ENIGMA CHEK2gether Project: A Comprehensive Study Identifies Functionally Impaired CHEK2 Germline Missense Variants Associated with Increased Breast Cancer Risk

PURPOSE: Germline pathogenic variants in CHEK2 confer moderately elevated breast cancer risk (odds ratio, OR ∼ 2.5), qualifying carriers for enhanced breast cancer screening. Besides pathogenic variants, dozens of missense CHEK2 variants of uncertain significance (VUS) have been identified, hampering the clinical utility of germline genetic testing (GGT). EXPERIMENTAL DESIGN: We collected 460 CHEK2 missense VUS identified by the ENIGMA consortium in 15 countries. Their functional characterization was performed using CHEK2-complementation assays quantifying KAP1 phosphorylation and CHK2 autophosphorylation in human RPE1-CHEK2-knockout cells. Concordant results in both functional assays were used to categorize CHEK2 VUS from 12 ENIGMA case-control datasets, including 73,048 female patients with breast cancer and 88,658 ethnicity-matched controls. RESULTS: A total of 430/460 VUS were successfully analyzed, of which 340 (79.1%) were concordant in both functional assays and categorized as functionally impaired (N = 102), functionally intermediate (N = 12), or functionally wild-type (WT)-like (N = 226). We then examined their association with breast cancer risk in the case-control analysis. The OR and 95% CI (confidence intervals) for carriers of functionally impaired, intermediate, and WT-like variants were 2.83 (95% CI, 2.35-3.41), 1.57 (95% CI, 1.41-1.75), and 1.19 (95% CI, 1.08-1.31), respectively. The meta-analysis of population-specific datasets showed similar results. CONCLUSIONS: We determined the functional consequences for the majority of CHEK2 missense VUS found in patients with breast cancer (3,660/4,436; 82.5%). Carriers of functionally impaired missense variants accounted for 0.5% of patients with breast cancer and were associated with a moderate risk similar to that of truncating CHEK2 variants. In contrast, 2.2% of all patients with breast cancer carried functionally wild-type/intermediate missense variants with no clinically relevant breast cancer risk in heterozygous carriers

Inheritance of deleterious mutations at both BRCA1 and BRCA2 in an international sample of 32,295 women

Background: Most BRCA1 or BRCA2 mutation carriers have inherited a single (heterozygous) mutation. Transheterozygotes (TH) who have inherited deleterious mutations in both BRCA1 and BRCA2 are rare, and the consequences of transheterozygosity are poorly understood. Methods: From 32,295 female BRCA1/2 mutation carriers, we identified 93 TH (0.3 %). "Cases" were defined as TH, and "controls" were single mutations at BRCA1 (SH1) or BRCA2 (SH2). Matched SH1 "controls" carried a BRCA1 mutation found in the TH "case". Matched SH2 "controls" carried a BRCA2 mutation found in the TH "case". After matching the TH carriers with SH1 or SH2, 91 TH were matched to 9316 SH1, and 89 TH were matched to 3370 SH2. Results: The majority of TH (45.2 %) involved the three common Jewish mutations. TH were more likely than SH1 and SH2 women to have been ever diagnosed with breast cancer (BC; p = 0.002). TH were more likely to be diagnosed with ovarian cancer (OC) than SH2 (p = 0.017), but not SH1. Age at BC diagnosis was the same in TH vs. SH1 (p = 0.231), but was on average 4.5 years younger in TH than in SH2 (p < 0.001). BC in TH was more likely to be estrogen receptor (ER) positive (p = 0.010) or progesterone receptor (PR) positive (p = 0.013) than in SH1, but less likely to be ER positive (p < 0.001) or PR positive (p = 0.012) than SH2. Among 15 tumors from TH patients, there was no clear pattern of loss of heterozygosity (LOH) for BRCA1 or BRCA2 in either BC or OC. Conclusions: Our observations suggest that clinical TH phenotypes resemble SH1. However, TH breast tumor marker characteristics are phenotypically intermediate to SH1 and SH2

Breast cancer risk variants at 6q25 display different phenotype associations and regulate ESR1, RMND1 and CCDC170.

