Multigene Panel Germline Testing of 1333 Czech Patients with Ovarian Cancer.

Ovarian cancer (OC) is the deadliest gynecologic malignancy with a substantial proportion of hereditary cases and a frequent association with breast cancer (BC). Genetic testing facilitates treatment and preventive strategies reducing OC mortality in mutation carriers. However, the prevalence of germline mutations varies among populations and many rarely mutated OC predisposition genes remain to be identified. We aimed to analyze 219 genes in 1333 Czech OC patients and 2278 population-matched controls using next-generation sequencing. We revealed germline mutations in 18 OC/BC predisposition genes in 32.0% of patients and in 2.5% of controls. Mutations in BRCA1/BRCA2, RAD51C/RAD51D, BARD1, and mismatch repair genes conferred high OC risk (OR > 5). Mutations in BRIP1 and NBN were associated with moderate risk (both OR = 3.5). BRCA1/2 mutations dominated in almost all clinicopathological subgroups including sporadic borderline tumors of ovary (BTO). Analysis of remaining 201 genes revealed somatic mosaics in PPM1D and germline mutations in SHPRH and NAT1 associating with a high/moderate OC risk significantly; however, further studies are warranted to delineate their contribution to OC development in other populations. Our findings demonstrate the high proportion of patients with hereditary OC in Slavic population justifying genetic testing in all patients with OC, including BTO.

Recommendations for Preventive Care for Women with Rare Genetic Cause of Breast and Ovarian Cancer.

An inherited predisposition to breast cancer underlies 5-10% of breast tumors. High-risk BRCA1 and BRCA2 genes result in an 85% lifetime risk of breast cancer and a 20-60% lifetime risk of ovarian cancer. Next-generation sequencing or massive parallel sequencing are now established testing methods that enable screening for many genes that predispose to heterogeneous hereditary cancer syndromes (22 genes are required by the health insurance companies). In addition to BRCA1 and BRCA2, inherited mutations in other genes predispose to breast and/or ovarian cancer. High-risk breast cancer genes include TP53, STK11, CDH1, PTEN, PALB2, and NF1, while moderate-risk (2-4 times increased risk) breast cancer genes include ATM, CHEK2, and NBN. Moderate risk is also suggested for Lynch syndrome, MUTYH, BRIP1, RAD51C, RAD51D, BARD1, FANCA, FANCC, FANCM, BLM, WRN genes. In heterozygotes for other recessive syndromes the risk of developing breast cancer is subject to current research. Low-risk genes are (mostly) irrelevant from a clinical perspective. Other genes that increase the risk of ovarian cancer include the genes for Lynch syndrome, the BRIP1, RAD51C and RAD51D genes. Preventive care should be proposed based on assumed cumulative breast cancer risk (see http: //www.mamo.cz): a risk of >20% for BRCA1/2, TP53, PTEN, STK11, CDH1, PALB2, CHEK2, ATM, and NF1; and a risk of 10-20% for BRIP1, RAD51C, RAD51B, BARD1, FANCA, FANCC, FANCM, NBN, BLM, and WRN. The genetic risk should be assessed by a geneticist and be based on inherited mutations and empirical risk according to family history. Prophylactic mastectomy is considered for high-risk gene carriers but not for moderate-risk gene carriers; however, it may be considered if there is an underlying family history, a risk of parenchyma of the mammary gland, or other risk factors. Ovarian cancer risk increases significantly in carriers of the BRIP1, RAD51C, and RAD51D genes. For prevention of ovarian cancer, prophylactic salpingo-oophorectomy is an important component of preventive care. In ovarian cancer families with no identified risk germline mutation, preventive salpingo-oophorectomy is not routinely recommended but may be considered as the only efficient method of prevention due to the increased empirical risk (4 times) of ovarian cancer in first-degree relatives. Supported by the grant project MH CZ - RVO (MMCI, 00209805), AZV 15-27695A and AZV 16-29959A. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 17. 5. 2019 Accepted: 31. 5. 2019.

Twenty Years of BRCA1 and BRCA2 Molecular Analysis at MMCI - Current Developments for the Classification of Variants.

BACKGROUND: Deleterious mutations in the BRCA1 and BRCA2 genes account for a considerable proportion of dominantly inherited breast and ovarian cancer susceptibility. The laboratory interpretation has always been dependent on the information available at the time of the report conclusion. The aim of this study has been to review the results from the BRCA testing at Masaryk Memorial Cancer Institute (MMCI). PATIENTS AND METHODS: Patients with suspected hereditary predisposition to breast/ovarian cancer, belonging to 7,400 families, were referred by genetic counsellors for BRCA1 and BRCA2 mutation testing at the MMCI from 1999 to the beginning of 2018. Various methods have been used over 20 years of laboratory practice - starting with the Protein Truncation Test and Heteroduplex Analysis via the High Resolution Melting analysis and Sanger sequencing up to Next Generation Sequencing. RESULTS: BRCA1 and BRCA2 mutation screening resulted in the identification of 1,021 families with a germline high-risk BRCA1 mutation and 497 families carrying a high-risk BRCA2 mutation, representing a mutation detection rate of 20.5%. A broad spectrum of unique mutations classified as pathogenic or likely pathogenic has been detected in both genes - 124 in the BRCA1 and 123 in the BRCA2 gene. Other sequence variants (96 unique variants in the BRCA1 and 126 in the BRCA2 gene) have been revised and classified as benign or likely benign. The other 82 unique variants remain classified as of uncertain significance mainly due to a lack of information for inclusion in other groups. All the results are summarised in the tables, including the reasons for their classification. CONCLUSION: The clinical classification of rare sequence variants identified in the high-risk breast cancer susceptibility genes BRCA1 and BRCA2 is essential for appropriate genetic counselling. Here we present an overview of BRCA mutation frequencies in our region and the retrospective evaluation and eventually reclassification of previously reported rare variants in light of recent findings.

