Ashkenazi Jewish population frequencies for common mutations in BRCA1 and BRCA2

Clinical Considerations of BRCA1- and BRCA2-Mutation Carriers: A Review

Individuals who carry an inherited mutation in the breast cancer 1 (BRCA1) and BRCA2 genes have a significant risk of developing breast and ovarian cancer over the course of their lifetime. As a result, there are important considerations for the clinician in the counseling, followup and management of mutation carriers. This review outlines salient aspects in the approach to patients at high risk of developing breast and ovarian cancer, including criteria for genetic testing, screening guidelines, surgical prophylaxis, and chemoprevention.

RAD51C is a susceptibility gene for ovarian cancer

A homozygous mutation in the RAD51C gene was recently found to cause Fanconi anemia-like disorder. Furthermore, six heterozygous deleterious RAD51C mutations were detected in German breast and ovarian cancer families. We screened 277 Finnish familial breast or ovarian cancer patients for RAD51C and identified two recurrent deleterious mutations (c.93delG and c.837+1G>A). These mutations were further genotyped in 491 familial breast cancer patients, 409 unselected ovarian cancer patients and two series of unselected breast cancer cases (884 from Helsinki and 686 from Tampere) and population controls (1279 and 807, respectively). The mutation frequency among all breast cancer cases was not different from the controls (4 out of 2239, 0.2% versus population controls 2 out of 2086, 0.1%, P= 0.7). In the Helsinki series, each mutation was found in four cases with personal or family history of ovarian cancer. No mutations were found among cases with familial breast cancer only, four out of the eight carriers did not have family history of breast cancer. The mutations associated with an increased risk of familial breast and ovarian cancer (OR: 13.59, 95% CI 1.89-97.6, P= 0.026 compared with controls), but especially with familial ovarian cancer in the absence of breast cancer (OR: 213, 95% CI 25.6-1769, P= 0.0002) and also with unselected ovarian cancer (OR: 6.31, 95% CI 1.15-34.6, P= 0.033), with a significantly higher mutation rate among the familial cases (two out of eight, 25%) than the unselected ovarian cancer cases (4 out of 409, 1%) (OR: 33.8, 95% CI 5.15-221, P= 0.005). These results suggest RAD51C as the first moderate-to-high risk susceptibility gene for ovarian cancer.

Systematic review of breast cancer biology in developing countries (part 1): Africa, the middle East, eastern europe, Mexico, the Caribbean and South america

There has been no systematic appraisal of ethnicity-based variations in breast cancer (BC) biology amongst women from developing countries. A qualitative systematic review was conducted of breast cancer size, stage, grade, histological type, extra-mammary involvement, hormone receptor status as well as patient demographics. This review includes patients from Africa, the Middle East, Eastern Europe, Mexico, the Caribbean and South America. BC in these regions present at an earlier age with large aggressive tumours. Distant metastases are frequently present at the time of diagnosis. African women have a higher frequency of triple negative tumours. Over half of Middle Eastern women have lymph node involvement at the time of diagnosis. Despite experiencing a lower incidence compared to the Ashkenazi Jewish population, Palestinian women have poorer five-year survival outcomes. The majority of women from Mexico and South America have stage two or three disease whilst over sixty percent of women from Eastern Europe have either stage one or stage two disease. The biological characteristics of BC in the Caribbean cannot be fully assessed due to a paucity of data from the region. BC amongst the developing world is characterised by an early peak age of onset with aggressive biological characteristics. Strategies that improve breast cancer awareness, address amenable risk factors and improve early detection are essential.

Clinical management of hereditary breast cancer syndromes

Over the past 15 years there has been substantial improvement in the understanding of hereditary breast cancer. Germline genetic testing for mutations in BRCA1, BRCA2, PTEN and TP53 allows for the identification of individuals at increased risk for breast, ovarian and other cancers. Advances in screening, prevention and treatment have led to improved clinical management which is best defined for BRCA1 and BRCA2 mutation carriers. The addition of screening techniques such as breast magnetic resonance imaging has been shown to lead to earlier detection. Risk-reducing salpingo-oophorectomy leads to a reduction in the risk of both ovarian cancer and breast cancer and also is associated with an improvement in overall survival. BRCA1/2 mutation status may be applicable to systemic therapy decisions. Preclinical and early clinical research suggests that specific classes of chemotherapy may be more effective in mutation carriers. Finally, PARP inhibitors represent a novel therapeutic strategy that exploits the weaknesses of BRCA1/2-associated malignancies.

Jewish ethnicity and pancreatic cancer mortality in a large U.S. cohort

BACKGROUND

An association between Jewish ethnicity and pancreatic cancer risk was suggested by analyses comparing pancreatic cancer mortality rates between Jews and non-Jews in New York in the 1950s. These analyses lacked information on potential confounding factors and the association between Jewish ethnicity and pancreatic cancer has not been examined in any contemporary U.S. population or in any cohort study.

METHODS

We examined the association between Jewish ethnicity and pancreatic cancer mortality among approximately 1 million participants in the Cancer Prevention Study II cohort. Participants completed a questionnaire at enrollment in 1982 which included information on religion, smoking, obesity, and diabetes. During follow-up through 2006, there were 6,727 pancreatic cancer deaths, including 480 among Jewish participants. Proportional hazards modeling was used to calculate multivariable rate ratios (RR).