We analyzed 3,872 common genetic variants across the ESR1 locus (encoding estrogen receptor α) in 118,816 subjects from three international consortia. We found evidence for at least five independent causal variants, each associated with different phenotype sets, including estrogen receptor (ER(+) or ER(-)) and human ERBB2 (HER2(+) or HER2(-)) tumor subtypes, mammographic density and tumor grade. The best candidate causal variants for ER(-) tumors lie in four separate enhancer elements, and their risk alleles reduce expression of ESR1, RMND1 and CCDC170, whereas the risk alleles of the strongest candidates for the remaining independent causal variant disrupt a silencer element and putatively increase ESR1 and RMND1 expression.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/ng.352

Inheritance of deleterious mutations at both BRCA1 and BRCA2 in an international sample of 32,295 women

Background: Most BRCA1 or BRCA2 mutation carriers have inherited a single (heterozygous) mutation. Transheterozygotes (TH) who have inherited deleterious mutations in both BRCA1 and BRCA2 are rare, and the consequences of transheterozygosity are poorly understood. Methods: From 32,295 female BRCA1/2 mutation carriers, we identified 93 TH (0.3 %). "Cases" were defined as TH, and "controls" were single mutations at BRCA1 (SH1) or BRCA2 (SH2). Matched SH1 "controls" carried a BRCA1 mutation found in the TH "case". Matched SH2 "controls" carried a BRCA2 mutation found in the TH "case". After matching the TH carriers with SH1 or SH2, 91 TH were matched to 9316 SH1, and 89 TH were matched to 3370 SH2. Results: The majority of TH (45.2 %) involved the three common Jewish mutations. TH were more likely than SH1 and SH2 women to have been ever diagnosed with breast cancer (BC; p = 0.002). TH were more likely to be diagnosed with ovarian cancer (OC) than SH2 (p = 0.017), but not SH1. Age at BC diagnosis was the same in TH vs. SH1 (p = 0.231), but was on average 4.5 years younger in TH than in SH2 (p <0.001). BC in TH was more likely to be estrogen receptor (ER) positive (p = 0.010) or progesterone receptor (PR) positive (p = 0.013) than in SH1, but less likely to be ER positive (p <0.001) or PR positive (p = 0.012) than SH2. Among 15 tumors from TH patients, there was no clear pattern of loss of heterozygosity (LOH) for BRCA1 or BRCA2 in either BC or OC. Conclusions: Our observations suggest that clinical TH phenotypes resemble SH1. However, TH breast tumor marker characteristics are phenotypically intermediate to SH1 and SH2.Peer reviewe

Genome-wide association study identifies 25 known breast cancer susceptibility loci as risk factors for triple-negative breast cancer

Triple-negative (TN) breast cancer is an aggressive subtype of breast cancer associated with a unique set of epidemiologic and genetic risk factors. We conducted a two-stage genome-wide association study of TN breast cancer (stage 1: 1529 TN cases, 3399 controls; stage 2: 2148 cases, 1309 controls) to identify loci that influence TN breast cancer risk. Variants in the 19p13.1 and PTHLH loci showed genome-wide significant associations (P < 5 × 10− 8) in stage 1 and 2 combined. Results also suggested a substantial enrichment of significantly associated variants among the single nucleotide polymorphisms (SNPs) analyzed in stage 2. Variants from 25 of 74 known breast cancer susceptibility loci were also associated with risk of TN breast cancer (P < 0.05). Associations with TN breast cancer were confirmed for 10 loci (LGR6, MDM4, CASP8, 2q35, 2p24.1, TERT-rs10069690, ESR1, TOX3, 19p13.1, RALY), and we identified associations with TN breast cancer for 15 additional breast cancer loci (P < 0.05: PEX14, 2q24.1, 2q31.1, ADAM29, EBF1, TCF7L2, 11q13.1, 11q24.3, 12p13.1, PTHLH, NTN4, 12q24, BRCA2, RAD51L1-rs2588809, MKL1). Further, two SNPs independent of previously reported signals in ESR1 [rs12525163 odds ratio (OR) = 1.15, P = 4.9 × 10− 4] and 19p13.1 (rs1864112 OR = 0.84, P = 1.8 × 10− 9) were associated with TN breast cancer. A polygenic risk score (PRS) for TN breast cancer based on known breast cancer risk variants showed a 4-fold difference in risk between the highest and lowest PRS quintiles (OR = 4.03, 95% confidence interval 3.46–4.70, P = 4.8 × 10− 69). This translates to an absolute risk for TN breast cancer ranging from 0.8% to 3.4%, suggesting that genetic variation may be used for TN breast cancer risk prediction

