->G, 7 BRCA1 5382insC, 1 BRCA1 185delAG and 1 BRCA2 9326insA. Among ovarian cancer patients, 11% (10/90) carried a founder mutation: 5 BRCA1 185delAG, 4 BRCA1 300T-->G and 1 BRCA1 5382insC. One control carried a mutation, BRCA1 5382insC. Inherited breast cancer was more frequent among women with younger age at diagnosis: 6.1% of women younger than age 50 but 2.4% of women diagnosed at age 50 or older carried one of the founder mutations. There was no association between mutation status and age at diagnosis of ovarian cancer. Three of 23 medullary breast cancers were inherited (p = 0.038). Carrier status was also associated with a non-significant trend toward advanced tumor stage at diagnosis. These mutations could be evaluated among all ovarian cancer patients and breast cancer patients younger than age 60 and of Hungarian ancestry.     

High incidence of BRCA1–2 germline mutations, previous breast cancer and familial cancer history in Jewish patients with uterine serous papillary carcinoma

OBJECTIVE: To test the carrier status of the three germline founder mutations in Jewish patients with uterine serous papillary carcinoma (USPC) and to evaluate its association to their personal and familial cancer records. METHODS: Retrospective analysis of histologically confirmed USPC Jewish patients diagnosed between April 1, 1997 and December 31, 2003. All cases were genetically tested for the three BRCA1-2 founder germline mutations (185delAG and 5382insC in BRCA1 and 6174delT in BRCA2). The analysis was performed on genomic DNA extracted from whole blood or paraffin embedded normal tissue of these patients, employing PCR amplification of target sequences and differential digestion with restriction enzymes. The carrier frequency was compared to the known population frequency of these mutations. RESULTS: The study group comprised 22 Jewish patients with USPC diagnosed within this timeframe. The mean age was 71.8 years (range 56-79). FIGO surgical stage distribution revealed 59% at stages III-IV. Seven USPC patients (32%) with a previous diagnosis of breast cancer were identified. Familial cancer history was recorded in 23% of the patients (four with breast cancer and one with ovarian cancer). DNA analysis revealed six BRCA1-2 germline mutation carriers (27%) as follows: three with BRCA2-6174delT, two with BRCA1-185delAG, and one with BRCA1-5382insC mutation. Three of the carriers had a previous diagnosis of breast cancer. Four carriers had familial cancer history in first-degree relative (three with breast cancer and one with ovarian cancer). CONCLUSIONS: The high rate of BRCA germline mutations in USPC patients observed in the present study, coupled with the strong personal and familial cancer history as well as the histological and clinical resemblance to the ovarian cancer, may indicate that USPC is a part or an expression of the hereditary breast-ovarian cancer syndrome. This option may have implications in our clinical recommendations for non-affected BRCA1-2 carriers.     

High frequency of BRCA1 5382insC mutation in Russian breast cancer patients

BRCA1 5382insC variant was repeatedly detected in Jewish breast cancer (BC) families residing in USA and Israel as well as in non-Jewish familial BC patients from Poland, Latvia, Hungary, Russia and some other European countries. However, the distribution of BRCA1 5382insC mutation in unselected BC cases vs. controls has been systematically investigated mainly in Ashkenazi Jews. Here we applied a case-control study design in order to evaluate the impact of BRCA1 5382insC allele on BC incidence in St Petersburg, Russia. High frequency of the BRCA1 5382insC allele was detected in a group of bilateral breast cancer patients (10.4%; 15/144). Randomly selected unilateral BC cases demonstrated noticeable occurrence of BRCA1 5382insC mutation as well (3.7%; 32/857), with evident excess of the carriers in the early-onset (40 years) category (6.1%; 6/99) and in patients reporting breast and/or ovarian tumours in first-degree relatives (11.3%; 11/97). Strikingly, none of 478 middle-aged controls and 344 elderly tumour-free women carried the 5382insC variant. The presented data confirm a noticeable contribution of BRCA1 5382insC mutation in BC development in Russia, that may justify an extended BRCA1 5382insC testing within this population.     

Germ line BRCA1 & BRCA2 mutations in Greek breast/ovarian cancer families: 5382insC is the most frequent mutation observed

BRCA1 and BRCA2 genes were screened for loss-of-function mutations in a series of 85 patients having at least one first- or second-degree relative affected by breast and/or ovarian cancer. All BRCA1 exons and BRCA2 exons 10 and 11 were screened with a combination of methods including SSCP, PTT and direct sequencing. We have found disease-associated mutations in 14 families (16.5%), eleven in BRCA1 and three in BRCA2. The known founder mutation 5382insC of BRCA1 was identified in seven unrelated families. The other mutations identified include the non-sense R1751X, the splice junction variant 5586G>A of BRCA1 and three frameshifts, 2024del5, 3034del4, and 6631del5, of BRCA2. Nine out of these 14 families had a family history of three or more breast/ovarian cancer cases. A large number of polymorphic or unclassified variants is also reported. Combined with our previously published data 5382insC was found in nine out of 20 families (45%), suggesting that this mutation may represent a common founder mutation in the Greek population.     