RESULTS

After adjusting for age, sex, smoking, body mass index, and diabetes, pancreatic cancer mortality was higher among Jewish participants than among non-Jewish whites (RR = 1.43; 95% CI, 1.30-1.57). In analyses by birthplace, RRs were 1.59 (95% CI, 1.31-1.93) for North American-born Jews with North American-born parents, 1.43 (95% CI, 1.27-1.61) for North American-born Jews with 1 or more parents born outside North America, and 1.03 (0.73, 1.44) for Jews born outside North America (P(heterogeneity) = 0.07).

CONCLUSIONS

These results support a higher risk of developing pancreatic cancer among U.S. Jews that is not explained by established risk factors.

IMPACT

Future studies may clarify the role of specific environmental or genetic factors responsible for higher risk among U.S. Jews.

Genetic testing and first presymptomatic diagnosis in Moroccan families at high risk for breast/ovarian cancer

Germline mutations in the BRCA1 and BRCA2 genes highly predispose to breast and ovarian cancers and are responsible for a substantial proportion of familial breast and ovarian cancers. No female individuals from families from Morocco affected by breast cancer with mutations of these genes have previously been reported, and clinicians in Morocco are unaccustomed to dealing with healthy female individuals carrying mutations in the BRCA genes. This study aimed to report the initial experience of a group of Moroccan investigators carrying out predictive genetic testing to detect a known familial mutation in healthy Moroccan females with a high risk of developing breast cancer and to introduce supervision of these asymptomatic female carriers as a new approach in the prevention and early diagnosis of breast and ovarian cancers in Morocco. Presymptomatic diagnosis was carried out using DNA genetic testing in 5 healthy Moroccan female individuals from three families with an elevated risk of developing breast cancer. These are the first Moroccan families reported to be affected by breast cancers associated with BRCA mutations. Presymptomatic diagnosis was carried out for breast cancer in 5 female individuals from three Moroccan families with BRCA mutations. Two of the families are the first reported incidence of the founder mutation Ashkenazi BRCA1-185_186delAG in Moroccan patients. The third family carried the known BRCA2 mutation c.5073dupA/p.trp1692metfsX3. We tested the presence of these mutations in 5 asymptomatic healthy females from the three families. Two sisters from family 1 carried the BRCA1-185_186delAG mutation, whereas the third female individual from family 2 carried the c.5073dupA/p.trp1692metfsX3 mutation. However, one healthy female individual and her mother from family 3 did not carry the familial mutation of the BRCA1 gene. This study found BRCA mutations in three asymptomatic subjects, suggesting that this is the first step towards the development of persistent medical monitoring of females from families with a history of breast and ovarian cancers. Consequently, it is crucial for oncologists in Morocco to initiate the supervision of healthy female individuals with genetic defects which may lead to hereditary cancers.

Breast cancer predisposition syndromes

A small, but important, percentage of breast cancer cases is caused by the inheritance of a single copy of a mutated gene. BRCA1 and BRCA2 are the genes most commonly associated with inherited breast cancer; however, mutations in TP53 and PTEN cause Li-Fraumeni syndrome and Cowden syndrome, respectively, both of which are associated with high lifetime risks of breast cancer. Advances in the field of breast cancer genetics have led to an improved understanding of detection and prevention strategies. More recently, strategies to target the underlying genetic defects in BRCA1- and BRCA2-associated breast and ovarian cancers are emerging and may have implications for certain types of sporadic breast cancer.

Characterization of two Ashkenazi Jewish founder mutations in MSH6 gene causing Lynch syndrome

Founder mutations are an important cause of Lynch syndrome and facilitate genetic testing in specific ethnic populations. Two putative founder mutations in MSH6 were analyzed in 2685 colorectal cancer (CRC) cases, 337 endometrial cancer (EnCa) cases and 3310 healthy controls of Ashkenazi Jewish (AJ) descent from population-based and hospital-based case–control studies in Israel, Canada and the United States. The carriers were haplotyped and the age of the mutations was estimated. MSH6*c.3984_3987dupGTCA was found in 8/2685 CRC cases, 2/337 EnCa cases, and 1/3310 controls, consistent with a high risk of CRC (odds ratio (OR) = 9.9, 95% confidence interval (CI) = 1.2–78.9, p = 0.0079) and a very high risk of EnCa (OR = 19.6, 95% CI = 1.8–217.2, p = 0.0006). MSH6*c.3959_3962delCAAG was identified in 3/2685 CRC cases, 2/337 EnCa cases and no controls. Each mutation was observed on separate conserved haplotypes. MSH6*c.3984_3987dupGTCA and MSH6*c.3959_3962delCAAG probably arose around 585 CE and 685 CE, respectively. No carriers were identified in Sephardi Jews (450 cases and 490 controls). Truncating mutations MSH6*c.3984_3987dupGTCA and MSH6*c.3959_3962delCAAG cause Lynch syndrome and are founder mutations in Ashkenazi Jews. Together with other AJ founder mutations, they contribute substantially to the incidence of CRC and EnCa and are important tools for the early diagnosis and appropriate management of AJ Lynch syndrome patients.

