Germline BRCA1 and HMLH1 mutations in a family with male and female breast carcinoma

A Japanese case of ovarian mucinous adenocarcinoma with germline double variants of MSH2 and BRCA2

Germline double heterozygosity (GDH) is rarely reported in cases of inherited cancer syndromes, and GDH of a mismatch repair gene and BRCA has never been reported in Japan. Nonetheless, the current report demonstrates a case of ovarian mucinous adenocarcinoma with initiated Lynch syndrome (LS)-related surveillance because of a known germline MSH2 variant. Six and a half years after oophorectomy, multiple tumors developed in the patient's lungs, bones, and lymph nodes, and histology results confirmed mucinous adenocarcinoma. Systemic chemotherapy including an anti-PD-L1 antibody was effective for >1 year, but brain metastases developed. Pathology of the brain tumors showed mucinous adenocarcinoma without expression of MSH2 and MSH6, while multi-gene panel testing demonstrated not only high microsatellite instability and a high tumor mutation burden, but also germline BRCA2 variants. Further, germline testing in relatives confirmed both variants were from the paternal line, from which many LS-related cancers develop, but not BRCA-related cancer.

Double heterozygotes of BRCA1/BRCA2 and mismatch repair gene pathogenic variants: case series and clinical implications

BACKGROUND

Hereditary breast and ovarian cancer syndrome (HBOC) and Lynch syndrome (LS), the most common inherited cancer syndromes, are attributed to a single heterozygous pathogenic variant (PV) in BRCA1/2 or in a DNA MMR gene, respectively. Little is known about the phenotype in double heterozygotes who carry PVs in both genes.

METHODS

Carriers of double-PVs in any DNA MMR gene and BRCA1/2 attending one of three tertiary oncogenetic clinics between 1/2005 and 1/2020 were identified by database search, and their relevant data were retrieved and analyzed.

RESULTS

Eleven double carriers from four seemingly unrelated Ashkenazi Jewish families were evaluated. All carried an Ashkenazi Jewish founder BRCA PV, BRCA2 c.5946delT/c.6174delT (n = 10) or BRCA1 c.185delAG (n = 1). Four carried the MSH2 c.1906G > C founder PV, and 3, the MSH6 c.3984_3987dupGTCA founder PV; 3 patients had the MSH6 c.3956_3957dup PV. Eight double carriers (73%) had cancer: breast cancer (5 cases, 2 bilateral), melanoma (2 cases), urothelial cancer (2 cases), and colon, endometrial, prostate, cutaneous squamous cell cancer, glioblastoma, gastric stromal tumor, and lymphoma (1 case each). Six carriers had 1-2 tumors, one had 3 tumors, and one had 5 primary tumors. Age at diagnosis of the first tumor was 36-76 years. All carriers met NCCN BRCA1/2 testing criteria, and 3 met the revised Bethesda guidelines.

CONCLUSIONS

This case series, supported by the literature, suggests that the phenotype of double MSH2/6 and BRCA1/2 carriers is not associated with early disease onset or a more severe phenotype. The findings have implications for improved genetic testing guidelines and treatment strategies.

The implications of BRCA loss of heterozygosity (LOH) and deficient mismatch repair gene (dMMR) expression in the breast cancer of a patient with both inherited breast and ovarian cancer syndrome (BRCA2) and Lynch syndrome (MLH1)

BACKGROUND

BRCA germline pathogenic variants represent the most common inherited mechanism predisposing individuals to breast cancer, while germline pathogenic variants in one of the mismatch repair (MMR) genes represent the most common colon cancer-predisposing inherited syndrome, known as the Lynch syndrome (LS). Individuals who harbor pathogenic germline variants for both syndromes are extremely rare. Germline testing is now done routinely for patients with breast cancer and MMR testing is recommended for nearly all patients diagnosed with colon or rectal cancer (Benson et al in NCCN clinical practice guidelines in oncology (NCCN guidelines) colon cancer (Version 4.2019-November 8, 2019). www.NCCN.org, Gradishar et al in NCCN clinical practice guidelines in oncology (NCCN guidelines) breast cancer (Version 3.2019-September 6, 2019).www.NCCN.org). We report a patient with germline mutations in both BRCA2 and the MMR gene MLH1 who developed breast cancer. The breast cancer showed loss of heterozygosity (LOH) in BRCA2 (the molecular hallmark of cancers related to inheritance of a BRCA alteration) and was also deficient in mismatch repair gene protein expression (dMMR), the hallmark of LS-related cancers. We discuss the possible mechanisms of transformation that would explain the finding that the tumor showed both BRCA2 LOH and was dMMR, each of which would generally be considered a gatekeeper event for transformation of normal cells to malignancy.