GAPPS - Gastric Adenocarcinoma and Proximal Polyposis of the Stomach Syndrome in 8 Families Tested at Masaryk Memorial Cancer Institute - Prevention and Prophylactic Gastrectomies.

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is a rare variant of familial adenomatous polyposis. It is an autosomal-dominant cancer-predisposition syndrome with massive polyposis of the stomach and a significant risk of gastric adenocarcinoma. Li et al., 2016, described point mutations in the Ying Yang 1 binding site of the APC gene 1B promoter associated with GAPPS syndrome. The first GAPPS syndrome in a Czech family was described in 2016. At Masaryk Memorial Cancer Institute, GAPPS syndrome was diagnosed in eight families using Sanger sequencing. In all families, one mutation in promoter 1B of APC gene NM_001127511: c.-191T>C was detected. This mutation was not found in any patient with multiple colon polyposis without a detected classic mutation in the APC gene. In total, 24 carriers of this mutation in promoter 1B of the APC gene were detected. Out of those 24 carriers, 20 had massive gastric polyposis with more than 100 fundic glandular polyps diagnosed between the age of 22 and 65, 5 had already died of adenocarcinoma of the stomach (at the ages of 29, 40, 59, 60 and 64, respectively) and another woman was treated at the age of 29. Two female carriers do not yet have polyposis of the stomach at the ages of 31 and 65, respectively; one female carrier has incipient polyposis at the age of 58. A male carrier does not have any clinical symptoms, gastroscopy was not indicated because of his age. Prophylactic total gastrectomy with D2 lymphadenectomy has already been performed 6 times at Masaryk Memorial Cancer Institute, in 5 cases without adenocarcinoma at the ages of 27, 34, 44, 51 and 66, respectively; in one female carrier adenocarcinoma of the stomach was detected in a histology specimen. Two prophylactic gastrectomies with D1 lymphadenectomy were performed at University Hospital Brno at the ages of 42 and 50, respectively. In the Czech Republic point mutation c.-191T>C (rs879253783) in the 1B promoter of the APC gene is a frequent cause of gastric polyposis with a high risk of gastric adenocarcinoma, even at a young age. Positively tested individuals are recommended to high-risk oncology clinic. A necessary part of the discussion with the patient is information about a preventive gastrectomy.

BAP1 Syndrome - Predisposition to Malignant Mesothelioma, Skin and Uveal Melanoma, Renal and Other Cancers.

BACKGROUND: BAP1 syndrome is an autosomal dominant hereditary cancer syndrome associated with increased risk of malignant mesothelioma; uveal and cutaneous melanoma; kidney cancer; lung adenocarcinoma; meningioma; basaliomas; and breast, ovarian, and prostate tumors. The BAP1 gene (BRCA1-associated protein 1) is a tumor suppressor gene involved in DNA repair via homologous recombination. BAP1 regulates the cell cycle, differentiation, DNA damage responses, and cell proliferation through deubiquitination. Somatic mutations in the BAP1 gene are common in many types of tumors. OBSERVATION: Two families harboring a germline mutation in the BAP1 gene were diagnosed at Masaryk Memorial Cancer Institute (MMCI). A 27-year-old index female from one family was followed-up for multiple nevi. Her mother and uncle had malignant mesothelioma, and her maternal grandmother had uveal melanoma. The index case tested positive for a BAP1 (NM_004656.2): c.217delG/p.Asp73Metfs*5 frame-shift mutation. The melanoma was removed at the age of 28 and 31. In the second family, an 11-year-old index female had two nevi removed from her head, and a spitzoid-type skin lesion was diagnosed at the age of 11. Her 34-year-old mother had multiple nevi, and a skin lesion of spitzoid-type was removed from the abdomen. Both patients harbored a BAP1 (NM_004656.2): c.123-1G>T acceptor splice site mutation (IARC [International Agency for Research on Cancer] class 4 [probably pathogenic]). Preventive measures for BAP1 syndrome should include known risks for cancer. Tumors occur early and repeatedly. At the MMCI, we recommend physical examination by an oncologist, eyes and skin examination, every 6 months; whole-body magnetic resonance imaging, including the central nervous system, every year (or low-dose computed tomography/chest and abdomen magnetic resonance imaging); annual abdominal ultrasound, breast ultrasound, or mammography; a gynecological ultrasound examination every 6 months; colonoscopy starting at the age of 45; and other suitable surveillances based on family history. CONCLUSION: BAP1 syndrome is a complex cancer syndrome with a high risk of rare malignant mesothelioma, malignant skin and uveal melanoma, spitzoid-type skin lesions, and other tumors. Detection of this syndrome is essential for the survival of high-risk individuals. Supported by the grant project MH CZ - RVO (MMCI, 00209805). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 21. 5. 2019 Accepted: 6. 6. 2019.