On the origin and diffusion of BRCA1 c.5266dupC (5382insC) in European populations

The BRCA1 mutation c.5266dupC was originally described as a founder mutation in the Ashkenazi Jewish (AJ) population. However, this mutation is also present at appreciable frequency in several European countries, which raises intriguing questions about the origins of the mutation. We genotyped 245 carrier families from 14 different population groups (Russian, Latvian, Ukrainian, Czech, Slovak, Polish, Danish, Dutch, French, German, Italian, Greek, Brazilian and AJ) for seven microsatellite markers and confirmed that all mutation carriers share a common haplotype from a single founder individual. Using a maximum likelihood method that allows for both recombination and mutational events of marker loci, we estimated that the mutation arose some 1800 years ago in either Scandinavia or what is now northern Russia and subsequently spread to the various populations we genotyped during the following centuries, including the AJ population. Age estimates and the molecular evolution profile of the most common linked haplotype in the carrier populations studied further suggest that c.5266dupC likely entered the AJ gene pool in Poland approximately 400-500 years ago. Our results illustrate that (1) BRCA1 c.5266dupC originated from a single common ancestor and was a common European mutation long before becoming an AJ founder mutation and (2) the mutation is likely present in many additional European countries where genetic screening of BRCA1 may not yet be common practice.

Synthetic lethal approaches to breast cancer therapy

The promise of personalized therapy for breast cancer is that therapeutic efficacy will be increased while toxic effects are reduced to a minimum. To achieve this goal, there is now an emphasis on the design of therapies that are based not only on the clinical manifestations of the disease, but also on the underlying molecular and cellular biology of cancer. However, identifying targets for personalized therapies in breast cancer is challenging. Here, we describe how biological concepts such as synthetic lethality and oncogene addiction can be used to identify new therapeutic targets and approaches. We discuss the current clinical developments in implementing synthetic lethality therapies, and highlight new ways in which this approach could be used to target specific subsets of breast cancer.

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

BACKGROUND

The frequency and characteristics of disease in individuals who concomitantly harbor pathogenic mutations in both BRCA1 and BRCA2 genes are not established.

MATERIALS AND METHODS

Data 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.

RESULTS

In 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.

CONCLUSION

Double 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.

Hereditary ovarian cancer: biology, response to chemotherapy and prognosis

Recent evidence has indicated that the prognosis of women with epithelial ovarian cancer who are BRCA-mutation carriers may be better than for noncarriers. Part of the explanation is a higher sensitivity to platinum and other chemotherapies, as was demonstrated in in vitro studies, as well as a possible different biology. BRCA genes are important in double-strand DNA break repair and in other important processes of the cell cycle. Mutation or reduced activity of BRCA genes leads to a higher vulnerability to DNA damage (caused by chemotherapy and radiotherapy) compared with malignant tumors of noncarriers. New targeted drugs, such as poly (ADP-ribose) polymerase-1 and -2 inhibitors, are currently under investigation, as are new biomarkers that will hopefully lead the way to better treatment and longer survival. Testing for the BRCA mutation should be carried out and used as a guide for therapy in most patients with epithelial ovarian cancer.

Hereditary breast and ovarian cancer due to mutations in BRCA1 and BRCA2

Hereditary breast and ovarian cancer due to mutations in the BRCA1 and BRCA2 genes is the most common cause of hereditary forms of both breast and ovarian cancer. The overall prevalence of BRCA1/2 mutations is estimated to be from 1 in 400 to 1 in 800 with a higher prevalence in the Ashkenazi Jewish population (1 in 40). Estimates of penetrance (cancer risk) vary considerably depending on the context in which they were derived and have been shown to vary within families with the same BRCA1/2 mutation. This suggests there is no exact risk estimate that can be applied to all individuals with a BRCA1/2 mutation. The likelihood of harboring a BRCA1 or BRCA2 mutation is dependent on one's personal and/or family history of cancer and can be estimated using various mutation probability models. For those individuals who have a BRCA1 or BRCA2 mutation, several screening and primary prevention options have been suggested, including prophylactic surgery and chemoprevention. Once a BRCA1 or BRCA2 mutation has been identified in a family, testing of at-risk relatives can identify those family members who also have the familial mutation and thus need increased surveillance and early intervention when a cancer is diagnosed.

Global patterns of cancer incidence and mortality rates and trends

While incidence and mortality rates for most cancers (including lung, colorectum, female breast, and prostate) are decreasing in the United States and many other western countries, they are increasing in several less developed and economically transitioning countries because of adoption of unhealthy western lifestyles such as smoking and physical inactivity and consumption of calorie-dense food. Indeed, the rates for lung and colon cancers in a few of these countries have already surpassed those in the United States and other western countries. Most developing countries also continue to be disproportionately affected by cancers related to infectious agents, such as cervix, liver, and stomach cancers. The proportion of new cancer cases diagnosed in less developed countries is projected to increase from about 56% of the world total in 2008 to more than 60% in 2030 because of the increasing trends in cancer rates and expected increases in life expectancy and growth of the population. In this review, we describe these changing global incidence and mortality patterns for select common cancers and the opportunities for cancer prevention in developing countries.