RESULTS

This report describes a patient with molecularly diagnosed breast and ovarian cancer syndrome (BRCA2) and LS. Next generation sequencing (NGS) and immunohistochemical (IHC) testing demonstrated her breast cancer to show BRCA2 LOH and to be dMMR.

CONCLUSION

The patient presented represents the first reported case where both next generation sequencing (NGS) for BRCA LOH and MMR IHC testing of her breast cancer were performed and underscores the importance of using NGS including the reported mutational allelic frequency (MAF) and IHC use to predict the likely responsiveness to the recently approved PARP inhibitors and checkpoint inhibitor therapies (Robson et al in N Engl J Med 377:523-533, 2017, Lemery et al in 377(15):1409-1412, https://doi.org/10.1056/NEJMp1709968, 2017), key because the gatekeeper transforming event for tumors related to inherited cancer syndromes is loss of normal tumor suppressor gene (TSG) protein expression.

Delineating a new feature of constitutional mismatch repair deficiency (CMMRD) syndrome: breast cancer

Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare autosomal recessive hereditary cancer condition, characterized by an exceptionally high risk of cancer, a propensity for childhood malignancies, and cutaneous features reminiscent of neurofibromatosis type 1 (NF1). We report on two sisters originally suspected of having CMMRD syndrome due to their history of colonic polyps and NF1 associated skin findings, both were subsequently found to have biallelic MSH6 mutations. After years of CMMRD syndrome follow-up, the proband was diagnosed with breast cancer at age 29, while her sister was diagnosed with a glioblastoma at age 27. Immunohistochemistry analysis on the breast tumor tissue revealed weak MSH6 protein staining. Exome sequencing revealed a hypermutated breast tumor and an ultra-hypermutated brain tumor. Multi-gene panel testing was also performed and revealed no additional mutations which might explain the proband's early onset breast cancer. This is the first documented case of breast cancer in an individual with CMMRD syndrome. We summarize the evidence supporting the possible association between breast cancer and biallelic MMR mutations. Healthcare providers should be aware of this possible association and follow-up appropriately for suspicious breast findings. In addition, this case highlights the need for frequent central nervous system screenings due to rapid progression of brain tumors.

The importance of proper bioinformatics analysis and clinical interpretation of tumor genomic profiling: a case study of undifferentiated sarcoma and a constitutional pathogenic BRCA2 mutation and an MLH1 variant of uncertain significance

Next-generation sequencing (NGS) technology is increasingly utilized to identify therapeutic targets for patients with malignancy. This technology also has the capability to reveal the presence of constitutional genetic alterations, which may have significant implications for patients and their family members. Here we present the case of a 23 year old Caucasian patient with recurrent undifferentiated sarcoma who had NGS-based tumor analysis using an assay which simultaneously analyzed the entire coding sequence of 236 cancer-related genes (3769 exons) plus 47 introns from 19 genes often rearranged or altered in cancer. Pathogenic alterations were reported in tumor as the predicted protein alterations, BRCA2 “R645fs*15″ and MLH1 “E694*”. Because constitutional BRCA2 and MLH1 gene mutations are associated with Hereditary Breast Ovarian Cancer Syndrome (HBOCS) and Lynch syndrome respectively, sequence analysis of DNA isolated from peripheral blood was performed. The presence of the alterations, BRCA2 c.1929delG and MLH1 c.2080G>T, corresponding to the previously reported predicted protein alterations, were confirmed by Sanger sequencing in the constitutional DNA. An additional DNA finding was reported in this analysis, MLH1 c.2081A>C at the neighboring nucleotide. Further evaluation of the family revealed that all alterations were paternally inherited and the two MLH1 substitutions were in cis, more appropriately referred to as MLH1 c.2080_2081delGAinsTC, which is classified as a variant of uncertain significance. This case illustrates important considerations related to appropriate interpretation of NGS tumor results and follow-up of patients with potentially deleterious constitutional alterations.