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Hereditary Breast Cancer: The Era of New Susceptibility Genes

Breast cancer is the most common malignancy among females. 5%–10% of breast cancer cases are hereditary and are caused by pathogenic mutations in the considered reference BRCA1 and BRCA2 genes. As sequencing technologies evolve, more susceptible genes have been discovered and BRCA1 and BRCA2 predisposition seems to be only a part of the story. These new findings include rare germline mutations in other high penetrant genes, the most important of which include TP53 mutations in Li-Fraumeni syndrome, STK11 mutations in Peutz-Jeghers syndrome, and PTEN mutations in Cowden syndrome. Furthermore, more frequent, but less penetrant, mutations have been identified in families with breast cancer clustering, in moderate or low penetrant genes, such as CHEK2, ATM, PALB2, and BRIP1. This paper will summarize all current data on new findings in breast cancer susceptibility genes

Το ζήτημα της συμμετοχής των Δυτικών Βαλκανίων στην Ευρωπαϊκή Ένωση

Οι προσπάθειες για την ένταξη των χωρών της περιοχής των Δυτικών Βαλκανίων στην Ευρωπαϊκή Ένωση ανήκουν σε ένα ευρύτερο πλαίσιο ενεργειών της ένωσης, με σκοπό τη διάδοση των ευρωπαϊκών ιδεών και κυρίως των αξιών της ΕΕ, που αφορούν στη δημοκρατία, τα ανθρώπινα δικαιώματα και το κράτος δικαίου, θεμελιώδεις αρχές στις οποίες, ως επί το πλείστον, στηρίζονται οι συνθήκες που έχουν υπογραφεί μεταξύ των χωρών που ασπάζονται την ευρωπαϊκή συνεργασία. Οι υπεύθυνοι χάραξης πολιτικής της ΕΕ επιδιώκουν τη διεύρυνσή της, καθώς, όπως πιστεύεται, η αλληλεξάρτηση των χωρών και η μεταξύ τους συνεργασία, που επικυρώνεται μέσω των συνθηκών, θα συμβάλει στη διάδοση της ειρήνης, κατά κύριο λόγο, αλλά και της δημοκρατίας στο μεγαλύτερο μέρος της ευρωπαϊκής ηπείρου. Η οικονομική κρίση του 2008 επηρέασε βαθιά την οικονομική, αλλά και τη γενικότερη πορεία της ΕΕ έως τώρα. Τα σχέδια για διεύρυνση της ένωσης σταματούν απότομα, όπως και το ενδιαφέρον των κρατών-μελών γι’ αυτά, τα οποία κράτη χαρακτηρίζονται από την εσωστρέφεια και τα φαινόμενα εθνικισμού που κατακλύζουν τις πολιτικές ηγεσίες αρκετών από αυτά. Από την άλλη πλευρά, τα υποψήφια προς ένταξη κράτη των Δυτικών Βαλκανίων, αντιμετωπίζοντας τα ίδια οικονομικές δυσκολίες και κοινωνικές συγκρούσεις και αναταραχές, αντιλαμβάνονται την επιφυλακτική στάση των στελεχών της ΕΕ και απογοητεύονται εξίσου από τις εθνικιστικές εκδηλώσεις ορισμένων από τα κράτη-μέλη. Ως συνέπεια όλων αυτών προκύπτει ο ευρωσκεπτικισμός, που στην ουσία του είναι η αμφισβήτηση της χρησιμότητας του θεσμού της ΕΕ, αλλά και η καχυποψία ως προς την ανιδιοτέλεια των αρχών και κανόνων που εκπροσωπεί. Εντείνεται όλο και περισσότερο η πεποίθηση πως η συμμετοχή στην ένωση δε συνεπάγεται την ευδαιμονία.Efforts to integrate the countries of the Western Balkans into the European Union (EU) are part of a wider framework of the Union, with the aim of disseminating European ideas and, above all, EU values of democracy, human rights and the rule of law, fundamental principles on which, for the most part, the treaties signed between the countries embracing European cooperation are based. EU policymakers are pushing for enlargement, as it is believed that the interdependence of countries and the co-operation between them, ratified through the treaties, will contribute to the spread of peace, mainly, but also to democracy for the most part of the European continent. The economic crisis of 2008 has profoundly affected the economic and general course of the EU so far. Plans to enlarge the union come to an abrupt halt, as do member states&apos; interest in them, which are characterized by introversion and nationalism that pervade the political leaderships of many of them. On the other hand, the candidate countries of the Western Balkans, facing the same economic difficulties and social conflicts and unrest, are aware of the cautious attitude of EU officials and are equally disappointed by the nationalist manifestations of some of the Member States. The consequence of all this is Euroscepticism, which in essence is the questioning of the usefulness of the EU institution, but also the suspicion as to the selflessness of the principles and rules it represents. The belief that participation in the union does not imply happiness is growing

