The 8765delAG mutation in BRCA2 is common among Jews of Yemenite extraction

Vascular endothelium function among male carriers of BRCA 1&2 germline mutation

Background: Breast cancer susceptibility genes 1&2 (BRCA1&2) mutations hinder DNA-repair. Germline mutations in these genes are known to cause cancer; however, they may have other consequences. In this study we evaluated for the first time, the effect of the BRCA mutations on the vascular endothelium of young healthy males. Results: The study included 82 participants (53 BRCA mutation positive-carriers and 29 negative-carriers). Subjects mean age was 40. There were no significant differences in the baseline characteristics of the two groups. BRCA-carriers had significantly higher levels of EPCs (fraction of CD34+/VEGF or CD133+/VEGF positive-cells) compared to non-carriers of the mutation (median 6.78[1.96,14.48]% vs. 1.46[0.65,6.18]%, p < 0.001, and median 7.17[1.70,16.69]% vs. 1.54[0.85,5.10]%, p < 0.001, respectively). This difference remained consistent after multivariate adjustment. We did not identify differences in endothelial function, endothelial damage markers and EPCs activity between the two groups. Methods: This was a prospective cohort study to test the association between BRCA status and possible endothelial alterations. The Study population included males, 18-50 years, with no cardiovascular morbidity, who were referred for BRCA screening. We tested the endothelial system by: Endothelial progenitor cells (EPC) production, endothelial function (EndoPAT2000), endothelial damage and related hormonal levels. We stratified the cohort by germline BRCA status and compared measurements between BRCA mutation positive- and negative-carriers. Conclusions: Male BRCA1&2 mutation positive-carriers had increased level of EPCs which may reflect a subclinical accumulative endothelial damage. These novel findings suggest that the effect of mutations in BRCA is not limited to increased cancer risk, but may affect the cardiovascular system.

BART-Seq: cost-effective massively parallelized targeted sequencing for genomics, transcriptomics, and single-cell analysis

We describe a highly sensitive, quantitative, and inexpensive technique for targeted sequencing of transcript cohorts or genomic regions from thousands of bulk samples or single cells in parallel. Multiplexing is based on a simple method that produces extensive matrices of diverse DNA barcodes attached to invariant primer sets, which are all pre-selected and optimized in silico. By applying the matrices in a novel workflow named Barcode Assembly foR Targeted Sequencing (BART-Seq), we analyze developmental states of thousands of single human pluripotent stem cells, either in different maintenance media or upon Wnt/β-catenin pathway activation, which identifies the mechanisms of differentiation induction. Moreover, we apply BART-Seq to the genetic screening of breast cancer patients and identify BRCA mutations with very high precision. The processing of thousands of samples and dynamic range measurements that outperform global transcriptomics techniques makes BART-Seq first targeted sequencing technique suitable for numerous research applications.

Is there a difference in testosterone levels and its regulators in men carrying BRCA mutations?

Background

Male BRCA mutation carriers are at risk for an early onset aggressive prostate cancer. No data exist on the association of testosterone levels among these patients. We aimed to analyze testosterone and associated hormonal levels among male BRCA carriers and non-carriers.

Patients and methods

Overall 87 male carriers and 43 non-carriers aged 40-70 were prospectively enrolled. Clinical data were collected and all patients were tested for total testosterone (TT), prostate specific antigen (PSA), follicle stimulating hormone (FSH), luteinizing hormone (LH), free androgen index (FAI), sex hormone binding globulin (SHBG) and prolactin. Multivariate linear regression analysis was performed to predict TT levels.

Results

The median age, mean BMI, comorbidities, PSA, FSH, LH and SHBG levels in both groups were similar. However, mean TT and FAI were higher in the carriers (16.7 nmol/l vs 13.5 nmol/l, p=0.03 and 39.5 vs 34.8, p=0.05, respectively), while prolactin was significantly lower. Multivariate analysis demonstrated that while BMI was inversely correlated to TT levels in both groups, LH was a predictor only in non-carriers.

Conclusions

Carriers have higher TT and FAI levels and lower prolactin levels; but LH does not predict their TT levels. Further research in a larger cohort of BRCA carriers with and without prostate cancer should be performed.