High Incidence of 4153delA <Emphasis Type="Italic">BRCA1</Emphasis> Gene Mutations in Lithuanian Breast- and Breast-ovarian Cancer Families

Summary BRCA1 and BRCA2 gene mutations confer a high lifetime risk to breast and ovarian cancers. We have screened cancer patients from 13 families with at least three breast and/or ovarian cancers from Lithuania for 5382insC, C61G and 4153delA BRCA1 gene mutations. One of three mutations was found in 9 of the 13 studied families (69%). 4153delA was the most frequently detected and accounted for 56% of all identified mutation. 5382insC and C61G accounted for 33% and 11% of found mutations, respectively. Significantly higher, than in other populations, incidence of 4153delA indicates that this may be founder BRCA1 mutation characteristic for Lithuanians. Our analysis shows that testing of 4153delA, 5382insC, C61G BRCA1 mutations should be extremely effective and inexpensive tool in testing Lithuanian population aimed to identify individuals with high risk of breast and ovarian cancers.     

Double heterozygosity in the BRCA1 and BRCA2 genes in the Jewish population

BackgroundThe frequency and characteristics of disease in individuals who concomitantly harbor pathogenic mutations in both BRCA1 and BRCA2 genes are not established.Materials and methodsData were collected from the database of Clalit Health Services National Familial Cancer Consultation Service. Probands referred to this clinical service and their family members are routinely tested for the three Jewish founder mutations (BRCA1:185delAG, 5382insC, BRCA2:6174delT). In addition, carriers identified in a population-based cohort of all cases diagnosed with breast cancer in Israel in 1987–1988 allowed the estimation of the population frequency of this phenomenon.ResultsIn the clinic-based series of 1191 carriers of mutations in BRCA1 or BRCA2 belonging to 567 families, 22 males and females (1.85%) from 17 different families (3.0%) were found to harbor two different mutations. These included 18 individuals (1.51%) who concomitantly carried the 185delAG BRCA1 and the 6174delT BRCA2 mutations and four individuals (0.34%) who carried the 5382insC BRCA1 and the 6174delT mutations. All individuals were heterozygote carriers and none had a double mutation of both founder mutations in the BRCA1 gene itself. Seven of the 16 double carrier women (46.7%) had a personal history of breast carcinoma, diagnosed at a mean age of 44.6, compared with 372/926 (40.2%) carriers of a single mutation diagnosed with a mean age at diagnosis of 48.1 [odds ratio (OR) = 1.3, 95% confidence interval (CI) 0.4–4.0]. One case (6.7%) had a personal history of ovarian carcinoma diagnosed at the age of 53 compared with 55/926 (5.9%) of the women with single mutation (OR = 1.1, CI = 0.2–7.6). The frequency of double mutations in the population-based national breast cancer cohort was 2.2% of all carriers, and 0.3% of all breast cancer cases in the Ashkenazi population in the cohort. The mean age at diagnosis of breast cancer was younger in the carriers of two mutations.ConclusionDouble carriers of mutations in the BRCA genes are rare and seem to be carrying a similar probability of developing breast and ovarian cancers as carriers of single mutations.     

Prevalence of two <Emphasis Type="Italic">BRCA1</Emphasis> mutations, 5382insC and 300T &gt; G,in ovarian cancer patients from Ukraine

Ovarian cancer is the seventh most common cancer in women worldwide and the leading cause of gynecological malignant diseases-related deaths in women. The most significant risk factor for ovarian cancer is an inherited genetic mutation in one of two genes: breast cancer gene 1 (BRCA1) or breast cancer gene 2 (BRCA2). The germline mutation c.5266dupC (also known as 5382insC or 5385insC) is the most common mutation among Slavic patients with breast and/or ovarian cancer. Missense mutation c.181T?>?G (also known as 300T?>?G or p.C61G) is regarded as the founder change in many Central European countries. We screened 306 ovarian cancer patients diagnosed at different ages by mutagenically separated polymerase chain reaction (PCR) and real-time PCR. A total of 25 BRCA1 mutations were detected (18 cases of 5382insC and 7 cases of 300 T?>?G). The frequency of the BRCA1 5382insC mutation is similar in breast and ovarian cancer patients from Ukraine, but the frequency of 300T?>?G was estimated in Ukraine at first time.     

