BRCA1 and BRCA2 mutation analysis in breast-ovarian cancer families from northeastern Poland

Sixty high-risk breast and/or ovarian cancer families from North-Eastern Poland were screened for germline mutations in BRCA1 (MIM# 113705) and BRCA2 (MIM# 600185), using a combination of protein truncation test, denaturing high-performance liquid chromatography and direct sequencing. Sixteen (27%) of the families were found to carry nine different BRCA mutations, including 14 families with BRCA1 mutation and two families with BRCA2 mutation. The results suggest the presence of two strong BRCA1 founder mutations in the Polish population - 5382insC (6 families) and 300T>G (Cys61Gly; 3 families). The remaining seven mutations were found in single families and included three previously reported BRCA1 mutations (185delAG, 2682C>T [Gln855Ter] and 3819del5), a novel BRCA1 mutation (IVS14+1G>A), as well as two BRCA2 mutations (4088delA and 7985G>A [Trp2586Ter]) not previously observed in Polish families. We confirm the strong influence of two Central-Eastern European BRCA1 founder mutations in familial breast and/or ovarian cancer in Poland. We also conclude that the Polish population has a more dispersed BRCA mutation spectrum than had been earlier thought. This warrants further careful BRCA mutation screening in order to optimise genetic counselling and disease prevention in affected families.     

Strong founder effects in BRCA1 mutation carrier breast cancer patients from Latvia

Germ‐line mutations of the BRCA1 gene account for approximately half of the cases of hereditary breast/ovarian cancers. We have screened index patients from 15 breast cancer families and 8 sporadic breast cancer patients from Latvia for mutations in all coding exons of the BRCA1 gene, using combined Heteroduplex Analysis/SSCP followed by direct sequencing of the variants. BRCA1 germ‐line mutations proved to be frequent in Latvian breast cancer patients, also in moderate‐risk families and sporadic patients. Out of 23 cases a total of 8 patients (35%) exhibited three different mutations (5382insC, C61G, 4153delA). Interestingly, these three recurrent mutations accounted for all mutations in our sample set and no unique mutation was found. The 5382insC and C61G mutations accounted for 63% (5/8) and 25% (2/8) of all mutations, respectively. Allelotyping suggested a common founder in each recurrent mutation. Additional one‐hundred hospital‐based incident breast cancer patients were screened for the three mutations and 4 other 5382insC mutation carriers were identified (4%). Patients with C61G and 4153delA mutations were all Latvians, whilst the majority of 5382insC carriers (7/9=78%) were of Russian ethnicity, which is intriguing for the supposed Baltic origin of this mutation. Hum Mutat 14:92, 1999. © 1999 Wiley‐Liss, Inc.     

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.     

Frequency of three BRCA1 gene founder mutations in breast/ovarian cancer families from the Pomerania-Kujawy region of Poland

A group of 63 families from the Pomerania-Kujawy region were analyzed for three BRCA1 gene Polish founder mutations, 5382insC, 300T>G, and 4153delA, because of breast (BrCa) and/or ovarian cancer (OvCa) history. The analysis was carried out by multiplex polymerase chain reaction method. BRCA1 mutation was revealed in nine (14%) families: in three (33%) of hereditary BrCa and OvCa families, in three (8%) of hereditary BrCa families, and in three (21%) of hereditary OvCa families. According to risk criteria, it was revealed in 45% of high-risk families with more than three cancers, 13% of moderate-risk families with two cancers, and 8% of families with sporadic OvCa. In six families, the mutation was found in a proband with BrCa or OvCa and in three families, the mutation was found in a healthy proband, first-degree relative of a patient deceased of BrCa or OvCa. 5382insC frameshift mutation accounted for 67% and 300T>G missense mutation for 33% of all identified familial mutations. 4153delA frameshift mutation was not found in analyzed sample of families. 5382insC mutation was found in 9% and 300T>G in 5% of all investigated families, and in 27 and 18%, respectively, of high-risk families. This underlines the importance of applying strict inclusion criteria to analyze mutation frequency in hereditary BrCa/OvCa families.     