The yield of targeted genotyping for the recurring mutations in BRCA1/2 in Israel

BACKGROUND

Hereditary breast cancer is predominantly associated with germline mutations in the BRCA1 or BRCA2 genes. A few recurring mutations in these genes were reported in ethnically diverse Jewish populations. Since 2013, most oncogenetic laboratories in Israel adopted a two-step approach for BRCA1/2 genotyping, where the first step is genotyping for 14 seemingly recurring mutations-first-pass genotyping. The aim of this study was to assess the yield of this targeted BRCA sequencing.

METHODS

Clinical and genotyping data of all individuals who underwent oncogenetic counseling and first-pass BRCA genotyping at the Oncogenetic Service Sheba and Assaf Harofeh Medical Centers from 1 February 2013 to 30 June 2017 were reviewed. All study participants were unrelated to each other.

RESULTS

Overall, 5152 oncogenetic tests were reviewed in the present study, of which 4452 had no a priori known familial mutation. The majority of participants (68.6%) were genotyped because of personal history of cancer; 20.6% were tested because of family history of cancer, and details for the remaining 10.7% were missing. Overall, 256/4452 (5.8%) carriers were detected, 141 BRCA1 and 115 BRCA2 mutation carriers. In 54% of cancer-free carriers, no clinically suspicious family history of cancer was ascertained.

CONCLUSIONS

The currently used scheme of first-pass genotyping in Israel seems to have a high yield of mutation detection even in the absence of a significant family history of cancer. The challenge is to optimize the currently used targeted panel of common mutations and adjust it to the accumulating new data in the Israeli population.

Lower Urinary Tract Symptoms and Benign Prostate Hyperplasia Features Among Male BRCA Mutation Carriers

OBJECTIVE

To analyze lower urinary tract symptoms and benign prostate hyperplasia features among male BRCA1 and 2 carriers and an age-matched control group.

METHODS

Male BRCA carriers and noncarriers aged 40-70 years were enrolled in our cross-sectional study. Relevant clinical data were collected, and patients filled the International Prostate Symptom Score. Patients also underwent prostate-specific antigen (PSA) blood testing, digital rectal examination, uroflowmetry, and post-void residual ultrasound examination. As part of their routine follow-up, BRCA carriers underwent prostate magnetic resonance imaging.

RESULTS

Overall, 87 carriers and 30 noncarriers were enrolled. The median age, mean body mass index, and comorbidities in both groups were similar. Maximal flow (QMAX) was higher in the noncarrier group (16.9 mL/s vs 12 mL/s, P = .01). Mean prostate volume among all BRCA carriers was 38.8 cc (19.7), but BRCA1 patients had larger glands with higher mean PSA and PSA density than BRCA2 patients (41.8 cc vs 33.1 cc, P = .047, 1.84 ng/mL vs 1.07 ng/mL, P = .006, and .044 vs .032, P = .042, respectively). Multivariate analysis demonstrated age being the sole significant predictor of PSA density in BRCA2 patients.

CONCLUSION

Male carrying BRCA mutations have significantly lower QMAX than healthy men. BRCA1 patients have on average larger prostate glands and higher PSA than BRCA2 patients. Further research is required to decipher the association of lower urinary tract symptoms or benign prostate hyperplasia with BRCA carriers.

First case report of an adrenocortical carcinoma caused by a BRCA2 mutation

BACKGROUND

Adrenocortical carcinoma (ACC) may rarely be a component of inherited cancer syndromes such as Li-Fraumeni syndrome and Beckwith-Wiedemann syndrome. ACC caused by a BRCA2 mutation has never been reported.

METHODS

Nucleotide sequencing of BRCA2 in lymphocyte and tumoral DNA of a 50-year-old male who presented with an androgen-secreting ACC and a strong family history of breast, ovarian, and pancreatic cancers.

RESULTS

A germline BRCA2 2 bp heterozygous deletion at nucleotide 8765 (8765delAG) leading to a frameshift mutation (p.Glu2846GlyfsX23) was detected. Only the BRCA2 deleted allele was retained in the ACC tumoral DNA compared with the control DNA supporting a loss of heterozygosity in the tumor.

CONCLUSION

This is the first reported case of a patient with ACC associated with a BRCA2 germline mutation. Loss of heterozygosity in ACC DNA suggests a causal link with the BRCA2 8765delAG mutation.

