Breast cancer genetics Unsolved questions and open perspectives in an expanding clinical practice.код для вставкиСкачать
American Journal of Medical Genetics Part C (Semin. Med. Genet.) 129C:56 –64 (2004) A R T I C L E Breast Cancer Genetics: Unsolved Questions and Open Perspectives in an Expanding Clinical Practice SHIRLEY V. HODGSON,* PATRICK J. MORRISON, AND MELITA IRVING Breast cancer is the most common cause of cancer death in the United Kingdom, with a lifetime risk of one in nine in women. Only 5–10% of all cancers is thought to be due to strongly penetrant inherited predisposing genes, such as BRCA1 and BRCA2. However, other less penetrant genes, including some autosomal recessive genes, are likely to be of etiological importance in other families. This review addresses the current knowledge of breast cancer susceptibility genes and explores the possibilities for future developments. Features of tumor pathology, prognosis, and the scope for targeted treatments in mutation carriers are discussed, and the management of known carriers and those at increased risk for developing breast cancer are evaluated. Genetic testing for cancer susceptibility may become widely available in the future, and has important ethical and management implications. ß 2004 Wiley-Liss, Inc. KEY WORDS: BRCA1; BRCA2; breast cancer INTRODUCTION Breast cancer is the most common cause of cancer death in the United Kingdom (lifetime risk one in nine in women) [National Statistics Cancer Registrations in England, 2000] (www.statistics.gov.uk), with increasing prevalence. A recognized risk factor for breast cancer is a birth date later than 1930. Population studies of immigrants find that they acquire the level of cancer risk of the host countries. Hormonal influences associated with estrogen exposure (e.g., age at menarche, contraceptive pill usage, pregnancies) are important in determining breast cancer risk [Colditz, 1998], and dietary (e.g., saturated fat intake) and other environmental factors may also play a part [Bingham et al., 2003]. Their identification should be a priority to develop strategies for disease prevention. Familial clustering of breast cancer has been well documented, with relative risks increasing as the age at diagnosis is younger or the family history more extensive. Overall, however, only 5–10% of all breast cancers are thought to be due to strongly penetrant inherited predisposing mutations in genes such as BRCA1 and BRCA2 [Claus et al., 1991; Pharoah Professor Shirley Hodgson is Professor of Cancer Genetics at St. George’s Hospital, London. She has been working in the field of cancer genetics since 1988, and has helped to develop cancer genetics clinical services in several UK clinics (notably Guy’s and St. Mark’s Hospitals in London). She has also been involved in translational research into the inherited aspects of cancer, particularly colorectal and breast cancer. She was instrumental in initiating the British Familial Cancer Record, a database for follow-up of familial cancer families in several cancer genetics clinic in the UK; these have now become the clinical cancer genetics network of Cancer-Research-UK funded clinics. She is the co-author of several books on inherited cancer. Professor Patrick Morrison is a consultant clinical geneticist with a special interest in cancer genetics, in the Northern Ireland Regional Genetics Service, Belfast. He has published over 120 peerreviewed articles on all aspects of genetics, particularly late onset diseases, familial cancers, and insurance issues. He is currently co-writing a genetics textbook for surgeons and has co-authored (with Prof. Neva Haites and Prof. Shirley Hodgson) a book on familial breast and ovarian cancer. Dr. Melita Irving is a specialist registrar in clinical genetics, currently training at St. George’s Hospital, London. *Correspondence to: Shirley V. Hodgson, Professor of Cancer Genetics, Department of Clinical Development Sciences, St. George’s Hospital Medical School, Cranmer Terrace, London, UK SW19 0RE. E-mail: email@example.com DOI 10.1002/ajmg.c.30019 ß 2004 Wiley-Liss, Inc. et al., 2002; Antoniou et al., 2003]. The majority of multicase families with both breast and ovarian cancers are due to