Identification of new alleles in genes that predispose to breast and ovarian cancer

Breast cancer is the most common form of cancer affecting women in the developed world. Although approximately 5-10% of breast cancer cases are attributed in mutations in BRCA1 and BRCA2 genes, a significant fraction of these cases is explained by mutations in other high and medium penetrant genes. Consequently, genetic analysis of hereditary breast/ovarian cancer plays an important role in understanding the molecular mechanisms leading to carcinogenesis and it significantly contributes to the clinical management of patients with breast/ovarian cancer. The aim of the present thesis is the identification and characterization of novel mutations in breast cancer susceptibility genes in patients with severe breast/ovarian cancer family history, the detection of new large genomic rearrangements as well as the evaluation of mutations that appear frequently in Greek population. The total number of breast cancer patients tested for point mutations in the BRCA1 and BRCA2 genes was 252 and 196, respectively. Pathogenic mutations in the BRCA1 gene were detected in 7.53% of patients while 8 women (4.1%) carried a BRCA2 pathogenic mutation. In addition, 4 unclassified variants were identified in the BRCA1 gene (1.58%) and 2 in the BRCA2 gene, respectively. Moreover, all the patients that were negative for mutations, were tested for the presence of large genomic rearrangements by another method and consequently two patients carried a deletion encompassing both exons 23 and 24 of the BRCA1 gene. Furthermore, in a series of 2,092 high-risk families fully screened for BRCA1 and BRCA2 germline mutations, the deletion of exons 23 and 24 of the BRCA1 gene was found in 35 families (1.68%) and haplotype analysis showed that it was a founder mutation for the Greek population. All the BRCA1 carriers were originated from the Aegean islands and the Asia Minor coast. Moreover, 226 patients with a strong family history of breast/ovarian cancer were analyzed by massively parallel sequencing using BROCA panel, which captured the entire loci of 50 genes. Of the 226 patients, 28 (12.4%) carried loss-of-function mutations in one of the 50 genes while 20 carried variants of unknown clinical significance. Additionally, 40 women diagnosed with early onset breast and/or ovarian cancer or with a severe family history were analyzed using “TruSight Cancer panel” that captured the entire loci of 94 genes. The experimental approach was carried out at Molecular diagnostics laboratory, NCSR Demokritos. In total, two pathogenic mutations were identified in 2 patients while 4 patients carried unclassified variants. Moreover, a novel BRCA2 LGR encompassing exons 12 and 13 was identified in the Greek population. Firstly, the genomic