A BRCA1 Frame Shift Mutation in Women of Kurdish Jewish Descent

Hereditary cancer comprises more than 10% of all breast cancer cases. In patients with a family history suggestive of a hereditary component, a mutation is often identified in the high penetrant genes BRCA1 and BRCA2. Several founder mutations have been detected in some Jewish communities, yet no BRCA1/2 founder mutation had been known in Kurdish Jews. Here, we describe the validation of a 22 hereditary cancer gene panel and a BRCA1 mutation found in 4 women from 2 unrelated Kurdish Jewish families utilizing this gene panel.

A panel spanning the coding sequences of 22 familial cancer-related genes was planned. Genomic DNA was taken to create libraries using this panel, which were then sequenced using the Ion Torrent PGM. The panel's validity in detecting mutations was tested on 25 samples with previously identified point mutations in the BRCA1, BRCA2, MLH1 and PMS2 genes; the panel did not test for large deletions or insertions. All previously identified mutations were detected. Next, a different set of 40 cancer patients of Kurdish Jewish descent diagnosed with cancer before the age of 50 years was tested. We identified the BRCA1 mutation, c.224_227delAAAG (dbSNP ID rs80357697), in 4 women from 2 unrelated Jewish Kurdish families. The probands were diagnosed with cancer at a young age and had significant family history, suggesting a founder mutation in this population. We suggest testing Kurdish Jewish women with a personal or family history of breast and/ or ovarian cancer for this mutation.

Breast and ovarian cancer risk and risk reduction in Jewish BRCA1/2 mutation carriers

PURPOSE

Mutations in BRCA1/2 dramatically increase the risk of both breast and ovarian cancers. Three mutations in these genes (185delAG, 5382insC, and 6174delT) occur at high frequency in Ashkenazi Jews. We evaluated how these common Jewish mutations (CJMs) affect cancer risks and risk reduction.

METHODS

Our cohort comprised 4,649 women with disease-associated BRCA1/2 mutations from 22 centers in the Prevention and Observation of Surgical End Points Consortium. Of these women, 969 were self-identified Jewish women. Cox proportional hazards models were used to estimate breast and ovarian cancer risks, as well as risk reduction from risk-reducing salpingo-oophorectomy (RRSO), by CJM and self-identified Jewish status.

RESULTS

Ninety-one percent of Jewish BRCA1/2-positive women carried a CJM. Jewish women were significantly more likely to undergo RRSO than non-Jewish women (54% v 41%, respectively; odds ratio, 1.87; 95% CI, 1.44 to 2.42). Relative risks of cancer varied by CJM, with the relative risk of breast cancer being significantly lower in 6174delT mutation carriers than in non-CJM BRCA2 carriers (hazard ratio, 0.35; 95% CI, 0.18 to 0.69). No significant difference was seen in cancer risk reduction after RRSO among subgroups.

CONCLUSION

Consistent with previous results, risks for breast and ovarian cancer varied by CJM in BRCA1/2 carriers. In particular, 6174delT carriers had a lower risk of breast cancer. This finding requires additional confirmation in larger prospective and population-based cohort studies before being integrated into clinical care.

Germline mutations in BRCA1 and BRCA2 genes in ethnically diverse high risk families in Israel

Three mutations in BRCA1 (185delAG, 5382InsC) and BRCA2 (6174delT) predominate among high risk breast ovarian cancer Ashkenazi Jewish families, with few "private" mutations described. Additionally, the spectrum of BRCA1 and BRCA2 germline mutations among high risk Jewish non Ashkenazi and non Jewish Israelis is undetermined. Genotyping by exon-specific sequencing or heteroduplex analysis using enhanced mismatch mutation analysis was applied to 250 high risk, predominantly cancer affected, unrelated Israeli women of Ashkenazi (n = 72), non Ashkenazi (n = 90), Moslem (n = 45), Christian Arabs (n = 21), Druze (n = 17), and non Jewish Caucasians (n = 5). All Jewish women were prescreened and did not harbor any of the predominant BRCA1 or BRCA2 Jewish mutations. Age at diagnosis of breast cancer (median ± SD) (n = 219) was 40.1 ± 11.7, 45.6 ± 10.7, 38.7 ± 9.2, 45.5 ± 11.4 ± and 40.7 ± 8.1 years for Ashkenazi, non Ashkenazi, Moslem, Christian, and Druze participants, respectively. For ovarian cancer (n = 19) the mean ages were 45.75 ± 8.2, 57.9 ± 10.1, 54 ± 8, 70 ± 0, and 72 ± 0 for these origins, respectively. Overall, 22 (8.8%) participants carried 19 clearly pathogenic mutations-10 BRCA1 and 9 BRCA2 (3 novel): 3 in Ashkenazim, 6 in 8 non-Ashkenazim, 6 in 7 Moslems, 2 in Druze, and 2 in non Jewish Caucasians. Only three mutations (c.1991del4, C61G, A1708E) were detected in 2 seemingly unrelated families of Moslem and non- Ashkenazi origins. There were no inactivating mutations among 55 Ashkenazi high risk breast cancer only families. In conclusion, there are no predominant recurring germline mutations in BRCA1 or BRCA2 genes among ethnically diverse Jewish and non Jewish high risk families in Israel.