inherited BRCA1 mutations, whereas those in families that include male breast cancer cases are more often due to BRCA2 mutations. However, in many families with four or five cases of breast cancer, without the above features, the cancers are not due to mutations in these genes. A hypothetical ‘‘BRCA3’’ gene has been invoked as a cause for these cancers. Multiple, lower-penetrance, Multiple, lower-penetrance, higher-frequency genes (including some autosomal recessive genes), are likely to make a significant contribution to this unexplained familial risk. higher-frequency genes (including some autosomal recessive genes), are likely to make a significant contribution to this unexplained familial risk [Dong and Hemminki, 2001; Chenevix-Trench et al., 2002]. ARTICLE KNOWN GENES INVOLVED BRCA1 is located on chromosome 17q [Miki et al., 1994] and has 22 exons, encoding 1,863 amino acids; BRCA2 [Wooster et al., 1995], lies on chromosome 13q and codes for a protein of 3,418 amino acids. Deleterious mutations are found throughout both genes and tend to be truncating. Polymorphisms of unclear significance are also found; improved methods of determining their pathogenicity include the use of RT-PCR and analysis of gene transcripts [Couch and Weber, 1996; Dunning et al., 1997; Claes et al., 2003]. Three common founder mutations are present in some populations, notably the Ashkenazi Jewish (ancestral) mutations in BRCA1 [Shattuck-Eidens et al., 1997] and BRCA2 [Abeliovich et al., 1997], which overall occur in up to 2% of the Ashkenazi population, and the Icelandic common mutation in BRCA2 [Thorlacius et al., 1996]. In these populations, specific assays are used to detect these mutations. A common BRCA1 mutation, 2800delAA, is found mainly in Northern Ireland and the West of Scotland, showing the similar origins of populations from these areas, whereas the BRCA2 6503delTT mutation is found on the East coast of Scotland, suggesting that this may have been introduced by Viking raiders or Scandinavian fisherman [Scottish/Northern Irish BRCA1/BRCA2 Consortium, 2003]. Larger genomic deletions/duplications occur more often in BRCA1 than in BRCA2, and some are founder mutations; these require specific detection methods, since they would not normally be detected by sequencing. Mutations in BRCA1 and BRCA2 have a prevalence of 0.11% in the general UK population and account for approximately 60% of cases of familial breast cancer [Peto et al., 1999]. Both genes encode proteins involved in double-strand DNA repair, specifically in homologous recombination, a highly specific method of errorfree DNA repair. BRCA1 is also involved in apoptosis and cell-cycle control, and the effects of its deficiency are cell-cycle dependent [Welcsh et al., AMERICAN JOURNAL OF MEDICAL GENETICS (SEMIN. MED. GENET.) 2000]. BRCA1 has a RING-finger domain that is likely to be involved in protein interactions that could target proteins for degradation. Both BRCA1 and BRCA2 contain BRCT repeats and both interact with RAD51—this interaction being along most of the BRCA2 protein, but along only 5% of BRCA1 [Pellegrini et al., 2002; Shamoo, 2003]. Binding to RAD51 allows BRCA2 to reach sites of DNA breaks. BRCA1 is phosphorylated in response to DNA damage in an ATMdependent manner, and relocates to chromosomal regions of DNA replication. In cells with deficient BRCA1 and BRCA2 proteins, DNA repair proceeds by the more error-prone alternative repair pathways of nonhomologous end-joining. Transcriptional regulation may also be a function of BRCA1/2 by interaction with RNA Pol II and RNA helicase A [Welcsh et al., 2000]. Both proteins are normally nuclear and their mRNAs are preferentially expressed during late G1–early S phase of the cellcycle. Punctate foci of BRCA1, BRCA2, and RAD51 may be detected in the nucleus in S phase, and in meiotic cells they associate with unsynapsed regions of synaptonemal complexes. BRCA1 may regulate the G2-M checkpoint by controlling mitotic spindle assembly and thus chromosome segregation. Mice with homozygously deleted exon 11 of BRCA1 demonstrate chromosomal instability with aneuploidy and chromosome rearrangements. BRCA2 mutants are also deficient in spindle assembly checkpoints [Tutt