PALB2 mutations in European familial pancreatic cancer families

Slater EP, Langer P, Niemczyk E, Strauch K, Butler J, Habbe N, Neoptolemos JP, Greenhalf W, Bartsch DK. PALB2 mutations in European pancreatic cancer families. Recently, PALB2 was reported to be a new pancreatic cancer susceptibility gene as determined by exomic sequencing, as truncating PALB2 mutations were identified in 3 of 96 American patients with familial pancreatic cancer (FPC). Representing the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC) and the German National Case Collection for Familial Pancreatic Cancer (FaPaCa), we evaluated whether truncating mutations could also be detected in European FPC families. We have directly sequenced the 13 exons of the PALB2 gene in affected index patients of 81 FPC families. An index patient was defined as the first medically identified patient, stimulating investigation of other members of the family to discover a possible genetic factor. None of these patients carried a BRCA2 mutation. We identified three (3.7%) truncating PALB2 mutations, each producing different stop codons: R414X, 508‐9delAG and 3116delA. Interestingly, each of these three families also had a history of breast cancer. Therefore, PALB2 mutations might be causative for FPC in a small subset of European families, especially in those with an additional occurrence of breast cancer.     

CDKN2A is the main susceptibility gene in Italian pancreatic cancer families

Background Most familial pancreatic cancer (FPC) remains unexplained. The identification of individuals with a high genetic risk of developing pancreatic adenocarcinoma (PC) is important to elucidate its biological basis and is critical to better define emerging strategies for the detection of early pancreatic neoplasms. Patients and methods A series of 225 consecutively enrolled patients with PC were tested for CDKN2A mutations. After personal and family cancer histories of all the patients had been reviewed, a subset of the patients were classified as FPC and were also tested for mutations in PALLD, PALB2, BRCA1 and BRCA2 as FPC candidate genes. Results The CDKN2A mutation rate in the 225 PC cases was 5.7%. The CDKN2A founder mutations, p.E27X and p.G101W, were predominant, but the mutation spectrum also included p.L65P, p.G67R and two novel, potentially pathogenic variants, promoter variant c.-201ACTC>CTTT and p.R144C. None of the patients with FPC harboured germline mutations in PALLD, PALB2 or BRCA2. One family was positive for the BRCA1 UV variant p.P727L. Strikingly, five of 16 patients with FPC (31%) carried CDKN2A mutations. Conclusion These findings suggest that a sizeable subset of Italian FPC families may carry CDKN2A mutations. This result may be of value for identifying the best candidates for future PC screening trials in Italy.     

Prevalence of germ-line mutations in cancer genes among pancreatic cancer patients with a positive family history

PurposePanel-based genetic testing has identified increasing numbers of patients with pancreatic ductal adenocarcinoma (PDAC) who carry germ-line mutations. However, small sample sizes or number of genes evaluated limit prevalence estimates of these mutations. We estimated prevalence of mutations in PDAC patients with positive family history.MethodsWe sequenced 25 cancer susceptibility genes in lymphocyte DNA from 302 PDAC patients in the Mayo Clinic Biospecimen Resource for Pancreatic Research Registry. Kindreds containing at least two first-degree relatives with PDAC met criteria for familial pancreatic cancer (FPC), while the remaining were familial, but not FPC.ResultsThirty-six patients (12%) carried at least one deleterious mutation in one of 11 genes. Of FPC patients, 25/185 (14%) were carriers, while 11/117 (9%) non-FPC patients with family history were carriers. Deleterious mutations (n) identified in PDAC patients were BRCA2 (11), ATM (8), CDKN2A (4), CHEK2 (4), MUTYH/MYH (3 heterozygotes, not biallelic), BRCA1 (2), and 1 each in BARD1, MSH2, NBN, PALB2, and PMS2. Novel mutations were found in ATM, BARD1, and PMS2.ConclusionMultiple susceptibility gene testing in PDAC patients with family history of pancreatic cancer is warranted regardless of FPC status and will inform genetic risk counseling for families.     