Preimplantation genetic diagnosis for BRCA1/2--a novel clinical experience

OBJECTIVE

To describe our 2-year experience with preimplantation genetic diagnosis (PGD) for carriers of mutations in the genes BRCA1 and BRCA2, the dilemmas incurred and the lessons learned.

METHODS

We collected data on those carriers of BRCA1/2 mutations who applied for PGD counseling and who decided to proceed. We describe the PGD procedures that were conducted and their outcome.

RESULTS

Ten carriers of BRCA1/2 mutations applied for PGD counseling, seven were healthy, and three were BC survivors. Eight women needed in vitro fertilization (IVF) because of coexisting infertility. After counseling, six opted for the procedure and five of them underwent PGD for the BRCA mutation. In one of these PGD, fluorescence in situ hybridization (FISH) analysis for chromosomes 21, X and Y was also performed. Three women conceived, each in the first treatment attempt. One of them gave birth to twins, the second to a singleton and the third is currently pregnant. During the pregnancies, dilemmas concerning PGD confirmation were discussed.

CONCLUSIONS

PGD is an acceptable reproductive option for BRCA mutation carriers, especially for those who require IVF due to fertility problems. Discussion of this option should be carried out with sensitivity, taking into account the age of the woman, her health, fertility status and emotional state. Confirmatory prenatal diagnosis may not always be encouraged.

Origin and distribution of the BRCA2-8765delAG mutation in breast cancer

Background

The BRCA2-8765delAG mutation was firstly described in breast cancer families from French-Canadian and Jewish-Yemenite populations; it was then reported as a founder mutation in Sardinian families. We evaluated both the prevalence of the BRCA2-8765delAG variant in Sardinia and the putative existence of a common ancestral origin through a haplotype analysis of breast cancer family members carrying such a mutation.

Methods

Eight polymorphic microsatellite markers (D13S1250, centromeric, to D13S267, telomeric) spanning the BRCA2 gene locus were used for the haplotype analysis. Screening for the 8765delAG mutation was performed by PCR-based amplification of BRCA2-exon 20, followed by automated sequencing.

Results

Among families with high recurrence of breast cancer (≥ 3 cases in first-degree relatives), those from North Sardinia shared the same haplotype whereas the families from French Canadian and Jewish-Yemenite populations presented distinct genetic assets at the BRCA2 locus. Screening for the BRCA2-8765delAG variant among unselected and consecutively-collected breast cancer patients originating from the entire Sardinia revealed that such a mutation is present in the northern part of the island only [9/648 (1.4%) among cases from North Sardinia versus 0/493 among cases from South Sardinia].

Conclusion

The BRCA2-8765delAG has an independent origin in geographically and ethnically distinct populations, acting as a founder mutation in North but not in South Sardinia. Since BRCA2-8765delAG occurs within a triplet repeat sequence of AGAGAG, our study further confirmed the existence of a mutational hot-spot at this genomic position (additional genetic factors within each single population might be involved in generating such a mutation).

The P1812A and P25TBRCA1and the 5164del4BRCA2Mutations: Occurrence in High-Risk Non-Ashkenazi Jews

Founder mutations in the BRCA1 and BRCA2 genes have been discovered in the Ashkenazic Jewish population, but a founder mutation(s) has not been discovered among non-Ashkenazi Jews (NAJ). Two BRCA1 mutations (P1812A, P25T), and a BRCA2 mutation (5164del4) have been detected in NAJ high-risk families. We studied the prevalence of these three mutations in 270 high-risk NAJ families, including 85 from Iraq/Iran, 67 from North Africa, 27 from Yemen, 50 from the Balkan region, and 41 with mixed ancestry. The three mutations were detected only in individuals related to the original families. We conclude that the P1812A and P25T BRCA1 and 5164del4 BRCA2 mutations are not likely to be founder mutations in NAJ high-risk families. We also assessed the pathogenicity of the BRCA1 P1812A mutation in vitro using reporter gene assays in yeast and mammalian cells. We found that the BRCA1 P1812A variant activity assays yielded a slightly reduced reporter gene activity. Thus, there is some uncertainty as to the pathogenicity of BRCA1 P1812A.