Founder BRCA1/2 mutations in the Europe: implications for hereditary breast-ovarian cancer prevention and control

Detection of mutations in hereditary breast and ovarian cancer-related BRCA1 and BRCA2 genes is an effective method of cancer prevention and early detection. Different ethnic and geographical regions have different BRCA1 and BRCA2 mutation spectrum and prevalence. Along with the emerging targeted therapy, demand and uptake for rapid BRCA1/2 mutations testing will increase in a near future. However, current patients selection and genetic testing strategies in most countries impose significant lag in this practice. The knowledge of the genetic structure of particular populations is important for the developing of effective screening protocol and may provide more efficient approach for the individualization of genetic testing. Elucidating of founder effect in BRCA1/2 genes can have an impact on the management of hereditary cancer families on a national and international healthcare system level, making genetic testing more affordable and cost-effective. The purpose of this review is to summarize current evidence about the BRCA1/2 founder mutations diversity in European populations.

Identification of a novel BRCA1 nucleotide 4803delCC/c.4684delCC mutation and a nucleotide 249T>A/c.130T>A (p.Cys44Ser) mutation in two Greenlandic Inuit families: implications for genetic screening of Greenlandic Inuit families with high risk for breast and/or ovarian cancer

Germ-line mutations in the tumour suppressor proteins BRCA1 and BRCA2 predispose to breast and ovarian cancer. We have recently identified a Greenlandic Inuit BRCA1 nucleotide 234T>G/c.115T>G (p.Cys39Gly) founder mutation, which at that time was the only disease-causing BRCA1/BRCA2 mutation identified in this population. Here, we describe the identification of a novel disease-causing BRCA1 nucleotide 4803delCC/c.4684delCC mutation in a Greenlandic Inuit with ovarian cancer. The mutation introduces a frameshift and a premature stop at codon 1572. We have also identified a BRCA1 nucleotide 249T>A/c.130T>A (p.Cys44Ser) mutation in another Greenlandic individual with ovarian cancer. This patient share a 1-2 Mb genomic fragment, containing the BRCA1 gene, with four Danish families harbouring the same mutation, suggesting that the 249T>A/c.130T>A (p.Cys44Ser) mutation originates from a Danish ancestor. We conclude that screening of Greenlandic Inuits with high risk of breast or ovarian cancer should include sequencing of the entire BRCA1 gene.

Impact of BRCA mutations on female fertility and offspring sex ratio

Positive selection for inherited mutations in breast and ovarian cancer predisposing genes, BRCA1 and BRCA2, may contribute to the high frequency of BRCA mutations among the Ashkenazi Jewish population. Impact of BRCA mutations on fertility has not been generally explored in epidemiologic studies. There are reports of distorted sex ratios in BRCA carrier families but these findings have been attributed to bias. We investigated the effect of BRCA mutations on female fertility and offspring sex ratio in a study of 260 Ashkenazi Jewish women with ovarian cancer and 331 controls, unselected for age or family history of the disease. Pregnancy success was similar for 96 mutation carrier (0.84) and 164 noncarrier cases (0.87) and controls (0.83). After adjusting for covariates, there were no significant differences between BRCA carrier and noncarrier cases and controls with regards to fertility, despite lower pregnancy rates among all cases compared to controls (P = 0.0049). Male/female sex ratios were significantly lower among offspring of carriers (0.71) than offspring of noncarriers (0.95) or those of the controls (0.99). Comparisons among the three groups yielded statistically significant distortion against males among the offspring of known and obligate BRCA carriers compared to noncarriers (OR = 0.74, 95% CI:0.55-0.99) and controls (OR = 0.71, 95% CI:0.54-0.94). In conclusion, we did not find evidence for an effect of BRCA mutations on female fertility. We found a significant excess of females among the offspring of female carriers of BRCA1 and BRCA2 mutations. Potential contribution of observed sex ratio distortions to positive selection for BRCA mutations may warrant further investigation.

Assessing women at high risk of breast cancer: a review of risk assessment models

Women who are at high risk of breast cancer can be offered more intensive surveillance or prophylactic measures, such as surgery or chemoprevention. Central to decisions regarding the level of prevention is accurate and individualized risk assessment. This review aims to distill the diverse literature and provide practicing clinicians with an overview of the available risk assessment methods. Risk assessments fall into two groups: the risk of carrying a mutation in a high-risk gene such as BRCA1 or BRCA2 and the risk of developing breast cancer with or without such a mutation. Knowledge of breast cancer risks, taken together with the risks and benefits of the intervention, is needed to choose an appropriate disease management strategy. A number of models have been developed for assessing these risks, but independent validation of such models has produced variable results. Some models are able to predict both mutation carriage risks and breast cancer risk; however, to date, all are limited by only moderate discriminatory accuracy. Further improvements in the knowledge of how to best integrate both new risk factors and newly discovered genetic variants into these models will allow clinicians to more accurately determine which women are most likely to develop breast cancer. These steady and incremental improvements in models will need to undergo revalidation.