High prevalence of two BRCA1 mutations, 4154delA and 5382insC,in Latvia

Our aim was to characterise the germline BRCA1 mutation profile in Latvian breast cancer and ovarian cancer patients, to develop an effective BRCA1 gene mutation detection strategy, and to document genotype–phenotype correlations in mutation carriers. The entire BRCA1 gene was analysed in 75 breast cancer and 30 ovarian cancer patients. Screening for three mutations (5382insC, 4154delA and 300T>G) was carried out in 55 breast cancer and 66 ovarian cancer patients, and for two mutations, 5382insC and 4154delA, in 376 unselected patients with any cancer (including 51 breast cancer and 29 ovarian cancers) and 215 women with any gynaecological tumour. Mutation detection techniques used were SSCP/HD analysis or F-SSCP (ABI PRISM 310). Five different deleterious mutations were detected by analysis of the entire BRCA1 gene. The proportion of cases with mutations amongst 50 breast cancer patients diagnosed before 48 years was 26.0% (95% CI: 14.6–40.3%). Two mutations (5382insC and 4154delA) made up more than 80% of all mutations identified by the analysis of the entire BRCA1 gene in Latvia, at present. Further screening for only the prevalent mutations in different cancer patient groups resulted in the identification of 53 more mutation carriers. We conclude that breast cancer diagnosed before the age of 48 years and ovarian cancer before 65 years are criteria for DNA testing to be offered to women in Latvia, regardless of cancer history in the family. The observed associations of specific prevalent mutations with cancer site and age at onset of disease are discussed.     

Ovarian cancer risk in Ashkenazi Jewish carriers of BRCA1 and BRCA2 mutations.

PURPOSE: Several studies to date have reported ovarian cancer risk due to inherited BRCA1 and BRCA2 mutations using familial data or population-based series of probands. Familial aggregation associated with both of these methods may result in a substantial ascertainment bias. To address this, we have used a case-control design that does not involve familial aggregation to estimate the lifetime penetrance of ovarian cancer due to BRCA1 and BRCA2 mutations. EXPERIMENTAL DESIGN: A total of 382 ovarian cancer cases self-identified as being Jewish with no prior diagnosis of breast cancer were derived from two hospital-based series. In the first series, all 197 invasive epithelial ovarian cancer cases self-identified as Jewish and without a prior history of breast cancer, diagnosed and treated at Memorial Sloan-Kettering Cancer Center between 1986 and 2000, were identified. In the second series, 185 Jewish invasive epithelial ovarian cancer patients without prior breast cancer were identified in a study conducted at 11 centers in North America and Israel from 1995 to 1996. Controls were 3434 Jewish women without any prior history of breast or ovarian cancer from a large study of genotyped volunteers of Jewish origin in the Washington, D. C. area recruited by investigators at the National Cancer Institute. The cases and controls were genotyped for three Ashkenazi Jewish founder mutations, namely 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2. The lifetime penetrances were estimated using the odds ratios, mutation prevalence in the controls, and ovarian cancer incidence rates in the general American population obtained from the Surveillance, Epidemiology and End Results database adjusted for the incidence of ovarian cancer following breast cancer. RESULTS: Mutations were identified in 147 cases and 62 controls. The estimated penetrances at age 70 years were 37% (95% confidence interval, 25-71%) for a BRCA1 mutation and 21% (95% CI, 13-41%) for a BRCA2 mutation. CONCLUSIONS: The lifetime penetrances of BRCA1 mutations are lower than estimates obtained using familial data with multiple affected members but larger than estimates from some population-based proband series. The lifetime penetrance estimate of a BRCA2 mutation is in the range reported by some of the studies based on familial data. These results could have implications for clinical counseling, surgical interventions, and screening recommendations in women carrying these founder mutations.     

BRCA1 mutations and prostate cancer in Poland.