Germline RAD51C mutations in ovarian cancer susceptibility

Several genes might explain BRCA1/2 negative breast and ovarian family cases. Deleterious mutations in few genes involved in the Fanconi complex are responsible for Fanconi anemia at the homozygous state and breast cancer (BC) susceptibility at the heterozygous state (BRCA2, PALB2, BRIP1). RAD51C plays an important role in the double‐strand break repair pathway and a biallelic missense mutation in the RAD51C gene was found in a Fanconi anemia‐like disorder. Subsequently, six monoallelic pathogenic mutations were identified after screening 480 BRCA1/2 negative breast and ovarian cancer (BC/OC) pedigrees. Several reports were unsuccessful to replicate these results. To investigate whether germline mutations in RAD51C are associated with an increased risk of developing BC/OC, we screened, by Sanger sequencing of the coding sequence, 117 index cases of breast and ovarian families from French or European origin, and negative for BRCA1/2 mutations. In our study, we found 3 pathogenic mutations among 117 families screened which corresponds to a 2.6% frequency. Our results confirm that RAD51C is a susceptibility gene for ovarian and BC and that this gene should be screened for mutations in families with multiple BC/OC.     

Clinical and genetic analysis of 18 pancreatic carcinoma/melanoma‐prone families

Bartsch DK, Langer P, Habbe N, Matthäi E, Chaloupka B, Sina M, Hahn SA, Slater EP. Clinical and genetic analysis of 18 pancreatic carcinoma/melanoma‐prone families. Families with both melanoma and pancreatic cancer are extremely rare and some are affected with the autosomal dominant inherited familial atypical multiple mole melanoma‐pancreatic cancer (FAMMM‐PC) syndrome. The phenotypic and genotypic expressions of such pancreatic cancer–melanoma prone families are not well defined. The National Case Collection of Familial Pancreatic Cancer of the Deutsche Krebshilfe includes 110 pancreatic cancer families, 18 of which (16%) show an association of pancreatic cancer and melanoma. These 18 families were analysed regarding their phenotype and the prevalence of germline mutations in the candidate genes CDKN2A, BRCA2, CHEK2, NOD2, ARL11 and Palladin (PALLD). There were two types of families: five families with the FAMMM‐PC phenotype and 13 PC/melanoma families without the multiple mole phenotypes (PCMS). The prevalences of PC and melanoma in the two types of families were similar. The prevalence of other tumour types, especially breast carcinoma, was higher (11%) in PCMS‐ than in FAMMM‐PC families (2.4%, p = 0.02). CDKN2A mutations were identified in 2 of 18 (11%) PCMS families. A cosegregating BRCA2 mutation was detected in one PCMS family without breast cancer. None of the reported germline mutations in the NOD2, Palladin, ARL11 or CHEK2 genes were detected in either type of family. In conclusion, families with an accumulation of PC and melanoma show a large variety of phenotypic expression, which is not always consistent with the FAMMM‐PC phenotype. More PC/melanoma‐prone families need to be analysed to clarify whether such families represent variations of the FAMMM‐PC syndrome or two distinct hereditary cancer syndromes.     

Familial pancreatic cancer: genetic advances

Beset by poor prognosis, pancreatic ductal adenocarcinoma is classified as familial or sporadic. This review elaborates on the known genetic syndromes that underlie familial pancreatic cancer, where there are opportunities for genetic counseling and testing as well as clinical monitoring of at-risk patients. Such subsets of familial pancreatic cancer involve germline cationic trypsinogen or PRSS1 mutations (hereditary pancreatitis), BRCA2 mutations (usually in association with hereditary breast–ovarian cancer syndrome), CDKN2 mutations (familial atypical mole and multiple melanoma), or DNA repair gene mutations (e.g., ATM and PALB2, apart from those in BRCA2). However, the vast majority of familial pancreatic cancer cases have yet to have their genetic underpinnings elucidated, waiting in part for the results of deep sequencing efforts.     

BRCA1 mutations in Algerian breast cancer patients: high frequency in young, sporadic cases

Breast cancer rates and median age of onset differ between Western Europe and North Africa. In Western populations, 5 to 10 % of breast cancer cases can be attributed to major genetic factors such as BRCA1 and BRCA2, while this attribution is not yet well defined among Africans. To help determine the contribution of BRCA1 mutations to breast cancer in a North African population, we analysed genomic DNA from breast cancer cases ascertained in Algiers. Both familial cases (at least three breast cancers in the same familial branch, or two with one bilateral or diagnosed before age 40) and sporadic cases less than 38 years of age were studied. Complete sequencing plus quantitative analysis of the BRCA1 gene was performed. 9.8 % (5/51) of early-onset sporadic and 36.4 % (4/11) of familial cases were found to be associated with BRCA1 mutations. This is in contrast 10.3 % of French HBOC families exhibiting a BRCA1 mutation. One mutation, c.798_799delTT, was observed in two Algerian families and in two families from Tunisia, suggesting a North African founder allele. Algerian non-BRCA1 tumors were of significantly higher grade than French non-BRCA tumors, and the age at diagnosis for Algerian familial cases was much younger than that for French non-BRCA familial cases. In conclusion, we observed a much higher frequency of BRCA1 mutations among young breast cancer patients than observed in Europe, suggesting biological differences and that the inclusion criterea for analysis in Western Europe may not be applicable for the Northern African population.     