and Ashworth, 2002; Venkitaraman, 2002; Anand et al., 2003]. None of the functions of BRCA1/2 appear to be specific to the breast tissue. The reason for the tissue specificity in cancer susceptibility is unclear, although the obvious involvement of estrogen target organs makes it likely that the secondary effects of gene mutation are enhanced by a tissue environment responsive to estrogens. FUTURE SCOPE: DOES BRCA3 EXIST? The search for a third high-penetrance gene, ‘‘BRCA3,’’ has been disap- 57 pointing to date. Researchers have utilized a variety of approaches, including linkage analysis, sib-pair analysis, and a combination of linkage and tumor expression profiling, to identify families with the same genetic phenotype [Lathrop et al., 1984; Hedenfalk et al., 2003]. Linkage data indicated a susceptibility locus on 13q21, but this was discounted by further studies in other populations [Kainu et al., 2000; Thompson et al., 2002], and a similar fate was met by other promising regions, e.g., 8p and 6q [Seitz et al., 1997]. These results tended to rule out single genes with large effects playing a major role as ‘‘BRCA3.’’ Recent segregation analysis in familial breast and ovarian cancer to find the best-fitting model showed that the majority of familial cases could be accounted for by BRCA1 or BRCA2 mutations, with a polygenic cause for the remaining cases. No evidence for a putative high-risk susceptibility gene, ‘‘BRCA3,’’ was found, although there was a case to be made for a possible contribution from recessive alleles [Antoniou et al., 2002]. Epidemiological analysis suggests that if BRCA1 and BRCA2 mutation carriers are excluded, approximately 12% of women have a roughly 10% risk of developing breast cancer by the age of 70, accounting for 50% of all cases of breast cancer, whereas about 50% of cases develop in women who have a much smaller risk of breast cancer (&3%) [Pharoah et al., 2002]. Peto [Peto and Mack, 2000; Peto, 2002] has argued that since women who have developed breast cancer have a constant annual risk of 1.7% of developing a second breast cancer, it can be postulated that all women with breast cancer have an inherited susceptibility to the disease, likely to be due to several genes of moderate effect. LOWER PENETRANCE GENES The challenge is to identify such lower penetrance genes. CHEK2 represents an example of a moderate effect gene. A common CHEK2 mutation (1100delC) occurs in approximately 1% of the general population [Meijers-Heijboer 58 AMERICAN JOURNAL OF MEDICAL GENETICS (SEMIN. MED. GENET.) et al., 2002], and in 3–6% of women with breast cancer. This mutation was detected in 12% of unselected bilateral breast cancer cases and 13.5% of families with a male breast cancer case, and may therefore confer a 2- and 10-fold increased risk of breast cancer in females and males, respectively. Other variations in CHEK2 do not seem to make a major contribution to breast cancer susceptibility [Schutte et al., 2003]. Epidemiological studies have previously shown an increased risk of breast cancer in close relatives of ataxia telangiectasia (AT) patients, and there is some evidence that certain missense mutations in ATM, the AT gene, occur with increased frequency in breast cancer families. Examples of such ATM mutations are: L1420F, whose frequency was found to be 4.8% in 13 familial breast cancer families versus 0% in controls; and IVS10-6T > G and 7271G > T, which may segregate with the disease [Stankovic et al., 1998; ChenevixTrench et al., 2002; Thorstenson et al., 2003]. Such mutations are thought to exert a dominant-negative effect [Bishop and Hopper, 1997; Gatti et al., 1999; Angele et al., 2000]. It is unclear whether other ATM mutations confer any increase in risk [Izatt et al., 1999]. Intriguingly, both ATM and CHEK2 interact in the BRCA1/2 DNA repair pathway. ATM is involved in phosphorylation of BRCA1 in response to radiation-induced DNA damage, and the FANC-D LL protein causes ubiquitination of BRCA1 on DNA damage by cross-linking agents. One of the genes that causes the autosomal recessive condition Fanconi anemia, FANC-D2, has now been shown to be BRCA2 [D’Andrea and Grompe, 2003; Venkitaraman, 2003]. A germline Polish founder mutation in