Identification of a comprehensive spectrum of genetic factors for hereditary breast cancer in a Chinese population by next-generation sequencing

The genetic etiology of hereditary breast cancer has not been fully elucidated. Although germline mutations of high-penetrance genes such as BRCA1/2 are implicated in development of hereditary breast cancers, at least half of all breast cancer families are not linked to these genes. To identify a comprehensive spectrum of genetic factors for hereditary breast cancer in a Chinese population, we performed an analysis of germline mutations in 2,165 coding exons of 152 genes associated with hereditary cancer using next-generation sequencing (NGS) in 99 breast cancer patients from families of cancer patients regardless of cancer types. Forty-two deleterious germline mutations were identified in 21 genes of 34 patients, including 18 (18.2%) BRCA1 or BRCA2 mutations, 3 (3%) TP53 mutations, 5 (5.1%) DNA mismatch repair gene mutations, 1 (1%) CDH1 mutation, 6 (6.1%) Fanconi anemia pathway gene mutations, and 9 (9.1%) mutations in other genes. Of seven patients who carried mutations in more than one gene, 4 were BRCA1/2 mutation carriers, and their average onset age was much younger than patients with only BRCA1/2 mutations. Almost all identified high-penetrance gene mutations in those families fulfill the typical phenotypes of hereditary cancer syndromes listed in the National Comprehensive Cancer Network (NCCN) guidelines, except two TP53 and three mismatch repair gene mutations. Furthermore, functional studies of MSH3 germline mutations confirmed the association between MSH3 mutation and tumorigenesis, and segregation analysis suggested antagonism between BRCA1 and MSH3. We also identified a lot of low-penetrance gene mutations. Although the clinical significance of those newly identified low-penetrance gene mutations has not been fully appreciated yet, these new findings do provide valuable epidemiological information for the future studies. Together, these findings highlight the importance of genetic testing based on NCCN guidelines and a multi-gene analysis using NGS may be a supplement to traditional genetic counseling.

Germline truncating-mutations in BRCA1 and MSH6 in a patient with early onset endometrial cancer

Background

Hereditary Breast and Ovarian Cancer Syndrome (HBOCS) and Hereditary Non-Polyposis Colorectal Cancer Syndrome (HNPCC, Lynch Syndrome) are two tumor predisposition syndromes responsible for the majority of hereditary breast and colorectal cancers. Carriers of both germline mutations in breast cancer genes BRCA1 or BRCA2 and in mismatch repair (MMR) genes MLH1, MSH2, MSH6 or PMS2 are very rare.

Case presentation

We identified germline mutations in BRCA1 and in MSH6 in a patient with increased risk for HBOC diagnosed with endometrial cancer at the age of 46 years.

Conclusions

Although carriers of mutations in both MMR and BRCA genes are rare in Caucasian populations and anamnestical and histopathological findings may guide clinicians to identify these families, both syndromes can only be diagnosed through a complete gene analysis of the respective genes.

Hereditary ovarian carcinoma: heterogeneity, molecular genetics, pathology, and management

Hereditary ovarian cancer accounts for at least 5% of the estimated 22,000 new cases of this disease during 2009. During this same time, over 15,000 will die from malignancy ascribed to ovarian origin. The bulk of these hereditary cases fits the hereditary breast-ovarian cancer syndrome, while virtually all of the remainder will be consonant with the Lynch syndrome, disorders which are autosomal dominantly inherited. Advances in molecular genetics have led to the identification of BRCA1 and BRCA2 gene mutations which predispose to the hereditary breast-ovarian cancer syndrome, and mutations in mismatch repair genes, the most common of which are MSH2 and MLH1, which predispose to Lynch syndrome. These discoveries enable relatively certain diagnosis, limited only by their variable penetrance, so that identification of mutation carriers through a comprehensive cancer family history might be possible. This paper reviews the subject of hereditary ovarian cancer, with particular attention to its molecular genetic basis, its pathology, and its phenotypic/genotypic heterogeneity.