The contribution of founder mutations in BRCA1 to breast cancer in Belarus

Uglanitsa N, Oszurek O, Uglanitsa K, Savonievich E, Lubiński J, Cybulski C, Debniak T, Narod SA, Gronwald J. The contribution of founder mutations in BRCA1 to breast cancer in Belarus. Mutations in the BRCA1 gene increase susceptibility to both breast and ovarian cancer. In some countries, including several in Eastern Europe, founder mutations in the BRCA1 gene are responsible for a significant proportion of breast cancer cases. To estimate the hereditary proportion of breast cancer in Belarus, we sought the presence of any of three founder mutations in BRCA1 (4153delA, 5382insC and C61G) in 500 unselected cases of breast cancer. These mutations have previously been identified in breast/ovarian cancer families from Belarus and from other Slavic countries, including Poland and Russia. One of the three founder mutations in BRCA1 was present in 38 of 500 unselected cases of breast cancer (7.6%). A mutation was found in 12.6% of women diagnosed before age 50 and 5.6% of women diagnosed after age 50. A mutation was identified in 2 of 251 newborn controls (0.8%). The hereditary proportion of breast cancers in Belarus is among the highest of any countries studied to date.     

Founder BRCA1 mutations and two novel germline BRCA2 mutations in breast and/or ovarian cancer families from North-Eastern Poland

Germline mutations in the BRCA1 and BRCA2 genes account for the majority of high-risk breast/ovarian cancer families, depending on the population studied. Previously, BRCA1 mutations were described in women from Western Poland. To further characterize the spectrum of BRCA1 mutations and the impact of BRCA2 mutations in Poland, we have analyzed 25 high-risk breast and/or ovarian cancer families from North-Eastern Poland for mutations in all coding exons of the BRCA1 and BRCA2 genes, using combined heteroduplex analysis/SSCP followed by direct DNA sequence analysis. Out of 25 probands a total of five (20%) carried three recurrent BRCA1 mutations (300T>G, 3819del5, 5382insC). The 300T>G mutation accounted for 60% (3/5) of BRCA1 mutations and allelotyping suggested a common founder of this mutation. No unique mutations were found. In addition, we identified three BRCA2 (12%) mutations, one recurrent 4075delGT, and two novel frameshift mutations, 7327ins/dupl19 and 9068delA. We conclude that 30% of high-risk families from North-Eastern Poland may be due to recurrent BRCA1 and unique BRCA2 mutations. Intriguingly, the BRCA1 mutation spectrum seems to be different within subregions of Poland.     

The contribution of founder mutations in BRCA1 to breast and ovarian cancer in Lithuania

Elsakov P, Kurtinaitis J, Petraitis S, Ostapenko V, Razumas M, Razumas T, Meskauskas R, Petrulis K, Luksite A, Lubiński J, Górski B, Narod SA, Gronwald J. The contribution of founder mutations in BRCA1 to breast and ovarian cancer in Lithuania. We evaluated the prevalence of BRCA1 founder mutations in unselected cases of breast, ovarian and colon cancer from Lithuania. We identified a founder mutation (4153delA, 5382insC or C61G) in 6% of 235 unselected cases of breast cancer and in 19% of 43 unselected cases of ovarian cancer. Only one patient with a mutation was identified among 178 cases of colon cancer. No mutation was identified among 422 newborn controls. This data indicates that the genetic burden of breast and ovarian cancer attributable to BRCA1 mutations in Lithuania is very high and supports the recommendation that all cases of breast and ovarian cancer in Lithuania be offered genetic testing.     

Prevalence of BRCA1 founder mutations in western Poland

The frequency of three BRCA1 founder mutations was examined in a group of Polish breast/ovarian cancer patients and women at increased risk of these cancers based on family history. Among the 15 mutations found (5385-5386insC, 187-188delAG, and 4154delA), eight were detected in women with a low or moderate family history. The frequency of the IVS20+48ins12 variant was also analyzed and its distribution within risk groups argues against its involvement in cancer predisposition.     

BRCA1 and BRCA2 mutations in Russian familial breast cancer

We have screened index cases from 25 Russian breast/ovarian cancer families for germ‐line mutations in all coding exons of the BRCA1 and BRCA2 genes, using multiplex heteroduplex analysis. In addition we tested 22 patients with breast cancer diagnosed before age 40 without family history and 6 patients with bilateral breast cancer. The frequency of families with germline mutations in BRCA was 16% (4/25). One BRCA1 mutation, 5382insC, was found in three families. The results of present study, and those of a separate study of 19 breast‐ovarian cancer families, suggest that BRCA1 5382insC is a founder mutation in the Russian population. Three BRCA2 mutations were found in patients with breast cancer without family history: two in young patients and one in patients with bilateral breast cancer. Four novel BRCA2 mutations were identified: three frameshift (695insT, 1528del4, 9318del4) and one nonsense (S1099X). © 2002 Wiley‐Liss, Inc.     