the NBS1 gene (657del15), which causes the Nijmegen breakage syndrome, an AT-like condition, has been shown to occur with increased frequency in breast cancer cases, particularly in familial cases [Gorski et al., 2003]. Clearly, many other lower penetrance genes are also likely to be involved, and will be difficult to identify, because they are unlikely to segregate ARTICLE with breast cancer in conventional linkage studies. TUMOR PATHOLOGY OTHER KNOWN GENES INVOLVED There are distinct features of breast cancer tumor pathology in BRCA1 mutation carriers that are characteristic: notably, a high mitotic count, continuous pushing margins, and lymphocytic infiltrates. Three genetic conditions conferring a high risk of breast cancer are well described. Mutations in TP53, which encodes a cell cycle regulatory protein, cause Li-Fraumeni syndrome, characterized by early onset breast cancer in association with other childhood cancers, in particular sarcomas and brain tumors [Li, 1990; Vogelstein and Kinzler, 1992]. LiFraumeni p53 mutations are highly penetrant for early onset breast cancer but are a rare cause overall. Inherited mutations in PTEN cause Cowden syndrome [Li et al., 1997; Marsh et al., 1999], which is associated with an increased susceptibility to breast cancer. However, so far, this gene has not been involved in nonsyndromic breast cancer [Freihoff et al., 1999; Shugart et al., 1999]. Peutz-Jeghers syndrome, which is due to LKB1 mutations, is another rare cause of breast cancer in the general population [Boardman et al., 1998]. Common polymorphisms such as V1508M in the COMT gene, the CYP1A1 1462V variant, the short repeat sequence of the androgen receptor gene, and the transforming growth factor b1 gene (TGFb) (C-509T) are among those that have been calculated from large case–control studies to confer small, altered, relative risks of breast cancer [Rebbeck et al., 1999; Kuschel et al., 2002], but confirmation requires further studies in large cohorts of cases and controls. Variants in ATM, CHEK2, and RAD51, hormone receptors, cellcycle regulators, genes regulating nonhomologous end-joining, carcinogen metabolizing genes, and other factors, are also potential modifiers of breast cancer risk, although the evidence for such effects is still being accumulated. Polymorphisms in the second BRCA allele may play a part [Fu et al., 2003], and there is also good evidence for the influence of modifier gene variants on BRCA1/2 gene penetrance [Easton et al., 1995; Struewing et al., 1997; Fodor et al., 1998; Narod, 2002; Hartge, 2003]. There are distinct features of breast cancer tumor pathology in BRCA1 mutation carriers that are characteristic: notably, a high mitotic count, continuous pushing margins, and lymphocytic infiltrates. In addition, most BRCA1associated tumors are hormone receptor (ER and PgR) negative. In contrast, BRCA2-associated tumors resemble sporadic cancers in steroid receptor expression, but the histology tends to show poor tubule formation and continuous pushing margins without the other features of BRCA1 tumors. BRCA2 tumors show a higher frequency of p53 mutations and expression than sporadic cancers [Lakhani et al., 2002]. A basaloid ductal carcinoma phenotype may be more common in BRCA1 carrier tumors, with increased expression of basal cell keratins [Sorlie et al., 2001]; these cancers may be derived from stem cells that are CK5/ 6-positive and confer a poor prognosis [Foulkes et al., 2003]. Intriguingly, studies of gene expression profiles and comparative genomic hybridization (CGH) using cDNA microarrays in breast cancers from familial cases without germline BRCA1 or BRCA2 mutations show a multiplicity of different profiles, rather than a single ‘‘BRCA3’’ profile, further supporting the probability that the remainder of cases of familial breast cancer are due to several lower penetrance genes rather than a single ‘‘BRCA3’’ gene [Wessels et al., 2002; Hedenfalk et al., 2003]. BRCA1 and BRCA2 mutationassociated cancers, on the other hand, ARTICLE have very distinct and characteristic profiles. CGH on cDNA arrays and metaphase spreads in tumors from familial breast cancer cases may indicate the location of new breast cancer tumor suppressor genes [Hedenfalk et al., 2003; Ramus et al., 2003] and also show characteristic patterns of loss of heterozygosity in BRCA1 and BRCA2 carriers that can identify carriers with a very high accuracy (96%). Such arrays, and the use of gene expression profiles, may also be able to detect the ‘‘signatures’’ of goodand poor-prognosis breast cancers [Ma et al., 2003]. CLINICAL IMPLICATIONS Genetic Counseling and Risk Estimation A number of models have been derived for the evaluation of risk. The Gail risk evaluation model [Benichou et al., 1996] uses a number of factors, such as age at menarche, family history, and parity. The Claus model based on the Cancer and Steroid Hormone study derives risk [Claus et al., 1991] using a model of highly penetrant susceptibility genes. Pedigree factors that indicate the Pedigree factors that indicate the presence of a mutation in a susceptibility gene include multiple early onset (age <50 years) breast cancers in the family, breast and ovarian cancer in one relative, male breast cancer, and Ashkenazi Jewish ancestry. presence of a mutation in a susceptibility gene include multiple early onset (age <50 years) breast cancers in the family, breast and ovarian cancer in one relative, male breast cancer, and Ashkenazi Jewish ancestry [Lange et al., 1988; de la Hoya et al., 2003]. A molecular AMERICAN JOURNAL OF MEDICAL GENETICS (SEMIN. MED. GENET.) diagnosis makes predictive testing available to at-risk relatives. The estimated lifetime risk of breast cancer in BRCA1 and BRCA2 mutation carriers is similar for breast cancer (approximately 65%–80%), although the average age at diagnosis is slightly higher in BRCA2 carriers, and ovarian cancer risk is higher in BRCA1 (39%) than in BRCA2 (11%) mutation carriers. Estimates vary depending upon the mode of ascertainment [Antoniou et al., 2003]. The original Linkage Consortium data were obtained from multicase families, which may be enriched for high penetrance mutations [Ford et al., 1994], whereas population-based studies tend to give lower penetrance estimates. Different mutations in BRCA1 and BRCA2 are associated with different degrees of risk of ovarian cancer, and there are increased relative risks of other cancers, particularly prostate, pancreatic, and colorectal in BRCA2 carriers [Easton et al., 1995; Struewing et al., 1997; Fodor et al., 1998; Ford et al., 1998; Gayther et al., 2000; Risch et al., 2001; Gruber and Petersen, 2002; Thompson and Easton, 2002]. Screening Surveillance in women at moderate risk must be evaluated on a long-term basis. From 30–50% of women on surveillance diagnose their own cancers, and many are missed by mammography. However, there is evidence that cancers detected by mammography are detected earlier and have a better prognosis than those detected symptomatically. Recent trials of magnetic resonance imaging (MRI) suggest it is much more sensitive (100% for MRI vs. 44% for mammography) and more specific in detecting breast cancer, particularly in young women, because of their denser breast tissue [Kuhl et al., 2000; Lee et al., 2003]. MRI is clearly preferable in BRCA carriers, but expensive, and its usefulness in those at moderate risk is as yet not established. Nipple aspiration and ductal ultrasound methods are undergoing trials in high-risk women, but may not be acceptable for screening for breast cancer in those at moderate risk. The use 59 of proteomic pattern analysis in ductal lavage washings or nipple fluid aspirates, or in serum, is a new and promising diagnostic technique for identifying breast cancer early [Petricoin et al., 2002]. Treatment The question as to whether noncancerous cells of BRCA1 and BRCA2 carriers are more susceptible to Xirradiation and cross-linking agents is still unresolved, but has importance in terms of treatment for cancer in heterozygotes and screening by frequent mammography. The evidence so far is that radiosensitivity in BRCA1/2 mutation carriers is not clinically different from noncarriers, although an increased cellular sensitivity to radiation has been documented in lymphocytes and fibroblasts heterozygous for a BRCA1/2 mutation [Foray et al., 1999; Pierce et al., 2000; Savelyeva et al., 2001; Buchholz et al., 2002]. Since