Understanding the development of human bladder cancer by using a whole-organ genomic mapping strategy

The search for the genomic sequences involved in human cancers can be greatly facilitated by maps of genomic imbalances identifying the involved chromosomal regions, particularly those that participate in the development of occult preneoplastic conditions that progress to clinically aggressive invasive cancer. The integration of such regions with human genome sequence variation may provide valuable clues about their overall structure and gene content. By extension, such knowledge may help us understand the underlying genetic components involved in the initiation and progression of these cancers. We describe the development of a genome-wide map of human bladder cancer that tracks its progression from in situ precursor conditions to invasive disease. Testing for allelic losses using a genome-wide panel of 787 microsatellite markers was performed on multiple DNA samples, extracted from the entire mucosal surface of the bladder and corresponding to normal urothelium, in situ preneoplastic lesions, and invasive carcinoma. Using this approach, we matched the clonal allelic losses in distinct chromosomal regions to specific phases of bladder neoplasia and produced a detailed genetic map of bladder cancer development. These analyses revealed three major waves of genetic changes associated with growth advantages of successive clones and reflecting a stepwise conversion of normal urothelial cells into cancer cells. The genetic changes map to six regions at 3q22-q24, 5q22-q31, 9q21-q22, 10q26, 13q14, and 17p13, which may represent critical hits driving the development of bladder cancer. Finally, we performed high-resolution mapping using single nucleotide polymorphism markers within one region on chromosome 13q14, containing the model tumor suppressor gene RB1, and defined a minimal deleted region associated with clonal expansion of in situ neoplasia. These analyses provided new insights on the involvement of several non-coding sequences mapping to the region and identified novel target genes, termed forerunner (FR) genes, involved in early phases of cancer development.

Male breast cancer: is the scenario changing

Background

The overall incidence of male breast cancer is around 1% of all breast cancers and is on the rise. In this review we aim to present various aspects of male breast cancer with particular emphasis on incidence, risk factors, patho-physiology, treatment, prognostic factors, and outcome.

Methods

Information on all aspects of male breast cancer was gathered from available relevant literature on male breast cancer from the MEDLINE database over the past 32 years from 1975 to 2007. Various reported studies were scrutinized for emerging evidence. Incidence data were also obtained from the IARC, Cancer Mondial database.

Conclusion

There is a scenario of rising incidence, particularly in urban US, Canada and UK. Even though more data on risk factors is emerging about this disease, more multi-institutional efforts to pool data with large randomized trials to show treatment and survival benefits are needed to support the existing vast emerging knowledge about the disease.

Estrogen receptor alpha, BRCA1, and FANCF promoter methylation occur in distinct subsets of sporadic breast cancers

Estrogen receptor alpha (ER) and its ligand estrogen play vital roles in the development, progression and treatment of breast cancer. An increasing number of studies have also provided evidence linking disruption of the Fanconi anemia/BRCA cascade to breast cancer. Our objectives were to examine the methylation status and expression profiles of ER, correlate the findings with BRCA1 and FANCF methylation and map the critical CpGs for ER expression. We found that the CpG islands in the 5' region of the ER gene are methylated in 59 of 120 (49.2%) primary breast cancers, including 45 of 59 ER-negative tumors (76.3%, P < 0.00001). In addition, we observed a strong correlation between ER promoter and BRCA1 promoter methylation (odds ratio 3.12, 95% confidence interval 1.10-9.68, P = 0.02). In contrast, FANCF methylation was rare in breast tumors: one of 120 (0.8%). ER methylation was associated with high tumor grade (60.4% methylated vs. 39.6% unmethylated in grade 3 tumors, P = 0.04) and tumor subtype (P = 0.03). Though small in number, all tumors of the medullary subtype were ER methylated. In contrast, the lobular subtype had the least methylation (23.1% methylated vs. 76.9% unmethylated). After treatment of MDA-MB-231 cells with 5-aza-cytidine (5-aza-dC) and trichostatin, which resulted in re-expression of ER mRNA, we localized dramatic demethylation effects to CpG islands in positions +68, +165, +192, +195, +337, +341 and +405 from transcription start site of the ER promoter. These data suggest that unlike FANCF, both ER and BRCA1 are specifically targeted for methylation in sporadic breast cancers, a phenomenon that should be explored for development of novel diagnostic and therapeutic approaches.