Detailed haplotype analysis at the TP53 locus in p.R337H mutation carriers in the population of Southern Brazil: evidence for a founder effect

Due to patterns of migration, selection, and population expansion, founder effects are common among humans. In Southern Brazil, a recurrent TP53 mutation, p.R337H, is detected in families with cancer predisposition. We have used whole locus resequencing and high-density single nucleotide polymorphism (SNP) genotyping to refine TP53 locus haplotype definitions. Haplotyping of 12 unrelated p.R337H carriers using a set of 29 tag SNPs, revealed that all subjects carried the same haplotype, and presence of the mutation on this haplotype was confirmed by allele-specific PCR. The probability that this haplotype occurs independently in all index cases was of 3.1x10(-9), demonstrating a founder effect. Analysis of the patterns of 103 tumors diagnosed in 12 families showed that the presence of p.R337H is associated with multiple cancers of the Li-Fraumeni Syndrome (LFS) spectrum, with relatively low penetrance before the age of 30 but a lifetime risk comparable to classical LFS. The p.R337H families are mostly distributed along a road axis historically known as the main route used by merchants of Portuguese origin in the XVIII and XIX century. This historical circumstance and the relatively low penetrance before the age of 30 may have contributed to the maintenance of this pathogenic mutation in a large, open population.

Distress among women receiving uninformative BRCA1/2 results: 12-month outcomes

OBJECTIVE

Few data are available regarding the long-term psychological impact of uninformative BRCA1/2 test results. This study examines change in distress from pretesting to 12-months post-disclosure, with medical, family history, and psychological variables, such as pretesting perceived risk of carrying a deleterious mutation prior to testing and primary and secondary appraisals, as predictors.

METHODS

Two hundred and nine women with uninformative BRCA1/2 test results completed questionnaires at pretesting and 1-, 6-, and 12-month post-disclosure, including measures of anxiety and depression, cancer-specific and genetic testing distress. We used a mixed models approach to predict change in post-disclosure distress.

RESULTS

Distress declined from pretesting to 1-month post-disclosure, but remained stable thereafter. Primary appraisals predicted all types of distress at 1-month post-disclosure. Primary and secondary appraisals predicted genetic testing distress at 1-month as well as change over time. Receiving a variant of uncertain clinical significance and entering testing with a high expectation for carrying a deleterious mutation predicted genetic testing distress that persisted through the year after testing.

CONCLUSIONS

As a whole, women receiving uninformative BRCA1/2 test results are a resilient group. For some women, distress experienced in the month after testing does not dissipate. Variables, such as heightened pretesting perceived risk and cognitive appraisals, predict greater likelihood for sustained distress in this group and could be amenable to intervention.

Exploring perceptions of genetic testing: an examination of perceived accuracy over time

OBJECTIVE

Despite the potential impact of perceptions of genetic testing, little research has examined these perceptions. The current study examined factors associated with perceived accuracy of genetic testing to detect BRCA1/2 mutations and change in perceived accuracy.

METHODS

Participants were recruited through advertisements, community groups, and local oncologists and gynecologists. Ashkenazi Jewish patients (N=120) at increased risk for BRCA1/2 genetic mutations were surveyed in a repeated-measures design with assessments at three time points: pre-counseling, post-counseling, and post-testing.

RESULTS

Better knowledge of cancer genetics related to higher perceived accuracy before counseling. Lower perceived risk of developing ovarian cancer was associated with increased perceived accuracy, while greater distress regarding gene status was associated with decreased perceived accuracy. Genetic test results were unrelated to change in perceived accuracy.

CONCLUSION

The results offer an initial look at how patients form perceptions of genetic testing. Both cognitive factors and affective factors relate to how patients perceived the accuracy of testing and how their perception changes over time.

PRACTICE IMPLICATIONS

Understanding cognitive and affective factors which may impact patients' perceptions of genetic testing is important. Specifically, attention should be paid to educating patients regarding cancer genetics and encouraging adaptive coping strategies to deal with distress.

The identification of colon cancer susceptibility genes by using genome-wide scans

Recent studies have indicated that in approximately 35% of all colorectal cancer (CRC) cases, the CRC was inherited. Although a number of high-risk familial variants have been identified, these mutations explain <6% of CRC cases; therefore, further genome-wide scans will need to be conducted in the future. There are two popular approaches to genome-wide scans, namely linkage and association. The linkage approach utilizes several hundred markers (typically between 300 and 500 markers) throughout the genome and identifies candidate regions shared among affected family members. Candidate regions are then scrutinized for the presence of susceptibility loci. Linkage studies require no prior information and can provide new avenues for future research, but the regions identified are often large and include many candidate genes. The second and more recent approach is the genome-wide association study (GWAS) in which hundreds of thousands of markers called single nucleotide polymorphisms (SNPs) are used to identify the SNPs associated with traits of interest by employing family-based or case-control association methods. GWAS studies require no prior information and, because they use hundreds of thousands of SNPs, they can target specific candidate genes and/or narrow regions for investigation. Study design considerations, methodology, and the execution of linkage and genome-wide association studies that use both family and case-control designs are covered in this chapter.

Screening for founder mutations in BRCA1 and BRCA2 in unselected Jewish women

PURPOSE

There are two mutations in BRCA1 and one mutation in BRCA2 that are present in up to 2.5% of Ashkenazi Jewish women. Current guidelines for testing stipulate that a personal or family history of cancer be present to be eligible for testing. To date, population screening in this population has not been suggested. However, this may be rational. Little is known about the appropriateness of testing guidelines for the Jewish population or the level of interest in testing.