Evidence to date that BRCA1 mutation carriers are at an increased risk of prostate cancer is mixed - both positive and negative studies have been published. To establish whether or not inherited variation in BRCA1 influences prostate cancer risk we genotyped 1793 men with prostate cancer in Poland and 4570 controls for three founder mutations (C61G, 4153delA and 5382insC). A BRCA1 mutation was present in 0.45% of the cases and 0.48% of the controls (odds ratio=0.9; P=1.0). The odds ratios varied substantially by mutation. The 5382insC mutation is the most common of the three founder mutations. It was detected only in one case (0.06%), whereas it was seen in 0.37% of controls (P=0.06). In contrast, the 4153delA was more common in prostate cancer cases (0.22%) than in controls (0.04%) (odds ratio=5.1; 95% confidence interval: 0.9-27.9; P=0.1). The C61G mutation was also found in excess in cases (0.17%) compared with controls (0.07%) (odds ratio=2.6; 95% confidence interval: 0.5-12.7; P=0.5). Eight men with prostate cancer carried a mutation. Only one of these carried the 5382insC mutation, compared with 17 of 22 individuals with mutations in the control population (P=0.003). These data suggest that the 5382insC mutation is unlikely to be pathogenic for prostate cancer in the Polish population. The presence of one of the other alleles was associated with an increased risk for prostate cancer (odds ratio=3.6; 95% confidence interval: 1.1-11.3; P=0.045); in particular for familial prostate cancer (odds ratio=12; 95% confidence interval: 2.9-51; P=0.0004). We consider that the risk of prostate cancer in BRCA1 carriers varies with the position of the mutation.     

Differences in the characteristics of families with BRCA1 and BRCA2 mutations in Israel.

Three specific mutations in the BRCA1 (185delAG, 5382insC) and BRCA2 (6174delT) genes have been reported to be of high prevalence in the Jewish Ashkenazi population. We studied the differences in phenotype of families carrying these mutations. All consecutive families found by the CHS Familial Cancer Service to carry one of the three 'Jewish' mutations of the BRCA1/BRCA2 genes were evaluated for phenotypic characteristics. Chi-squared and Student's t-test statistics were employed to study differences in a variety of clinical and demographic parameters. A total of 111 families with 1499 family members were included. Among them 454 cases of cancer (297 in breast/ovary) were reported. Ovarian cancer, but not breast cancer, was detected at a significantly younger age among carriers of 185delT compared with other mutation carriers. In families with 185delAG, 5382insC and 6174delT mutations, breast cancer was found in 20.2, 39.4 and 24.1% of all identified women (born between 1900 and 1975), correspondingly. The corresponding figures for ovarian cancer were 13.9, 6.8 and 4.9%. Families carrying the 5382insC mutation had the highest probability of expressing bilateral breast cancer (38.9% of families, 15.4% of women with cancer, 6.1% of all women in family) and metachronous breast and ovary tumours (22.2, 9.8 and 4.5% correspondingly). Other tumours were reported in 7.9, 9.1 and 12.0% of women and 9.5, 12.9 and 15.8% of men in families with 185delAG, 5382insC, 6174delT, correspondingly. Marked phenotypic differences were found between families carrying different BRCA mutations warranting mutation-specific counselling to families seeking risk-reduction advice. 5382insC emerged as a most aggressive mutation.     

Hereditary ovarian cancer in Poland

There is increasing evidence that hereditary factors play a greater role in ovarian cancer than in any of the other common cancers of adulthood. This is attributable, to a large extent, to a high frequency of mutations in the BRCA1 or BRCA2 genes. In Poland, 3 common founder mutations in BRCA1 account for the majority of families with identified BRCA mutations. Our study was conducted in order to estimate the prevalence of any of 3 founder BRCA1 mutations (5382insC, C61G and 4153delA) in 364 unselected women with ovarian cancer, and among 177 women with ovarian cancer and a family history of breast or ovarian cancer. A mutation was identified in 49 out of 364 unselected women with ovarian cancer (13.5%) and in 58 of 177 women with familial ovarian cancer (32.8%). The majority of women with ovarian cancer and a BRCA1 mutation have no family history of breast or ovarian cancer. The high frequency of BRCA1 mutations in Polish women with ovarian cancer supports the recommendation that all Polish women with ovarian cancer should be offered testing for genetic susceptibility, and that counseling services be made available to them and to their relatives. It is important that mutation surveys be conducted in other countries prior to the introduction of national genetic screening programs.     

Founder mutations in early-onset, familial and bilateral breast cancer patients from Russia

Previous studies indicate that founder mutations may play a noticeable role in breast cancer (BC) predisposition in Russia. Here we performed a systematic analysis of eight recurrent mutations in 302 BC cases (St.-Petersburg, Russia), which were selected due to the presence of clinical indicators of hereditary disease (bilaterality and/or early onset (≤40 years) and/or family history). BC-associated alleles were revealed in 46 (15.2%) women. BRCA1 5382insC mutation was detected in 29 (9.6%) patients, CHEK2 1100delC in 9 (3.0%), BRCA1 4153delA in 3 (1.0%), CHEK2 IVS2+1G>A in 2 (0.7%), and BRCA1 185delAG, BRCA2 6174delT and NBS1 657del5 in 1 (0.3%) patient each. No cases with BRCA1 300T>G (C61G) mutation was identified. The obtained data suggest that a significant fraction of hereditary BC cases in Russia can be diagnosed using only a limited number of simple PCR tests.     