BRCA1, BRCA2, TP53, and CDKN2A germline mutations in patients with breast cancer and cutaneous melanoma

PURPOSE

From epidemiological studies it appears that breast cancer (BC) and cutaneous melanoma (CMM) in the same individual occur at a higher frequency than expected by chance. Genetic factors common to both cancers can be suspected. Our goal was to estimate the involvement of "high risk" genes in patients presenting these two neoplasia, selected irrespectively from family history and age at diagnosis.

EXPERIMENTAL DESIGN

Eighty two patients with BC and CMM were screened for BRCA1, BRCA2, TP53, CDKN2A and CDK4 (exon 2) germline mutations.

RESULTS

Deleterious mutations were identified in 6 patients: two carriers of a BRCA1 germline mutation, two carriers of TP53 germline mutations (one of which also harbored a BRCA2 deleterious mutation, the other one a BRCA2 unclassified variant), and two carriers of a CDKN2A germline mutation. In addition, 6 variants of unknown signification were identified in BRCA1 or BRCA2 genes. Regarding family history, 3/13 (23%) patients with a positive family history of BC or CMM were carriers of a germline mutation, whereas only 3/69 (4%) patients without family history were carriers of a germline mutation.

CONCLUSION

Our findings show that few patients with BC and CMM who lacked family histories of these cancers are carriers of deleterious germline mutations in four of the five genes we examined. We describe for the first time, two simultaneous BRCA2 and TP53 mutations, suggesting that analysis in more than one gene could be performed if a patient's personal or familial history does not match a single syndrome.

Assay validation for identification of hereditary nonpolyposis colon cancer-causing mutations in mismatch repair genes MLH1, MSH2, and MSH6

Hereditary nonpolyposis colon cancer (HNPCC, Online Mendelian Inheritance in Man (OMIM) 114500) is an autosomal dominant disorder that is genetically heterogeneous because of underlying mutations in mismatch repair genes, primarily MLH1, MSH2, and MSH6. One challenge to correctly diagnosing HNPCC is that the large size of the causative genes makes identification of mutations both labor intensive and expensive. We evaluated the usefulness of denaturing high performance liquid chromatography (DHPLC) for scanning mismatch repair genes (MLH1, MSH2, and MSH6) for point mutations, small deletions, and insertions. Our assay consisted of 51 sets of primers designed to amplify all exons of these genes. All polymerase chain reaction reactions were amplified simultaneously using the same reaction conditions in a 96-well format. The amplified products were analyzed by DHPLC across a range of optimum temperatures for partial fragment denaturation based on the melting profile of each specific fragment. DNA specimens from 23 previously studied HNPCC patients were analyzed by DHPLC, and all mutations were correctly identified and confirmed by sequence analysis. Here, we present our validation studies of the DHPLC platform for HNPCC mutation analysis and compare its merits with other scanning technologies. This approach provides greater sensitivity and more directed molecular analysis for clinical testing in HNPCC.

Germline truncating mutations in both MSH2 and BRCA2 in a single kindred

There has been interest in the literature in the possible existence of a gene that predisposes to both breast cancer (BC) and colorectal cancer (CRC). We describe the detailed characterisation of one kindred, MON1080, with 10 cases of BC or CRC invasive cancer among 26 first-, second- or third-degree relatives. Linkage analysis suggested that a mutation was present in BRCA2. DNA sequencing from III: 22 (diagnosed with lobular BC) identified a BRCA2 exon 3 542G>T (L105X) mutation. Her sister (III: 25) had BC and endometrial cancer and carries the same mutation. Following immunohistochemical and microsatellite instability studies, mutation analysis by protein truncation test, cDNA sequencing and quantitative real-time PCR revealed a deletion of MSH2 exon 8 in III: 25, confirming her as a double heterozygote for truncating mutations in both BRCA2 and MSH2. The exon 8 deletion was identified as a 14.9 kb deletion occurring between two Alu sequences. The breakpoint lies within a sequence of 45 bp that is identical in both Alu sequences. In this large BC/CRC kindred, MON1080, disease-causing truncating mutations are present in both MSH2 and BRCA2. There appeared to be no increased susceptibility to the development of colorectal tumours in BRCA2 mutation carriers or to the development of breast tumours in MSH2 mutation carriers. Additionally, two double heterozygotes did not appear to have a different phenotype than would be expected from the presence of a mutation in each gene alone.