METHODS

Eligible subjects were women who self-identified as Jewish, who were between the ages of 25 and 80 years, and who resided in Ontario. Subjects were recruited through an article in a national newspaper. Women were asked to complete a study questionnaire and a family history questionnaire and to provide a blood or saliva sample. The risk of carrying a BRCA mutation was estimated for each woman. Results A total of 2,080 women were enrolled onto the study. The overall mutation prevalence was 1.1% (0.5% for BRCA1 and 0.6% for BRCA2). Among the 22 mutation carriers, the mean estimate of carrying a BRCA mutation was 3.9%. Ten (45%) of the 22 women met the current Ontario Ministry of Health Guidelines criteria for testing.

CONCLUSION

There is considerable interest for genetic testing among Jewish women at low risk of carrying a mutation. However, many women with mutations are ineligible for genetic testing under current guidelines. Approximately 1% of Jewish women carry a BRCA mutation, and these women should be considered to be candidates for genetic testing.

BRCA1 185delAG mutant protein, BRAt, up-regulates maspin in ovarian epithelial cells

OBJECTIVE

Aggressive clinical course and difficult detection of ovarian cancer are major challenges to improving patient survival and necessitate avid investigation into more effective therapeutic approaches. Understanding early molecular and pathological changes in high risk patients, such as BRCA1 mutation carriers, can provide candidates for molecular profiling and novel targets for effective therapies.

METHODS

Using a culture model system for normal human ovarian surface epithelial cells with and without the BRCA1 185delAG frameshift mutation for the truncated protein product, BRAt, we investigated the role of BRAt in enhanced chemosensitivity. We used MTS, Western immunoblot, semi-quantitative RT-PCR, luciferase reporter and siRNA assays, to identify novel downstream targets of BRAt that promote apoptosis following chemotherapeutic treatment.

RESULTS

We identified maspin as a novel downstream target of BRAt. BRAt increases maspin expression with preferential nuclear localization of maspin. Further, Brat-mediated maspin expression is transcriptionally regulated through an AP1 site within the (-520) to (-297) region of the promoter. Lastly, BRAt, enhances chemosensitivity in normal ovarian surface epithelial cells through c-Jun by a mechanism that may involve maspin.

CONCLUSIONS

BRAt-mediated enhanced chemosensitivity correlates clinically with enhanced chemotherapeutic response in BRCA1 mutation carriers. BRAt-mediated maspin expression also correlates with improved prognostic outlook for ovarian tumors with high levels of nuclear maspin. Consequently, understanding early genotypic and phenotypic changes in the context of high risk disease may provide a better understanding of the mechanism of mutation-associated ovarian cancer and provide new targets for therapeutic intervention.

Haplotype of the C61G BRCA1 mutation in Polish and Jewish individuals

Recurring mutations in the BRCA1 gene are noted in some populations and represent either founder mutations or a mutational hot spot. The C61G*BRCA1 (c.181T>G) missense mutation is a pathogenic one commonly reported in Polish individuals. A Jewish non-Ashkenazi family (of Italian ancestry) was found to carry this mutation, and the present study aimed at evaluating whether this mutation represents a founder mutation or a mutational hot spot. To that end, multilocus allelotyping using five markers intragenic to and flanking the BRCA1 gene spanning a genomic region of approximately 1.5 Mbp was carried out in that family and in 20 unrelated Polish C61G*BRCA1 mutation carriers. Phasing was done using affected and unaffected Jewish family members. The alleles that compose the pathogenic, mutation-carrying intragenic BRCA1 haplotype of the Jewish mutation carriers were detected in 18/20 Polish mutation carriers. The two flanking markers farthest away showed more diversity, between and even within Polish individuals. In conclusion, the *BRCA1 missense mutation is a founder mutation that can be detected in geographically related populations.

Screening and prevention of breast cancer in primary care

Mammography remains the mainstay of breast cancer screening. There is little controversy that mammography reduces the risk of dying from breast cancer by about 23% among women between the ages of 50 and 69 years, although the harms associated with false-positive results and overdiagnosis limit the net benefit of mammography. Women in their 70s may have a small benefit from screening mammography, but overdiagnosis increases in this age group as do competing causes of death. While new data support a 16% reduction in breast cancer mortality for 40- to 49-year-old women after 10 years of screening, the net benefit is less compelling in part because of the lower incidence of breast cancer in this age group and because mammography is less sensitive and specific in women younger than 50 years. Digital mammography is more sensitive than film mammography in young women with similar specificity, but no improvements in breast cancer outcomes have been demonstrated. Magnetic resonance imaging may benefit the highest risk women. Randomized trials suggest that self-breast examination does more harm than good. Primary prevention with currently approved medications will have a negligible effect on breast cancer incidence. Public health efforts aimed at increasing mammography screening rates, promoting regular exercise in all women, maintaining a healthy weight, limiting alcohol intake, and limiting postmenopausal hormone therapy may help to continue the recent trend of lower breast cancer incidence and mortality among American women.