breakpoints for the deletion were determined by Long range PCR and subsequently 2,386 women diagnosed with breast cancer were screened by a customized PCR assay. The deletion was detected in 0.25% (6/2,386) of cases while haplotype analysis showed that it was a Greek founder mutation. All mutation carriers were originated from Crete Island.CHEK2 is a well-studied breast cancer susceptibility gene, beyond BRCA1 and BRCA2 genes. In the present study, the medium penetrance gene CHEK2 was analyzed in order to characterize the mutation spectrum in Greek population. Initially, 2,408 women diagnosed with breast cancer were screened for CHEK2 c.1100delC mutation and it was detected in 0.16% (4 of 2,408) of females, indicating that the specific allele did not contribute substantially to hereditary breast cancer in patients of Greek descent. Moreover, a novel CHEK2 LGR of a ~7.5kb deletion encompassing exon 6 was identified by BROCA panel. Subsequently, the genomic breakpoints of the latter were determined and 2,355 breast cancer patients and 1,580 controls were genotyped by a custom-designed PCR. The deletion was detected in 0.22% (5/2,355) of patients but in none of the 1,580 controls while haplotype analysis showed that all carriers shared a common disease-associated haplotype for a stretch of 1,850kb, suggesting a single common ancestor and a founder mutation for the Greek population. All carriers were originated from Western Greece. In silico analysis, results of CHEK2-yeast functional assay and structure–function relationship prediction were consistent with impairment of the mutant protein. An important aspect of the pathogenicity of this mutation was the effect that had been confirmed on the RNA level, where an aberrant isoform was being produced. It is quite possible that this mutation has a dominant-negative effect, rather than being destroyed by nonsense mRNA decay.In conclusion, in the present thesis three rare genomic events were characterized in BRCA1, BRCA2 and CHEK2 genes that were identified in ~2% of Greek women diagnosed with early onset breast cancer or/and with severe breast/ovarian cancer family history. The aforementioned genomic rearrangements were present in specific regions and showed geographical distribution, thus this information is useful in diagnostic level. Moreover, massively parallel sequencing of many genes was developed resulting in the identification of many genetic alterations in well-studied as well as in new breast cancer susceptibility genes, using next generation sequencing technology. Consequently, through these technologies, a significant progress was made in broadening the spectrum of breast cancer-related genes (e.g. CHEK2 and PALB2), beyond BRCA1 and BRCA2, resulting in better understanding of the underlying mechanisms of familial breast cancer in Greece.