Familial breast and bowel cancer: does it exist?

There is much debate in the literature about familial predispositions to breast and bowel cancers yet little evidence is forthcoming to suggest that there are susceptibility genes that can account for such kindreds. Within the context of known susceptibility genes the most controversial syndrome is hereditary non-polyposis colorectal cancer (HNPCC). In HNPCC, breast cancers do occur yet their incidence overall is no different to that of the general population yet when studied at the molecular level these tumours often display DNA microsatellite instability suggesting that they do indeed belong to this genetic entity. In this review we examine the relationship between breast and bowel cancer and suggest a possible explanation for the diverse points of view described in the literature.

Analysis for phenotype of HNPCC in China

AIM: The aims of this study were to identify the clinicopathological features of Chinese HNPCC families and to evaluate the value of criteria for suspected HNPCC (sHNPCC) in clinical diagnosis.

METHODS: According to the follow-up records, 54 HNPCC families (including 12 ICG-HNPCC families and 42 sHNPCC families) were screened out from patients with colorectal cancers (CRCs), operated upon in 2^nd Affiliated Hospital of Zhejiang University from 1984 to 2001. Clinical data of probands and tumor spectrum in these families were listed and analyzed.

RESULTS: (1) Mean age, proportion of colonic cancer, poorly differentiated cancer, multiple CRCs and Dukes’ A+B of the probands in ICG-HNPCC and sHNPCC kindred were 39 ys and 47.5 ys, 75% and 62%, 0 and 12.8%, 16.7% and 14.3%, 58.3% and 81%, respectively. Compared with sporadic colorectal cancers, probands from ICG-HNPCC and sHNPCC families were obviously different at age of onset (P = 0.025 and 0.031), tumor location (P = 0.001 and 0.000), differentiation (P = 0.002 and 0.011) and development of multiple tumors (P = 0.014 and 0.002). (2) A total of 178 malignant neoplasms were found in 54 HNPCC families, including 139 colorectal cancers. Besides of colorectal cancer, extracolonic tumors occurred in stomach, endometrium, hepatobiliary system, and so on (8 gastric cancers, 6 endometrial cancers, 6 hepatobiliary system cancers and 19 others) can also be seen in Chinese ICG-HNPCC and sHNPCC families.

CONCLUSION: (1) Chinese HNPCC families have specific clinicopathological features, such as early onset, predilection for the involvement of colon, tendency of multiple CRCs, development of extracolonic tumors and well differentiation. (2) The criteria for suspected HNPCC is useful in clinical diagnosis and management of HNPCC.

Evaluation of the needs of male carriers of mutations in BRCA1 or BRCA2 who have undergone genetic counseling

To date, the concerns of men at risk of inheriting a BRCA1 mutation or a BRCA2 mutation have received little attention. It had been anticipated that few men would be interested in predictive testing when a BRCA mutation was identified in their family. However, these men are often affected emotionally by diagnoses of breast cancer in their relatives and may themselves harbor fears that cancer will develop. Male carriers of BRCA1/2 mutations are at increased risk of development of cancers of several types, including those of the breast and prostate. We conducted an evaluation of the needs and experiences of 59 male carriers of BRCA1/2 mutations followed at either the University of Toronto or Creighton University. We assessed their motivations for seeking genetic counseling and testing, involvement in family discussions of breast and ovarian cancer, risk perception, changes in cancer-screening practices, and overall satisfaction with the genetic-counseling process. The principal motivation for seeking genetic counseling was concern for their daughters. The majority (88%) of men participated in family conversations about breast and ovarian cancer, and 47% participated in conversations about prophylactic surgery. Most men believed that they were at increased risk of development of cancer (prostate, breast, colorectal, and skin cancers). However, fewer than one-half (43%) of the men with no previous diagnosis of cancer stated that their prostate cancer-surveillance practices had changed after they had received genetic test results. More than one-half (55%) had intrusive thoughts about their cancer risk. Although levels of satisfaction were high, practitioners should be aware of (a) potential pressures influencing men to request predictive testing, (b) the difficulties that men encounter in establishing surveillance regimens for breast and prostate cancer, and (c) the general lack of information about men's particular experiences in the medical community.