Germline mutations in the PALB2 gene are population specific and occur with low frequencies in familial breast cancer

The Partner and Localizer of BRCA2 (PALB2) protein has been linked to Fanconi anemia and breast cancer predisposition. Here we present data of a comprehensive mutation screening of the PALB2 gene in 818 familial cases of breast cancer from Germany. By analyzing the entire coding region of PALB2, we found seven truncating mutations (six of them novel) in families tested negative for BRCA1/2-mutations. In addition, two novel potentially disease causing missense mutations were found. Remarkably, only one mutation reported previously in other populations, was also identified in the German population. No PALB2 mutation carriers were identified in 450 unaffected controls. Thus, our observations indicate a low prevalence of deleterious PALB2 mutations and a specific mutation profile within the German population. As PALB2-deficient tumors were shown to be sensitive to Poly(ADP-ribose) Polymerase (PARP) inhibitors, our study has implications for newly developed, favorable treatment options in familial breast cancer.     

CHEK2基因c.1100delC与中国人遗传性乳腺癌易感性的关联研究

目的研究上海地区非BRCA1／2基因突变的遗传倾向乳腺癌中CHEK2基因c．1100delC突变的携带情况及可能的作用。方法研究对象来自114例遗传倾向性乳腺癌，包括家族性乳腺癌76例，其中8例发病年龄低于40岁；38例单纯早发性乳腺癌（发病年龄〈40岁）。对照组为121名无乳腺癌的健康女性，静脉血中提取基因组DNA，对CHEK2基因的第10～14外显子进行长片段PCR扩增，PCR产物再进行含突变的第10外显子的扩增。突变分析全部由DNA直接测序进行鉴定。结果研究人群和对照人群中都没有发现c．1100delC的突变；在3例（3／114，2．6％）家族性乳腺癌中发现邻近c．1100delC的新的错义突变位点1111C〉T（p-His371 Tyr），对照组中则无此突变发现。结论CHEK2基因c．1100delC突变可能是中国人群罕见的突变位点，在中国人乳腺癌遗传易感性中的作用非常有限；1111C〉T可能与中国上海地区遗传倾向乳腺癌低度外显的易感性有关，需要进行进一步研究确认。     

BRCA1, BRCA2, PALB2, and CDKN2A mutations in familial pancreatic cancer: a PACGENE study

PurposeFamilial pancreatic cancer kindreds contain at least two affected first-degree relatives. Comprehensive data are needed to assist clinical risk assessment and genetic testing.MethodsGerm-line DNA samples from 727 unrelated probands with positive family history (521 met criteria for familial pancreatic cancer) were tested in compliance with the Clinical Laboratory Improvement Amendments for mutations in BRCA1 and BRCA2 (including analysis of deletions and rearrangements), PALB2, and CDKN2A. We compared prevalence of deleterious mutations between familial pancreatic cancer probands and nonfamilial pancreatic cancer probands (kindreds containing at least two affected biological relatives, but not first-degree relatives). We also examined the impact of family history on breast and ovarian cancers and melanoma.ResultsPrevalence of deleterious mutations (excluding variants of unknown significance) among familial pancreatic cancer probands was: BRCA1, 1.2%; BRCA2, 3.7%; PALB2, 0.6%; and CDKN2A, 2.5%. Four novel deleterious mutations were detected. Familial pancreatic cancer probands carry more mutations in the four genes (8.0%) than nonfamilial pancreatic cancer probands (3.5%) (odds ratio: 2.40; 95% confidence interval: 1.06−5.44; P = 0.03). The probability of testing positive for deleterious mutations in any of the four genes ranges up to 10.4%, depending on family history of cancers. BRCA2 and CDKN2A account for the majority of mutations in familial pancreatic cancer.ConclusionGenetic testing of multiple relevant genes in probands with a positive family history is warranted, particularly for familial pancreatic cancer.Genet Med 17 7, 569–577.     