Ο καρκίνος του μαστού αποτελεί τον πιο συνηθισμένο τύπο καρκίνου που διαγιγνώσκεται στις γυναίκες στις ανεπτυγμένες χώρες. Περίπου 5-10% των περιστατικών καρκίνου του μαστού οφείλεται σε μεταλλάξεις των γονιδίων BRCA1 και BRCA2, ενώ ένα σημαντικό μέρος αυτών εξηγείται από μεταλλάξεις άλλων γονιδίων, υψηλής και μεσαίας διεισδυτικότητας. Έτσι, η γονιδιακή ανάλυση στον κληρονομικό καρκίνο του μαστού συμβάλει στην κατανόηση των μοριακών μηχανισμών της καρκινογένεσης αλλά και τη βελτιστοποίηση της διαχείρισης των ασθενών.Σκοπός της παρούσας διδακτορικής διατριβής αποτελεί η ταυτοποίηση και ο χαρακτηρισμός νέων μεταλλάξεων σε γονίδια προδιάθεσης καρκίνου του μαστού σε ασθενείς με βεβαρυμμένο οικογενειακό ή ατομικό ιστορικό, η ανίχνευση σπάνιων γενετικών φαινομένων, καθώς και ο χαρακτηρισμός μεταλλάξεων που εμφανίζονται με μεγάλη συχνότητα στον Ελληνικό πληθυσμό. Αρχικά αναλύθηκε το γενετικό υλικό 252 και 196 ασθενών με την αλληλούχιση κατά Sanger για μεταλλάξεις του γονιδίου BRCA1 και του γονιδίου BRCA2, αντίστοιχα όπου και ανιχνεύθηκαν 19 (7,53%) και 8 (4,1%) παθογόνοι μεταλλάξεις, αντίστοιχα. Οι ασθενείς εκείνες που ήταν αρνητικές για μεταλλάξεις, υποβλήθηκαν σε έλεγχο με ανεξάρτητη μέθοδο για την παρουσία γονιδιακών αναδιατάξεων, όπου και ανιχνεύθηκε απαλοιφή των εξονίων 23 και 24 του γονιδίου BRCA1 σε δύο ασθενείς. Στη συνέχεια, προσδιορίσθηκε η συχνότητα της απαλοιφής αυτής σε 2.092 ασθενείς με σοβαρό ιστορικό καρκίνου μαστού/ωοθηκών, η οποία υπολογίστηκε στο 1,68%. Η ανάλυση απλοτύπων έδειξε πως αποτελεί ιδρυτική μετάλλαξη για τον Ελληνικό πληθυσμό και πιο συγκεκριμένα, με καταβολή από τα νησιά του Αιγαίου και την περιοχή της Μικράς Ασίας. Προκειμένου να αποσαφηνιστεί το γονιδιακό υπόβαθρο 226 ασθενών με ηλικία διάγνωσης καρκίνου <35 ετών ή/και βεβαρυμμένο οικογενειακό ιστορικό καρκίνου μαστού/ωοθηκών χρησιμοποιήθηκε η μεθοδολογία της νέας γενιάς αλληλούχισης (Next Generation Sequencing) και πιο συγκεκριμένα το BROCA πάνελ, το οποίο αναλύει ταυτόχρονα 50 γονίδια προδιάθεσης καρκίνου. Συνολικά, ανιχνεύθηκαν 29 παθογόνοι μεταλλάξεις σε 28 ασθενείς (12,4%) στα υπό μελέτη γονίδια προδιάθεσης, ενώ 20 ασθενείς έφεραν γενετικές αλλαγές αγνώστου παθογένειας. Εν συνεχεία, αναλύθηκαν 40 δείγματα γυναικών με σοβαρό οικογενειακό ιστορικό ή νεαρή ηλικία διάγνωσης (<45 ετών) καρκίνου μαστού χρησιμοποιώντας το γονιδιακό πάνελ TruSight Cancer panel, το οποίο περιλαμβάνει 94 γονίδια προδιάθεσης. Κατά την ανάλυση αυτή ανιχνεύθηκαν 2 παθογόνοι μεταλλάξεις και 4 γενετικές αλλαγές αγνώστου παθογένειας. Μέσω των παραπάνω αναλύσεων, ανιχνεύθηκε μία καινοφανής –για τον Ελληνικό πληθυσμό- γονιδιακή αναδιάταξη στο γονίδιο BRCA2, κατά την οποία απαλείφονται τα εξόνια 12 και 13 του γονιδίου. Στη συνέχεια, προσδιορίσθηκαν τα ακριβή σημεία θραύσης της μετάλλαξης, ενώ αναλύθηκαν 2.386 