Prevalence of BRCA1 and BRCA2 mutations in unselected breast cancer patients from Peru

The prevalence of BRCA1 and BRCA2 mutations among breast cancer patients in Peru has not yet been explored. We enrolled 266 women with breast cancer from a National cancer hospital in Lima, Peru, unselected for age or family history. DNA was screened with a panel of 114 recurrent Hispanic BRCA mutations (HISPANEL). Among the 266 cases, 13 deleterious mutations were identified (11 in BRCA1 and 2 in BRCA2), representing 5% of the total. The average age of breast cancer in the mutation‐positive cases was 44 years. BRCA1 185delAG represented 7 of 11 mutations in BRCA1. Other mutations detected in BRCA1 included: two 2080delA, one 943ins10, and one 3878delTA. The BRCA2 3036del4 mutation was seen in two patients. Given the relatively low cost of the HISPANEL test, one should consider offering this test to all Peruvian women with breast or ovarian cancer.     

Risk factors for detecting germline BRCA1 and BRCA2 founder mutations in Ashkenazi Jewish women with breast or ovarian cancer

We ascertained 184 Ashkenazi Jewish women with breast/ovarian cancer (171 breast and 13 ovarian cancers, two of the former also had ovarian cancer) in a self-referral study. They were tested for germline founder mutations in BRCA1 (185delAG, 5382insC, 188del11) and BRCA2 (6174delT). Personal/family histories were correlated with mutation status. Logistic regression was used to develop a model to predict those breast cancer cases likely to be germline BRCA1/BRCA2 mutation carriers in this population. The most important factors were age at diagnosis, personal/family history of ovarian cancer, or breast cancer diagnosed before 60 years in a first degree relative. A total of 15.8% of breast cancer cases, one of 13 ovarian cancer cases (7.7%), and both cases with ovarian and breast cancer carried one of the founder mutations. Age at diagnosis in carriers (44.6 years) was significantly lower than in non-carriers (52.1 years) (p<0.001), and was slightly lower in BRCA1 than BRCA2 carriers. Thirty three percent of carriers had no family history of breast or ovarian cancer in first or second degree relatives. Conversely, 12% of non-mutation carriers had strong family histories, with both a first and a second degree relative diagnosed with breast or ovarian cancer. The predicted values from the logistic model can be used to define criteria for identifying Ashkenazi Jewish women with breast cancer who are at high risk of carrying BRCA1 and BRCA2 mutations. The following criteria would identify those at approximately 10% risk: (1) breast cancer <50 years, (2) breast cancer <60 years with a first degree relative with breast cancer <60 years, or (3) breast cancer <70 years and a first or second degree relative with ovarian cancer.     

Cancer risks in first degree relatives of BRCA1 mutation carriers: effects of mutation and proband disease status

Background

Mutations in the BRCA1 (MIM 113705) gene are found in many families with multiple cases of breast and ovarian cancer, and women with a BRCA1 mutation are at significantly higher risk of developing breast and ovarian cancer than are the general public.

Methods

We obtained blood samples and pedigree information from 3568 unselected cases of early‐onset breast cancer and 609 unselected patients with ovarian cancer from hospitals throughout Poland. Genetic testing was performed for three founder BRCA1 mutations. We also calculated the risk of breast and ovarian cancer to age 75 in the first degree relatives of carriers using Kaplan‐Meier methods.

Results

The three founder BRCA1 mutations were identified in 273 samples (187 with 5382insC, 22 with 4153delA, and 64 with C61G). A mutation was present in 4.3% of patients with breast cancer and 12.3% of patients with ovarian cancer. The overall risk of breast cancer to age 75 in relatives was 33% and the risk of ovarian cancer was 15%. The risk for breast cancer was 42% higher among first degree relatives of carriers of the C61G missense mutation compared to other mutations (HR = 1.42; p = 0.10) and the risk for ovarian cancer was lower than average (OR = 0.26; p = 0.03). Relatives of women diagnosed with breast cancer had a higher risk of breast cancer than relatives of women diagnosed with ovarian cancer (OR = 1.7; p = 0.03).

Conclusions

The risk of breast cancer in female relatives of women with a BRCA1 mutation depends on whether the proband was diagnosed with breast or ovarian cancer.     