Development and characterization of reference materials for MTHFR, SERPINA1, RET, BRCA1, and BRCA2 genetic testing

Well-characterized reference materials (RMs) are integral in maintaining clinical laboratory quality assurance for genetic testing. These RMs can be used for quality control, monitoring of test performance, test validation, and proficiency testing of DNA-based genetic tests. To address the need for such materials, the Centers for Disease Control and Prevention established the Genetic Testing Reference Material Coordination Program (GeT-RM), which works with the genetics community to improve public availability of characterized RMs for genetic testing. To date, the GeT-RM program has coordinated the characterization of publicly available genomic DNA RMs for a number of disorders, including cystic fibrosis, Huntington disease, fragile X, and several genetic conditions with relatively high prevalence in the Ashkenazi Jewish population. Genotypic information about a number of other cell lines has been collected and is also available. The present study includes the development and commutability/genotype characterization of 10 DNA samples for clinically relevant mutations or sequence variants in the following genes: MTHFR; SERPINA1; RET; BRCA1; and BRCA2. DNA samples were analyzed by 19 clinical genetic laboratories using a variety of assays and technology platforms. Concordance was 100% for all samples, with no differences observed between laboratories using different methods. All DNA samples are available from Coriell Cell Repositories and characterization information can be found on the GeT-RM website.

Haplotypes of the I157T CHEK2 germline mutation in ethnically diverse populations

The CHEK2*I157T missense mutation, reported in ethnically diverse, high-risk families, moderately increases breast and colon cancer risk. The present study assessed whether this mutation represents a founder mutation. Participants identified in high risk clinics or from consecutive cancer patients in Israel, Poland, Latvia, and Finland, were either carriers of the CHEK2*I157T mutation or non-carrier family members. Multi-locus genotyping employed two intragenic markers and five CHEK2 gene flanking markers, spanning about 645 kb. Haplotyping was done when families were available for phasing. Overall, 101 individuals (83 I157T*CHEK2 mutation carriers) were genotyped: 16 Finnish individuals from 11 families (14 mutation carriers, two non-carrier family members), 50 Polish individuals (20 families) (35 carriers, 15 non-carriers), 28 unrelated Latvian mutation carriers, and seven Israeli participants (two families) (six mutation carriers, one non-carrier). Overall 36/83 mutation carriers (43%) were diagnosed with breast cancer, 15/83 (18%)-colon cancer, three-ovarian cancer, one-thyroid cancer, and the rest (n = 28) were asymptomatic. A common core haplotype was detected in all I157T*CHEK2 mutation carriers of Israeli, Polish, and Finnish origin between markers D22S275-D22S689 (approximately 258 kb), with a different allele pattern in Latvians. In conclusion, CHEK2*I157T missense mutation is a founder mutation in ethnically diverse populations, but may also be a mutational hotspot.

A high frequent BRCA1 founder mutation identified in the Greenlandic population

Approximately 10% of all breast and ovarian cancers are dominantly inherited and mutations are mainly found in the BRCA 1 and 2 genes. The penetrance of BRCA1 mutations is reported to be between 68 and 92% and confers a 36-92% life time risk of breast cancer. Most mutations in BRCA1 are uniquely occurring mutations, but founder mutations have been described. In this study we describe a founder mutation with wide spread presence in the Inuit population. We have screened 2,869 persons from Greenland for the presence of a BRCA1 mutation (p.Cys39Gly) only found in the Inuit population. The overall carrier frequency was 1.6% in the general population, but the frequency differs geographically from 0.6% on the West coast to 9.7% in the previously isolated population of the East coast. This is to our knowledge the highest population frequency of a BRCA1 mutation ever to be described. To determine the clinical relevance of the mutation, we have examined ten breast cancer patients and nine ovarian cancer patients from Greenland for the presence of the p.Cys39Gly mutation. We found three ovarian cancer patients (33%) and one breast cancer patient (10%) carrying the mutation. The high number of women carrying a BRCA1 mutation known to trigger the development of potentially lethal diseases leads us to recommend an offer of genetic counselling and test for the mutation to all females of Inuit origin, thereby hopefully preventing a number of breast and ovarian cancer deaths.

Survey of unaffected BRCA and mismatch repair (MMR) mutation positive individuals

Many individuals do not proceed with cancer predisposition testing due to fears of genetic discrimination (GD). We report the results of a survey of 47 unaffected, mutation positive individuals regarding insurance outcomes. Participants recruited from six different Cancer Risk Programs across the country were queried about their experiences with health, life, and disability insurance, as well as employment issues. Eighty-seven percent of participants carried a BRCA mutation and 87% were part of a group insurance plan at the time of testing. Forty-seven percent of participants self-paid for testing. Less than 10% of participants reported that their results were placed in the general medical record, while 43% did not know where their results were placed. Due to concerns about GD, 13% of participants stated they avoided changing jobs. Thirteen percent stated that their at-risk relatives had not undergone testing for the familial mutation due to fears about GD. Adverse events following genetic testing included two denials from private health insurers, one denial for average life insurance coverage and one denial for additional disability insurance. There were no reports of job discrimination. Results suggest fear of GD is prevalent, yet data do not support evidence that GD exists.

Familial pancreatic cancer

CONTEXT

Approximately 5% to 10% of individuals with pancreatic cancer report a history of pancreatic cancer in a close family member. In addition, several known genetic syndromes, such as familial breast cancer (BRCA2), the Peutz-Jeghers syndrome, and the familial atypical multiple mole melanoma syndrome, have been shown to be associated with an increased risk of pancreatic cancer. The known genes associated with these conditions can explain only a portion of the clustering of pancreatic cancer in families, and research to identify additional susceptibility genes is ongoing.

OBJECTIVE

To provide an understanding of familial pancreatic cancer and the pathology of familial exocrine pancreatic cancers.