Survival after breast cancer in Ashkenazi Jewish BRCA1 and BRCA2 mutation carriers

BACKGROUND: Studies of survival following breast and ovarian cancers in BRCA1 and/or BRCA2 mutation carriers have yielded conflicting results. We undertook an analysis of a community-based study of Ashkenazi Jews to investigate the effect of three founder mutations in BRCA1 and BRCA2 on survival among patients with breast or ovarian cancer. METHODS: We collected blood samples and questionnaire data from 5318 Ashkenazi Jewish volunteers. The blood samples were tested for 185delAG (two nucleotide deletion) and 5382insC (single nucleotide insertion) mutations in BRCA1 and the 6174delT (single nucleotide deletion) mutation in BRCA2. To estimate survival differences in the affected relatives according to their BRCA1 and/or BRCA2 mutation carrier status, we devised and applied a novel extension of the kin-cohort method. RESULTS: Fifty mutation carriers reported that 58 of their first-degree relatives had been diagnosed with breast cancer and 10 with ovarian cancer; 907 noncarriers reported 979 first-degree relatives with breast cancer and 116 with ovarian cancer. Kaplan-Meier estimates of median survival after breast cancer were 16 years (95% confidence interval [CI] = 11-40) in the relatives of carriers and 18 years (95% CI = 15-22) in the relatives of noncarriers, a difference that was not statistically significant (two-sided P = .87). There was also no difference in survival times among the 126 first-degree relatives with ovarian cancer. We found no survival difference between patients with breast or ovarian cancer who were inferred carriers of BRCA1 and/or BRCA2 mutations and noncarriers. CONCLUSIONS: Carriers of BRCA1 and BRCA2 mutations appeared to have neither better nor worse survival prognosis.     

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.     

Germline mutation analysis of BRCA1 and BRCA2 genes in Yugoslav breast/ovarian cancer families.

The frequency of germline BRCA1 and BRCA2 mutations was tested in Yugoslav breast and breast/ovarian cancer families using combined heteroduplex/single-strand conformation polymorphism analysis for the entire coding region of both genes. Three different recurrent BRCA1 mutations (one 185delAG, one 3447del4 and two 5382insC) were identified in 4 of 12 families (33%), whereas no definite disease-causing alterations of BRCA2 was detected. Genotype analysis revealed a possible common founder effect for each 185delAG and 5382insC. The relatively high frequency of germline BRCA1 mutations determined in this panel of families confirms the important role of BRCA1 in disease predisposition in the Yugoslav population, while the lack of population specific founder and/or unique mutations show the need of further analysis of samples from this yet unexamined region of Europe.     

A high proportion of founder BRCA1 mutations in Polish breast cancer families

Three mutations in BRCA1 (5382insC, C61G and 4153delA) are common in Poland and account for the majority of mutations identified to date in Polish breast and breast-ovarian cancer families. It is not known, however, to what extent these 3 founder mutations account for all of the BRCA mutations distributed throughout the country. This question has important implications for health policy and the design of epidemiologic studies. To establish the relative contributions of founder and nonfounder BRCA mutations, we established the entire spectrum of BRCA1 and BRCA2 mutations in a large set of breast-ovarian cancer families with origins in all regions of Poland. We sequenced the entire coding regions of the BRCA1 and BRCA2 genes in 100 Polish families with 3 or more cases of breast cancer and in 100 families with cases of both breast and ovarian cancer. A mutation in BRCA1 or BRCA2 was detected in 66% of breast cancer families and in 63% of breast-ovarian cancer families. Of 129 mutations, 122 (94.6%) were in BRCA1 and 7 (5.4%) were in BRCA2. Of the 122 families with BRCA1 mutations, 119 (97.5%) had a recurrent mutation (i.e., one that was seen in at least 2 families). In particular, 111 families (91.0%) carried one of the 3 common founder mutations. The mutation spectrum was not different between families with and without ovarian cancer. These findings suggest that a rapid and inexpensive assay directed at identifying the 3 common founder mutations will have a sensitivity of 86% compared to a much more costly and labor-intensive full-sequence analysis of both genes. This rapid test will facilitate large-scale national epidemiologic and clinical studies of hereditary breast cancer, potentially including studies of chemoprevention.