High frequency and allele‐specific differences of BRCA1 founder mutations in breast cancer and ovarian cancer patients from Belarus

Bogdanova NV, Antonenkova NN, Rogov YI, Karstens JH, Hillemanns P, Dörk T. High frequency and allele‐specific differences of BRCA1 founder mutations in breast cancer and ovarian cancer patients from Belarus. Breast cancer and ovarian cancer are common malignancies in Belarus accounting for about 3500 and 800 new cases per year, respectively. For breast cancer, the rates and age of onset appear to vary significantly in regions differentially affected by the Chernobyl accident. We assessed the frequency and distribution of three BRCA1 founder mutations 5382insC, 4153delA and Cys61Gly in two hospital‐based series of 1945 unselected breast cancer patients and of 201 unselected ovarian cancer patients from Belarus as well as in 1019 healthy control females from the same population. Any of these mutations were identified in 4.4% of the breast cancer patients, 26.4% of the ovarian cancer patients and 0.5% of the controls. In the breast cancer patients, BRCA1 mutations were strongly associated with earlier age at diagnosis, with oestrogen receptor (ER) negative tumours and with a first‐degree family history of breast cancer, although only 35% of the identified BRCA1 mutation carriers had such a family history. There were no marked differences in the regional distribution of BRCA1 mutations, so that the significant differences in age at diagnosis and family history of breast cancer patients from areas afflicted by the Chernobyl accident could not be explained by BRCA1. We next observed a higher impact and a shifted mutational spectrum of BRCA1 in the series of Byelorussian ovarian cancer patients where the three founder mutations accounted for 26.4% (53/201). While the Cys61Gly mutation appeared underrepresented in ovarian cancer as compared with breast cancer cases from the same population (p = 0.01), the 4153delA mutation made a higher contribution to ovarian cancer than to breast cancer (p < 0.01). BRCA1 mutations were significantly enriched among ovarian cancer cases with a first‐degree family history of breast or ovarian cancer, whereas the median age at ovarian cancer diagnosis was not different between mutation carriers and non‐carriers. Taken together, these results identify three BRCA1 founder mutations as key components of inherited breast and ovarian cancer susceptibility in Belarus and might have implications for cancer prevention, treatment and genetic counselling in this population.     

BRCA1 and BRCA2 founder mutations in patients with bilateral breast cancer

Bilateral breast cancer is traditionally considered an indirect indicator of inherited predisposition to cancer. To appreciate the contribution of genetic determinants to bilateral breast cancer in Jewish women we genotyped 55 such women for the three predominant mutations in BRCA1 (185delAG and 5382insC) and BRCA2 (6174delT) that account for the overwhelming majority of BRCA mutations in high-risk Jewish families. Among women with bilateral breast cancer, 17 mutation carriers (17/55; 29.6%) were identified. Individual mutation frequencies were 18.5% (10/55) for 185delAG, 3.7% (2/55) for 5382insC and 7.4% (5/55) for 6174delT. Carrier rate was significantly higher (P < 0.0016) in women with bilateral breast cancer whose first tumour was diagnosed at or before 42 years of age (82%; 14/17) than in women diagnosed after 42 years of age (7.9%; 3/38). Among patients with bilateral breast cancer and positive family history 45% (14/31) carried a BRCA mutation. Of these 86% (12/14) had one breast cancer diagnosed at or before 42 years of age. Our results suggest that bilateral breast cancer per se, in most cases, does not reflect genetic predisposition, unless associated with early age of onset (first tumour diagnosed at or before 42 years of age). Although the relationship between young age and carrier state in women with bilateral breast cancer is strong, no significant association between family history and carrier state was found. We can thus speculate that women with early onset breast cancer who carry a BRCA1 or BRCA2 mutation are prone to acquire a second breast tumour.     

High frequency of recurrent mutations in BRCA1 and BRCA2 genes in Polish families with breast and ovarian cancer

Germ-line mutations in BRCA1 and BRCA2 genes result in a significantly increased risk of breast and ovarian cancer. Other genes involved in an increased predisposition to breast cancer include the TP53 gene, mutated in Li-Fraumeni syndrome. To estimate the frequency of germ-line mutations in these three genes in Upper Silesia, we have analyzed 47 breast/ovarian cancer families from that region. We found five different disease predisposing mutations in 17 (36%) families. Twelve families (25.5%) carried known BRCA1 mutations (5382insC and C61G), four families (8.5%) carried novel BRCA2 mutations (9631delC and 6886delGAAAA), and one family (2%) harbored novel mutation 1095del8 in the TP53 gene, which is the largest germline deletion in coding sequence of this gene identified thus far. The 5382insC mutation in BRCA1 was found in 11 families and the 9631delC mutation in BRCA2 occurred in three families. These two mutations taken together contribute to 82% of all mutations found in this study, and 30% of the families investigated harbor one of these mutations. The very high frequency of common mutations observed in these families can only be compared to that reported for Ashkenazi Jewish, Icelandic, and Russian high-risk families. This frequency, however, may not be representative for the entire Polish population. The observed distribution of mutations will favor routine pre-screening of predisposed families using a simple and cost-effective test.     