DATA SOURCES

Published literature on familial aggregation of pancreatic cancer and familial exocrine pancreatic tumors.

CONCLUSIONS

Even in the absence of predictive genetic testing, the collection of a careful, detailed family history is an important step in the management of all patients with pancreatic cancer. While most pancreatic cancers that arise in patients with a family history are ductal adenocarcinomas, certain subtypes of pancreatic cancer have been associated with familial syndromes. Therefore, the histologic appearance of the pancreatic cancer itself, and/or the presence and appearance of precancerous changes in the pancreas, may increase the clinical index of suspicion for a genetic syndrome.

Familial pancreatic cancer

CONTEXT

Approximately 5% to 10% of individuals with pancreatic cancer report a history of pancreatic cancer in a close family member. In addition, several known genetic syndromes, such as familial breast cancer (BRCA2), the Peutz-Jeghers syndrome, and the familial atypical multiple mole melanoma syndrome, have been shown to be associated with an increased risk of pancreatic cancer. The known genes associated with these conditions can explain only a portion of the clustering of pancreatic cancer in families, and research to identify additional susceptibility genes is ongoing.

OBJECTIVE

To provide an understanding of familial pancreatic cancer and the pathology of familial exocrine pancreatic cancers.

DATA SOURCES

Published literature on familial aggregation of pancreatic cancer and familial exocrine pancreatic tumors.

CONCLUSIONS

Even in the absence of predictive genetic testing, the collection of a careful, detailed family history is an important step in the management of all patients with pancreatic cancer. While most pancreatic cancers that arise in patients with a family history are ductal adenocarcinomas, certain subtypes of pancreatic cancer have been associated with familial syndromes. Therefore, the histologic appearance of the pancreatic cancer itself, and/or the presence and appearance of precancerous changes in the pancreas, may increase the clinical index of suspicion for a genetic syndrome.

The recognition and surgical management of heritable lesions of the pancreas

Our knowledge regarding the inherited factors that lead to the development of lesions within the pancreas is clearly incomplete. This article addresses clinical issues in patients at moderate-to-high risk for pancreatic malignancy, with special emphasis on the recognition and diagnosis of known genetic syndromes. Using the current available information, the authors attempt to equip the practicing surgeon with critical information to increase clinical suspicion for heritable syndromes and inform specific surgical management. Additionally, this article is meant to encourage the practicing surgeon to participate in the genetic testing/screening, cancer surveillance, and prevention activities of patients who have heritable cancer syndromes and associated pancreatic lesions that require surgery.

A screening and prevention programme serving an ethnically diverse population of women at high risk of developing breast and/or ovarian cancer

INTRODUCTION

We describe a screening and prevention programme primarily targeting under-served minority women at high risk of breast and/or ovarian cancer. Women attending this Bellevue Hospital Center (BHC) Clinic were either self-referred from a variety of special outreach programmes or referred internally by medical professionals caring for relatives or friends. Our objective was to delineate referral sources and preliminary risk-assessment findings in relation to demographic features in this population.

METHODS

Following a detailed family and personal history intake and physical examination, each woman on her initial visit is categorized into a low (standard) risk, high-risk or indeterminate-risk group. Women found to be at high risk of developing breast and/or ovarian cancers are referred for further testing, additional screening measures, or participation in chemoprevention trials. All other women are counselled concerning follow-up and lifestyle issues.

RESULT

Between 2003 and 2007, 171 women for whom complete information was obtained were analysed. Thirty-four of the women were Caucasians (19.8%) and 137 (80.2%) were ethnically diverse minority women. Sixty-two (36.2%) were found to be at high risk with a median age of 42 years. The majority of the high-risk women were referred to the clinic by medical professionals (58%), most of whom were from within the BHC health care system. In fact, one-fourth of the referrals were women who carried a diagnosis of cancer, mostly arising in the breast, and who were concerned with risks to other family members. Trends in genetic testing results indicate fewer mutations among high-risk Asians than among other ethnicities.

CONCLUSION

Accurate risk assessments and implementation of screening and prevention measures have been challenging during the first few years of operation. Nevertheless, the need for providing consultation from internal referrals and the potential for genetic and psychosocial research in an ethnically diverse population are powerful incentives for continuing to evolve these services.

Polymorphisms in BRCA2 resulting in aberrant codon-usage and their analysis on familial breast cancer risk

Mutations in BRCA1 and BRCA2 are associated with increased breast cancer risk. While numerous non-synonymous SNPs in BRCA1/2 have been investigated for breast cancer risk, the impact of synonymous SNPs has not been studied so far. Recently, it has been reported that synonymous SNPs leading to an aberration from the preferred codon-usage can have functional effects and consequently be associated with disease. This motivated us to search for SNPs with the tendency to differential codon-usage in BRCA1/BRCA2. Based on defined criteria, two codon-usage-changing variants, Ser455Ser (1365A > G) and Ser2414Ser (7242A > G), were detected in BRCA2, whereas no such variant could be identified in BRCA1. We investigated the impact of these variants on breast cancer risk in a large case-control study. However, both SNPs, BRCA2 Ser2414Ser (7242A > G) and Ser455Ser (1365A > G), showed no association with breast cancer risk. This indicates that these codon-usage-changing SNPs have no major impact on familial breast cancer risk.