BRCA1/2-deficient cells repair DNA by error-prone mechanisms such as nonhomologous end-joining, there is an opportunity to explore therapeutic measures using inhibitors of DNA end-joining [Venkitaraman, 2003]. Breast cancers in mutation carriers (especially BRCA2) may be more sensitive to DNA cross-linking drugs such as mitomycin C. Better understanding of tumor protein expression provides the opportunity to target drug therapy. Herceptin is a monoclonal antibody, directed against the HER-2 receptor, a tyrosine kinase member of the epidermal growth factor receptor family of tyrosine kinases. HER-2 is overexpressed in 20–30% of high-grade invasive breast cancers. The evidence for characteristic HER-2 expression in BRCA1 and BRCA2-associated tumors is conflicting. Lakhani et al.  showed that expression in BRCA1associated tumors is significantly lower than in controls (3% vs. 15%). HER-2 expression in BRCA2 associated tumors was also 3% [Johannsson et al., 1997]. However, other studies have not confirmed this finding [Robson et al., 1998; Armes et al., 1999]. 60 AMERICAN JOURNAL OF MEDICAL GENETICS (SEMIN. MED. GENET.) Preventative Measures Tamoxifen and newer anti-estrogens, e.g., raloxifene, are being evaluated for prevention of breast cancer in women at increased risk. Initial results with tamoxifen were disappointing; it did halve the risk of breast cancer, but also increased the risk of adverse cardiovascular events and endometrial cancer [Narod et al., 2000; Cuzick et al., 2003], and the overall mortality was not reduced in the tamoxifen arm. Further studies are proceeding to address this, and to evaluate newer prophylactic drugs, such as the aromatase inhibitors, which reduce estrogen levels, e.g., anastrozole. There is good evidence that oophorectomy halves the risk of breast cancer, both in the general population and in BRCA1/2 mutation carriers. There is good evidence that oophorectomy halves the risk of breast cancer, both in the general population and in BRCA1/2 mutation carriers [Kauff et al., 2002; Rebbeck, 2002; Meijers-Heijboer et al., 2003], and is a prophylactic option. Prophylactic mastectomy reduces the risk of breast cancer by over 90% [Eisen and Weber, 2001; Narod, 2001; Offit et al., 2001; Rebbeck et al., 2002; Meijers-Heijboer et al., 2003; Taucher et al., 2003]; however, there is likely to be variable amounts of residual breast tissue left in situ. There are also psychological issues to be addressed regarding surgery [Sakorafas, 2003], and uptake of prophylactic mastectomy varies with cultural and religious background [Evans et al., 1999]. Management of Mutation Carriers The five-year and 10-year risk of contralateral breast cancer after a first primary tumor, in BRCA1 and BRCA2 mutation carriers, is 16.9% and 29.9%, respectively; oophorectomy reduces these risks (Hazard Ratio (HR) 0.44) [Narod et al., 2000]. After lumpectomy, the risk of ipsilateral recurrence must also be considered. BRCA2 mutation carriers have a slightly lower risk (HR 0.73), and tamoxifen reduces the recurrence risk (HR 0.59). Prophylactic contralateral mastectomy at surgery for a first primary breast cancer should therefore be considered. In a significant proportion of prophylactic mastectomies in BRCA1/2 carriers reported, early malignant change has been found in the breast specimen [Scott et al., 2003]. Breast cancer prognosis in BRCA1/ 2 mutation carriers appears to be worse than in sporadic cases, although there is conflicting evidence [Foulkes et al., 2000; Lakhani et al., 2000; StoppaLyonnet et al., 2000; Moller et al., 2002; Goffin et al., 2003]. SERVICE DELIVERY, EDUCATION, AND ETHICAL ASPECTS Service delivery involves the recognition of familial breast cancer families at the primary care level, and triage of referrals into low, moderate, or high risk categories, possibly by trained nurses and counselors in family history clinics. High risk families should be referred to genetics clinics. ARTICLE program. Audit of screening outcomes is essential, especially for those at moderate risk, who will be more numerous and diffusely sited than those at high risk. There is a need to provide education about cancer genetics to nongenetics health professionals, to enhance their