Detection of novel germline mutations in six breast cancer predisposition genes by targeted next‐generation sequencing

In this study, a customized amplicon‐based target sequencing panel was designed to enrich the whole exon regions of six genes associated with the risk of breast cancer. Targeted next‐generation sequencing (NGS) was performed for 146 breast cancer patients (BC), 71 healthy women with a family history of breast cancer (high risk), and 55 healthy women without a family history of cancer (control). Sixteen possible disease‐causing mutations on four genes were identified in 20 samples. The percentages of possible disease‐causing mutation carriers in the BC group (8.9%) and in the high‐risk group (8.5%) were higher than that in the control group (1.8%). The BRCA1 possible disease‐causing mutation group had a higher prevalence in family history and triple‐negative breast cancer, while the BRCA2 possible disease‐causing mutation group was younger and more likely to develop axillary lymph node metastasis (P < 0.05). Among the 146 patients, 47 with a family history of breast cancer were also sequenced with another 14 moderate‐risk genes. Three additional possible disease‐causing mutations were found on PALB2, CHEK2, and PMS2 genes, respectively. The results demonstrate that the six‐gene targeted NGS panel may provide an approach to assess the genetic risk of breast cancer and predict the clinical prognosis of breast cancer patients.     

Low prevalence of SLX4 loss-of-function mutations in non-BRCA1/2 breast and/or ovarian cancer families

Fanconi anemia is a genetically heterogeneous autosomal recessive disorder characterized by development abnormalities, bone marrow failure, and childhood cancers. Compelling evidence indicates a common genetic basis for FA and breast/ovarian cancer susceptibility. Recently, biallelic germ-line mutations in SLX4 have been demonstrated to cause a previously unknown FA subtype (FA-P). We address the role of SLX4/FANCP in breast/ovarian cancer susceptibility by conducting a comprehensive mutation scanning in 486 index cases from non-BRCA1/BRCA2 multiple-case breast and/or ovarian cancer families (non-BRCA1/2 families) from Spain. We detected one unequivocal loss-of-function mutation (p.Glu1517X). In addition, one missense change (p.Arg372Trp) predicted to be pathogenic by in silico analysis co-segregates with disease in one family. Overall, the study indicates that SLX4 mutation screening will have a very low impact (if any) in the genetic counseling of non-BRCA1/2 families.     

Genetic susceptibility to non-polyposis colorectal cancer

Familial colorectal cancer (CRC) is a major public health problem by virtue of its relatively high frequency. Some 15-20% of all CRCs are familial. Among these, familial adenomatous polyposis (FAP), caused by germline mutations in the APC gene, accounts for less than 1%. Hereditary non-polyposis colorectal cancer (HNPCC), also called Lynch syndrome, accounts for approximately 5-8% of all CRC patients. Among these, some 3% are mutation positive, that is, caused by germline mutations in the DNA mismatch repair genes that have so far been implicated (MLH1, MSH2, MSH6, PMS1, and PMS2). Most of the remaining patients belonging to HNPCC or HNPCC-like families are still molecularly unexplained. Among the remaining familial CRCs, a large proportion is probably caused by gene mutations and polymorphisms of low penetrance, of which the I1307K polymorphism in the APC gene is a prime example.Molecular genetic findings have enabled hereditary CRC to be divided into two groups: (1) tumours that show microsatellite instability (MSI), occur more frequently in the right colon, have diploid DNA, harbour characteristic mutations such as transforming growth factor beta type II receptor and BAX, and behave indolently, of which HNPCC is an example; and (2) tumours with chromosomal instability (CIN), which tend to be left sided, show aneuploid DNA, harbour characteristic mutations such as K-ras, APC, and p53, and behave aggressively, of which FAP is an example. This review focuses most heavily on the clinical features, pathology, molecular genetics, surveillance, and management including prophylactic surgery in HNPCC. Because of the difficulty in diagnosing HNPCC, a detailed differential diagnosis of the several hereditary CRC variants is provided. The extant genetic and phenotypic heterogeneity in CRC leads to the conclusion that it is no longer appropriate to discuss the genetics of CRC without defining the specific hereditary CRC syndrome of concern. Therefore, it is important to ascertain cancer of all anatomical sites, as well as non-cancer phenotypic stigmata (such as the perioral and mucosal pigmentations in Peutz-Jeghers syndrome), when taking a family cancer history.     