δείγματα DNA γυναικών με καρκίνο μαστού, εκ των οποίων οι 6 (6/2.386; 0,25%) έφεραν την εν λόγω μετάλλαξη. Η περαιτέρω ανάλυση απλοτύπων κατέδειξε πως αποτελεί ιδρυτική μετάλλαξη για τον Ελληνικό πληθυσμό, ενώ όλα τα άτομα που την έφεραν κατάγονταν από την Κρήτη. Το γονίδιο CHEK2 αποτελεί ένα από τα βασικά γονίδια προδιάθεσης καρκίνου μαστού, πέραν των γονιδίων BRCA1 & BRCA2. Στο πλαίσιο της παρούσας διατριβής, αξιολογήθηκε η συνεισφορά των μεταλλάξεων του γονιδίου αυτού στον Ελληνικό πληθυσμό. Αρχικά, ελέγχθηκαν 2.408 γυναίκες με καρκίνο του μαστού για τη μετάλλαξη c.1100delC, η οποία απαντάται σε υψηλή συχνότητα σε πληθυσμούς της Βόρειας Ευρώπης (~1% στο γενικό πληθυσμό), ενώ διαφάνηκε ότι συνεισφέρει σε πολύ μικρό βαθμό στην προδιάθεση για καρκίνο του μαστού στις Ελληνίδες ασθενείς, μιας και ανιχνεύθηκε στο 0,16% των ασθενών που μελετήθηκαν. Στη συνέχεια και με δεδομένη την ανίχνευση μιας καινοφανής γονιδιακής αναδιάταξης του γονιδίου CHEK2, κατά την οποία απαλείφεται το εξόνιο 6, ελέχθηκαν 2.355 ασθενείς με καρκίνο μαστού. Η εν λόγω μετάλλαξη ανιχνεύθηκε στο 0.22% των ασθενών, ενώ η ανάλυση απλοτύπων έδειξε πως αποτελεί ιδρυτική μετάλλαξη για τον Ελληνικό πληθυσμό και με συγκεκριμένη καταγωγή την περιοχή της Δυτικής Ελλάδας. Η παθογένεια της συγκεκριμένης απαλοιφής προσδιορίσθηκε μέσω τεσσάρων διαφορετικών μεθόδων. Αρχικά, η in silico ανάλυση κατέδειξε την επιβλαβή της φύση, ενώ η ανάλυση της επίδρασης της μετάλλαξης στο μάτισμα του mRNA έδειξε ότι παράγεται ένα επιπλέον θραύσμα μικρότερου μεγέθους, το οποίο αντιστοιχεί σε μεταλλαγμένο mRNA από το οποίο απαλείφεται το εξόνιο 6. Επιπλέον, τόσο η λειτουργική δοκιμασία των κυττάρων ζύμης, όσο και η μελέτη της επίδρασης της μετάλλαξης στη δομή της πρωτεΐνης έδειξαν πως η γονιδιακή αναδιάταξη αλλάζει τη λειτουργία της πρωτεΐνης, καταργώντας την ενεργότητα κινάσης δεδομένης της απαλοιφής μιας α-έλικας στην περιοχή αυτή. Συνοψίζοντας, στην παρούσα διατριβή χαρακτηρίσθηκαν τρία σπάνια γενετικά φαινόμενα στα γονίδια BRCA1, BRCA2 και CHEK2 τα οποία ανιχνεύθηκαν συνολικά στο ~2% των Ελληνίδων ασθενών με νεαρή ηλικία διάγνωσης ή/και ιστορικό καρκίνου μαστού/ωοθηκών. Οι εν λόγω γονιδιακές αναδιατάξεις παρουσιάζουν γεωγραφική κατανομή, γεγονός που καθιστά την πληροφορία αυτή αξιοποιήσιμη σε διαγνωστικό επίπεδο. Επιπρόσθετα, αναπτύχθηκε η τεχνογνωσία της παράλληλης ανάλυσης πολλών γονιδίων, η οποία οδηγεί στην ανίχνευση πολλών γενετικών αλλαγών σε γνωστά και νέα γονίδια προδιάθεσης καρκίνου με την τεχνολογία της επόμενης γενεάς αλληλούχισης. Έτσι, εκτός από τη μελέτη των δύο βασικών γονιδίων προδιάθεσης καρκίνου μαστού (BRCA1 και BRCA2) καταγράφηκε και η συνεισφορά άλλων γονιδίων όπως τα CHEK2 και PALB2, γεγονός που συνέβαλε στην καλύτερη κατανόηση του γενετικού υπόβαθρου του κληρονομικού καρκίνου του μαστού στον Ελληνικό πληθυσμό