participation in service delivery, since many express uncertainty about issues surrounding genetic management. The establishment of clear national guidelines is needed [Freedman et al., 2003]. Experience with genetic testing for breast cancer susceptibility over the last decade has allowed ethical principles to be formulated, including the concepts of genetic solidarity and altruism, and respect for persons. Most testing centers will now have proper consenting procedures in place, with counseling and full information. Insurance and employment discrimination is less of a problem than previously, with better education of health and insurance professionals. Government policies around the world are slowly changing to avoid discrimination. The UK (where health service is generally free, and not insurer-based, as in the US) has introduced a moratorium on genetic testing and insurance that allows up to £500,000 worth of insurance coverage to be obtained for purpose of mortgage (house insurance coverage) and £300,000 in cases of health insurance. This applies to approved tests, so far only testing for Huntington disease, although BRCA1 and BRCA2 testing is under consideration by the genetics and insurance committee (GAIC) [Morrison, 2001]. CONCLUSIONS Service delivery involves the recognition of familial breast cancer families at the primary care level, and triage of referrals into low, moderate, or high risk categories, possibly by trained nurses and counselors in family history clinics. High risk families should be referred to genetics clinics. Low risk individuals can be reassured and released from follow-up, and those at moderate risk may be enrolled into an agreed screening The rapid development of proteomic and cDNA microarray techniques has opened up a new dimension of diagnostic potential. CGH, proteomic, and gene expression studies on breast and other cancers in affected women, taken in the context of histopathological data, will help identify their genetic background, and will in turn help identify lower-penetrance genes that cause inherited susceptibility. Such techniques may also be performed on fine-needle ARTICLE aspiration biopsy and needle biopsy specimens of breast tumors [Symmans et al., 2003]. More efficient, cheaper, and faster mutation detection techniques will enlarge the proportion of families for which genetic tests will be available, and speed up the process. Better methods of determining the pathogenicity of novel variants will be vital, particularly if screening for variants in a number of candidate genes is to be performed in the future as a ‘‘risk estimation’’ package [Comings et al., 2003]. However, if consideration is to be given to the development of such a ‘‘multigene test’’ for breast cancer susceptibility, there are many very serious issues that would need to be considered prior to its implementation, including counseling, pre- and post-test system administration, and avoidance of testing of nonconsenting individuals. There seems to be little point in offering such tests unless effective prophylactic measures can be offered to individuals at increased risk. Undue anxiety may otherwise be induced. Careful audit of management is also clearly needed. Insurance and employment issues need to be carefully evaluated and funding needs to be in place for testing, counseling, and for any resultant surveillance programs, with appropriate audit. Over-the-counter genetic tests may be developed in the future, similar to pregnancy or cholesterol tests, and in the UK, recent guidelines have been issued for such ‘‘high utility’’ tests, stipulating that a qualified professional must be involved in consenting and giving results to patients. Tests for highly penetrant genes should not be sold over the counter [Human Genetics Commission, 2004] (www.hgc.gov.uk). Clearly, these are extremely important issues and it is essential that the accuracy of risk interpretation from the test results is assessed before test implementation, with continued long-term evaluation. ACKNOWLEDGMENTS We thank Teresa Mielniczek and Adrienne Knight for their secretarial support. AMERICAN JOURNAL OF MEDICAL GENETICS (SEMIN. MED. GENET.) 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