Acceptance of preventive surgeries by Israeli women who had undergone BRCA testing

Using a specially constructed questionnaire, the effect of BRCA test results for the Jewish founder mutations and genetic counseling on women's attitudes towards and acceptance of preventive surgeries was evaluated. The subjects consisted of 99 women 43% of whom were found to be carriers as opposed to 57%--non-carriers. After learning of their genetic status, 94% of the carriers and 28% of the non-carriers declared having positively considered the option of preventive oophorectomy. However, only about 25% of the carriers and 4.5% of the non-carriers had positively considered the option of preventive mastectomy. In practice, 78% of the carriers and 18% of the non-carriers who proved to be eligible for these procedures underwent preventive oophorectomy compared with 19% of carriers and 1.8% of non-carriers who underwent preventive mastectomy. Almost all carriers, as well as a majority of the non-carriers, who finally opted for the preventive surgeries did so after learning the result of their genetic test. The different attitudes toward the two surgeries were found to be based on varied beliefs regarding the two procedures. Preventive oophorectomy was perceived as being more acceptable to women than preventive mastectomy both from an attitudinal as well as practical aspect. These differences may be the result of cultural factors, of women's trust in the ability of screening tests to prevent morbidity and/or mortality, of the effect of the surgeries on body image and of different counseling protocols.

The Jewish people: their ethnic history, genetic disorders and specific cancer susceptibility

The Jews are an ancient and unique group of people linked by language, religion and customs in spite of their major geographical shifts, expulsions, forced conversions and massacres throughout their entire history. As a result of these historical events that led to repeated migration, the Jewish people became dispersed into various ethnic sub-groups. Between these ethnic groups exists heterogeneity, as well as some similarities, to the populations amongst whom they lived. Rare genetic diseases have been reported to be prevalent among the different groups of Jews, which for the most part can be explained by random genetic drift together with intra-familial marriages. In this publication, we will briefly discuss the origin of the various ethnic groups and some of the genetic diseases commonly found in them, with emphasis on the Ashkenazim, their prevalent genetic diseases and cancer susceptibility.

Significant proportion of breast and/or ovarian cancer families of French Canadian descent harbor 1 of 5BRCA1 andBRCA2 mutations

In 1998, we reported that a significant proportion of breast and/or ovarian cancer families of French Canadian descent harbor specific germline mutations in BRCA1 or BRCA2 attributed to common founders. Here we report the frequency of previously described mutations (n = 7) and 13 mutations identified in French Canadian families since 1998, in a new group of families (n = 88). Four of the previously described mutations, 4446C>T, 2953delGTAinsC, 8765delAG and 6085C>T, account for 72% and 69% of mutation-positive families in previously (n = 81) and recently ascertained groups, respectively. Only 2 of 13 recently identified mutations were found in more than 1 family: 3875delGTCT (n = 2) and 3398delAAAAG (n = 4). The 2 groups (ascertained pre- and post-gene discovery) did not differ significantly when distribution of mutations based on cancer syndrome phenotype and age of diagnosis or number of breast cancer cases were compared. Five common mutations accounted for a significant proportion (84%) of all mutation-positive families. The age of diagnosis of female breast cancer in mutation-negative families was significantly higher than that of the mutation-positive families (p<0.0001). The total number of cases of cancer per family was significantly lower in mutation-negative than mutation-positive families (p<0.001). Our results define a new mutation panel for screening BRCA1/2 mutations and the phenotype of mutation-positive families harboring the common mutations in the French Canadian population.