BRCA1 and pancreatic cancer: pedigree findings and their causal relationships

Anecdotal reports and series studies indicate that 5-10% of pancreatic cancer (PC) cases are familial. In addition, PC is associated with a variety of hereditary cancer syndromes. PC appears to be an integral cancer in the hereditary breast-ovarian cancer (HBOC) syndrome, with most notice given to the role of BRCA2. Our purpose is to call attention to BRCA1, which also predisposes to PC. Using data from our familial breast cancer registry, we identified 19 BRCA1/2 families that contain PC affecteds in the pedigrees, 15 with BRCA1 mutations and 4 with BRCA2 mutations. The association between BRCA2 and pancreatic cancer is well established; however, a definite link with pancreatic cancer in families carrying a BRCA1 mutation has been far less studied. Thus, the focus of this report is on 9 of the 15 BRCA1 families, in which PC affecteds were either confirmed carriers of the BRCA1 mutation or were inferred as probable obligate BRCA1 mutation carriers. The numbers are small, but nevertheless illustrate the finding of others of an apparent association between PC and BRCA1-mutation-bearing families. Given the dismal prognosis of PC, with the only current hope for survival being through surgical extirpation of the pancreas prior to metastasis, it is prudent that we realize the potential predisposition toward PC via BRCA1, in the hope of early diagnosis and prevention.     

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.     

Screening E-cadherin in gastric cancer families reveals germline mutations only in hereditary diffuse gastric cancer kindred

The International Gastric Cancer Linkage Consortium (IGCLC) predicted that up to 25% of families fulfilling the criteria for hereditary diffuse gastric cancer (HDGC) would harbor CDH1 germline mutations. This was based on observations from the low number of diffuse gastric cancer families described at the time, and its validation would require analysis of larger numbers. Here we report the results of germline CDH1 mutation screening in 39 kindred with familial aggregation of gastric cancer, a subset of which fulfills the criteria defined by the IGCLC for HDGC. CDH1 germline mutations were detected in four of 11 (36.4%) HDGC families. No mutations were identified in 63.6% of HDGC families or in kindred with familial aggregation of gastric cancer not fulfilling criteria for HDGC. These results add support to the evidence that only HDGC families harbor germline mutations in CDH1 and that genes other than CDH1 remain to be identified.     

Hereditary breast and ovarian cancer: review and future perspectives

Breast cancer (BC) is the most frequent carcinoma in women. The cumulative risk for the disease is 10% up to the age of 80 years. A familial history of BC and ovarian cancer (OC) is a significant risk factor. Some 5–10% of all cases of BC and 25–40% of cases in patients under the age of 35 years have a hereditary origin. BRCA1/BRCA2 mutations are responsible for 3–8% of all cases of BC and 30–40% of familial cases. Ten percent of patients with OC have a genetic predisposition. About 80% of families with a history of OC have BRCA1 mutations, while 15% have BRCA2 mutations. Women at risk can receive counseling from interdisciplinary cancer genetics clinics, while those at high risk can receive genetic testing. Risk calculation programs can define the risks and assist in decision making for genetic testing and clinical options. Clinical options require information on the risks of the disease and its mutation status. Chemoprevention is currently a controversial topic, while the use of oral contraceptives can be regarded as reducing the risk for OC. Prophylactic mastectomy and bilateral ovariectomy are the only options that lead to a demonstrable reduction in risk, but they do, of course, affect the patients physical integrity. It is not currently known whether intensified early cancer detection is individually beneficial, but this is currently the option that is the least invasive and least burdensome to the patient. Although hereditary BC has different pathological characteristics and the BRCA mutation is an independent negative prognostic factor, there are currently no special treatment guidelines. Without adjuvant hormone therapy or chemotherapy, the overall survival in BRCA mutation carriers is reduced. Chemotherapy regimens involving platinum are particularly beneficial in the treatment of hereditary BC.     

Analysis of RAD51C germline mutations in high-risk breast and ovarian cancer families and ovarian cancer patients

There is strong evidence that overtly inactivating mutations in RAD51C predispose to hereditary breast and ovarian cancer but the prevalence of such mutations, and whether they are associated with a particular clinical phenotype, remains unclear. Resolving these questions has important implications for the implementation of RAD51C into routine clinical genetic testing. Consequently, we have performed a large RAD51C mutation screen of hereditary breast and ovarian cancer families, and the first study of unselected patients diagnosed with ovarian cancer. Our data confirm a consistent but low frequency (2/335 families) of inactivating RAD51C mutations among families with a history of both breast and ovarian cancer and an absence of mutations among breast cancer only families (0/1,053 families). Our data also provide support for the designation of the missense variant p.Gly264Ser as a moderate penetrance allele.