An unaffected individual from a breast/ovarian cancer family with germline mutations in both BRCA1 and BRCA2

Currently many centers offer testing for three specific mutations, 185delAG, 5382insC, and 6174delT, in the BRCA1 and BRCA2 genes to Ashkenazi Jewish individuals at high risk for breast and ovarian cancer. We recently tested members of a family with multiple cases of breast and ovarian cancer (Family R014). The proband in this family tested positive for the 185delAG mutation. The unaffected sister of the proband tested positive for both the 185delAG and the 6174delT mutations. Further testing and review of the family history suggest that both mutations may have come from a maternal grandfather and passed down for two generations. Counseling of the unaffected double heterozygote individual in this family is complicated by lack of information on the risk of breast, ovarian, and other cancers in such individuals. A better understanding of these risks will depend on the identification and study of more individuals carrying mutations in both the BRCA1 and BRCA2 genes. Our study emphasizes the importance of testing Ashkenazi Jewish individuals from high-risk breast and ovarian cancer families for all three common BRCA1 and BRCA2 mutations identified in this ethnic group.     

Founder mutations in <Emphasis Type="Italic">BRCA1/2</Emphasis> are not frequent in Canadian Ashkenazi Jewish men with prostate cancer

Background  

Relatives of BRCA1 and BRCA2 mutation carriers have long been proposed by epidemiological studies to have an increased risk of developing prostate cancer. In the Ashkenazi Jewish (AJ) population, the existence of 3 frequent founder mutations, 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2 greatly facilitates screening for carriers.     

Screening for BRCA1 and BRCA2 mutations in Eastern Finnish breast/ovarian cancer families

Familial aggregation is thought to account for 5-10% of all breast cancer cases, and high penetrance breast and ovarian cancer susceptibility genes BRCA1 and BRCA2 explain < or =20% of these. Hundreds of mutations among breast/ovarian cancer families have been found in these two genes. The mutation spectrum and prevalence, however, varies widely among populations. Thirty-six breast/ovarian cancer families were identified from a population sample of breast and ovarian cancer cases among a relatively isolated population in Eastern Finland, and the frequency of BRCA1/BRCA2 germline mutations were screened using heteroduplex analysis, protein truncation test and sequencing. Five different mutations were detected in seven families (19.4%). Two mutations were found in BRCA1 and three in BRCA2. One of the mutations (BRCA2 4088insA) has not been detected elsewhere in Finland while the other four, 4216-2nt A-->G and 5370 C-->T in BRCA1 and 999del5 and 6503delTT in BRCA2, are recurrent Finnish founder mutations. These results add to the evidence of the geographical differences in distribution of Finnish BRCA1/BRCA2 mutations. This screen also provides further evidence for the presumption that the majority of Finnish BRCA1/BRCA2 founder mutations have been found and that the proportion of BRCA1/BRCA2 mutations in Finnish breast/ovarian cancer families is around 20%.     

Validation study of the LAMBDA model for predicting the BRCA1 or BRCA2 mutation carrier status of North American Ashkenazi Jewish women

LAMBDA is a model that estimates the probability an Ashkenazi Jewish (AJ) woman carries an ancestral BRCA1 or BRCA2 mutation from her personal and family cancer history. LAMBDA is relevant to clinical practice, and its implementation does not require a computer. It was developed principally from Australian and UK data. We conducted a validation study using 1286 North American AJ women tested for the mutations 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2. Most had a personal or family history of breast cancer. We observed 197 carriers. The area under the receiver operator characteristic (ROC) curve (a measure of ranking) was 0.79 [95% confidence interval (CI) = 0.77-0.81], similar to that for the model-generating data (0.78; 95% CI = 0.75-0.82). LAMBDA predicted 232 carriers (18% more than observed; p = 0.002) and was overdispersed (p = 0.009). The Bayesian computer program BRCAPRO gave a similar area under the ROC curve (0.78; 95% CI = 0.76-0.80), but predicted 367 carriers (86% more than observed; p < 0.0001), and was substantially overdispersed (p < 0.0001). Therefore, LAMBDA is comparable to BRCAPRO for ranking AJ women according to their probability of being a BRCA1 or BRCA2 mutation carrier and is more accurate than brcapro which substantially overpredicts carriers in this population.