A low frequency of non-founder BRCA1 mutations in Ashkenazi Jewish breast-ovarian cancer families

The 185delAG and 5382insC founder mutations account for the majority of mutations identified in BRCA1 in Ashkenazi Jewish breast and breast-ovarian cancer families. Few non-founder BRCA1 mutations have been identified to date in these families. We initially screened a panel of 245 Ashkenazi Jewish breast-ovarian cancer families with an affected proband and at least one other case of breast or ovarian cancer for founder mutations in BRCA1 and BRCA2. Founder mutations were identified in 85 families (185delAG in 44 families, 5382insC in 16 families, and the BRCA2 6174delT in 25 families). The 160 negative families were then screened for the entire BRCA1 gene by a combination of DGGE and PTT. We identified one novel frameshift mutation in BRCA1 in exon 14 (4572del22) that truncated the protein at codon 1485. The family contained three cases of early-onset ovarian cancer (41 years, 43 years, and 52 years) and one case of breast cancer (at age 54 years subsequent to an ovarian cancer). In addition, three missense variants of unknown significance (exon 11 C3832T (P1238L), exon 15 G4654T (S1512I), and exon 15 G4755A (D1546N)) were found in single families. These missense variants have been previously identified in other families [BIC Database] and are considered to be "unclassified variants, favoring polymorphism." Non-founder BRCA1 mutations are rare in Ashkenazi Jewish breast/ovarian cancer families.

Haplotype analysis of BRCA2 8765delAG mutation carriers in French Canadian and Yemenite Jewish hereditary breast cancer families

The BRCA2 8765delAG mutation was previously reported in hereditary breast cancer families of French Canadian and Yemenite Jewish descent. Haplotype analysis, using six microsatellite markers that span BRCA2 and two intragenic polymorphisms, was performed on 8765delAG mutation carriers to determine if there was evidence that the mutations were identical by descent. The alleles of the microsatellite markers most closely flanking BRCA2 (D13S1697 and D13S1701) were found to be identical in state in all the mutation carriers. However, the disease-associated allele of one of the intragenic markers differed between the Yemenite Jews and French Canadian families, indicating that the 8765delAG mutation has independent origins in these two geographically and ethnically distinct populations.

Mutational analyses of BRCA1 and BRCA2 in Ashkenazi and non-Ashkenazi Jewish women with familial breast and ovarian cancer

In Ashkenazi (East European) Jews, three predominant mutations in BRCA1 (185delAG and 5382insC) and BRCA2 (6174delT) account for the majority of germline mutations in high-risk breast and/or ovarian cancer families. Among non-Ashkenazi Jews, the 185delAG, Tyr978Ter, and a handful of "private" mutations have been reported anecdotally within both genes. In this study we attempted to determine the spectrum of BRCA1 and BRCA2 mutations in high-risk Jewish individuals, non-carriers of any of the predominant Jewish mutations. We employed multiplex PCR and denaturing gradient gel electrophoresis (DGGE) analysis for BRCA2, and combined denaturing high performance liquid chromatography (DHPLC) and protein truncation test (PTT) for BRCA1, complemented by DNA sequencing. We screened 47 high-risk Jewish individuals, 26 Ashkenazis, and 21 non-Ashkenazis. Overall, 13 sequence alterations in BRCA1 and eight in BRCA2 were detected: nine neutral polymorphisms and 12 missense mutations, including five novel ones. The novel missense mutations did not co-segregate with disease in BRCA1 and were detected at rates of 6.25% to 52.5% in the general population for BRCA2. Our findings suggest that except for the predominant mutations in BRCA1 and BRCA2 in Jewish individuals, there are only a handful of pathogenic mutations within these genes. It may imply novel genes may underlie inherited susceptibility to breast/ovarian cancer in Jewish individuals.

Identification of a founder BRCA2 mutation in Sardinia

Sardinian population can be instrumental in defining the molecular basis of cancer, using the identity-by-descent method. We selected seven Sardinian breast cancer families originating from the northern-central part of the island with multiple affected members in different generations. We genotyped 106 members of the seven families and 20 control nuclear families with markers flanking BRCA2 locus at 13q12-q13. The detection of a common haplotype shared by four out of seven families (60%) suggests the presence of a founder BRCA2 mutation. Direct sequencing of BRCA2 coding exons of patients carrying the shared haplotype, allowed the identification of a 'frame-shift' mutation at codon 2867 (8765delAG), causing a premature termination-codon. This mutation was found in breast cancer patients as well as one prostate and one bladder cancer patient with shared haplotype. We then investigated the frequency of 8765delAG in the Sardinian breast cancer population by analysing 270 paraffin-embedded normal tissue samples from breast cancer patients. Five patients (1.7%) were found to be positive for the 8765delAG mutation. Discovery of a founder mutation in Sardinia through the identity-by-descent method demonstrates that this approach can be applied successfully to find mutations either for breast cancer or for other types of tumours.