Insights into the Peritumoural Brain Zone of Glioblastoma: CDK4 and EXT2 May Be Potential Drivers of Malignancy.

Despite the efforts made in recent decades, glioblastoma is still the deadliest primary brain cancer without cure. The potential role in tumour maintenance and progression of the peritumoural brain zone (PBZ), the apparently normal area surrounding the tumour, has emerged. Little is known about this area due to a lack of common definition and due to difficult sampling related to the functional role of peritumoural healthy brain. The aim of this work was to better characterize the PBZ and to identify genes that may have role in its malignant transformation. Starting from our previous study on the comparison of the genomic profiles of matched tumour core and PBZ biopsies, we selected CDK4 and EXT2 as putative malignant drivers of PBZ. The gene expression analysis confirmed their over-expression in PBZ, similarly to what happens in low-grade glioma and glioblastoma, and CDK4 high levels seem to negatively influence patient overall survival. The prognostic role of CDK4 and EXT2 was further confirmed by analysing the TCGA cohort and bioinformatics prediction on their gene networks and protein-protein interactions. These preliminary data constitute a good premise for future investigations on the possible role of CDK4 and EXT2 in the malignant transformation of PBZ.

Tubal histopathological abnormalities in BRCA1/2 mutation carriers undergoing prophylactic salpingo-oophorectomy: a case-control study.

OBJECTIVE: To describe tubal histopathological abnormalities in women with germline BRCA1/2 mutations and in controls. METHODS: Consecutive women with BRCA1/2 mutations undergoing bilateral salpingo-oophorectomy between 2010 and 2020 in two centers (San Gerardo Hospital, Monza and San Matteo Hospital, Pavia) were considered in this analysis and compared with controls who had the same surgical procedure for benign conditions. Frequency of p53 signature, serous tubal intraepithelial carcinoma, and high-grade serous ovarian cancer were compared between the two groups. RESULTS: A total of 194 women with pathogenic BRCA1/2 mutations underwent prophylactic salpingo-oophorectomy. Of these, 138 women (71%) had a completely negative histological examination, while in 56 (29%) patients an ovarian or tubal alteration was reported. Among controls, 84% of patients had a p53wt signature, while 16% had a p53 signature. There was no difference in the frequency of a p53 signature between cases and controls; however, women with BRCA1/2 mutations were more likely to have pre-malignant or invasive alterations of tubal or ovarian epithelium (p=0.015). Among mutation carriers, older age both at genetic testing and at surgery was associated with an increased risk of having malignancies (OR=1.07, p=0.006 and OR=1.08, p=0.004, respectively). The risk of malignancy seems to be increased in patients with a familial history of high-grade serous ovarian cancer. Previous therapy with tamoxifen was significantly more frequent in patients with malignant lesions (40.0% vs 21.3%, p=0.006). CONCLUSION: We found that a p53 signature is a frequent finding both in BRCA1/2 mutation carriers and in controls, while pre-invasive and invasive lesions are more frequent in BRCA1/2 mutation carriers. Genetic and clinical characteristics are likely to affect the progression to malignancy.

Characterization of Chromosomal Breakpoints in 12 Cases with 8p Rearrangements Defines a Continuum of Fragility of the Region.

Improvements in microarray-based comparative genomic hybridization technology have allowed for high-resolution detection of genome wide copy number alterations, leading to a better definition of rearrangements and supporting the study of pathogenesis mechanisms. In this study, we focused our attention on chromosome 8p. We report 12 cases of 8p rearrangements, analyzed by molecular karyotype, evidencing a continuum of fragility that involves the entire short arm. The breakpoints seem more concentrated in three intervals: one at the telomeric end, the others at 8p23.1, close to the beta-defensin gene cluster and olfactory receptor low-copy repeats. Hypothetical mechanisms for all cases are described. Our data extend the cohort of published patients with 8p aberrations and highlight the need to pay special attention to these sequences due to the risk of formation of new chromosomal aberrations with pathological effects.

Human Chromosome 18 and Acrocentrics: A Dangerous Liaison.

The presence of thousands of repetitive sequences makes the centromere a fragile region subject to breakage. In this study we collected 31 cases of rearrangements of chromosome 18, of which 16 involved an acrocentric chromosome, during genetic screening done in three centers. We noticed a significant enrichment of reciprocal translocations between the centromere of chromosome 18 and the centromeric or pericentromeric regions of the acrocentrics. We describe five cases with translocation between chromosome 18 and an acrocentric chromosome, and one case involving the common telomere regions of chromosomes 18p and 22p. In addition, we bring evidence to support the hypothesis that chromosome 18 preferentially recombines with acrocentrics: (i) the presence on 18p11.21 of segmental duplications highly homologous to acrocentrics, that can justify a NAHR mechanism; (ii) the observation by 2D-FISH of the behavior of the centromeric regions of 18 respect to the centromeric regions of acrocentrics in the nuclei of normal subjects; (iii) the contact analysis among these regions on published Hi-C data from the human lymphoblastoid cell line (GM12878).

Genomic and Epigenomic Profile of Uterine Smooth Muscle Tumors of Uncertain Malignant Potential (STUMPs) Revealed Similarities and Differences with Leiomyomas and Leiomyosarcomas.

Uterine smooth muscle tumors of uncertain malignant potential (STUMPs) represent a heterogeneous group of tumors that cannot be histologically diagnosed as unequivocally benign or malignant. For this reason, many authors are working to obtain a better definition of diagnostic and prognostic criteria. In this work, we analyzed the genomic and epigenomic profile of uterine smooth muscle tumors (USMTs) in order to find similarities and differences between STUMPs, leiomyosarcomas (LMSs) and leiomyomas (LMs), and possibly identify prognostic factors in this group of tumors. Array-CGH data on 23 USMTs demonstrated the presence of a more similar genomic profile between STUMPs and LMSs. Some genes, such as PRKDC and PUM2, with a potential prognostic value, were never previously associated with STUMP. The methylation data appears to be very promising, especially with regards to the divergent profile found in the sample that relapsed, characterized by an overall CGI hypomethylation. Finally, the Gene Ontology analysis highlighted some cancer genes that could play a pivotal role in the unexpected aggressive behavior that can be found in some of these tumors. These genes could prove to be prognostic markers in the future.

Spontaneous chromosomal instability in peripheral blood lymphocytes from two molecularly confirmed Italian patients with Hereditary Fibrosis Poikiloderma: insights into cancer predisposition.

Two Italian patients with the initial clinical diagnosis of Rothmund-Thomson syndrome were negative for RECQL4 mutations but showed in peripheral blood cells a spontaneous chromosomal instability significantly higher than controls. Revisiting after time their clinical phenotype, the suggestive matching with the autosomal dominant syndrome Poikiloderma, Hereditary Fibrosing with Tendon Contracture, Myopathy and Pulmonary fibrosis (POIKTMP) was confirmed by identification of the c.1879A>G (p.Arg627Gly) alteration in FAM111B. We compare the overall clinical signs of our patients with those of reported carriers of the same mutation and present the up-to-date mutational repertoire of FAM111B and the related phenotypic spectrum. Our snapshot highlights the age-dependent clinical expressivity of POIKTMP and the need to follow-up patients to monitor the multi-tissue impairment caused by FAM111B alterations. We link our chromosomal instability data to the role of FAM111B in cancer predisposition, pointed out by its implication in DNA-repair pathways and the outcome of pancreatic cancer in 2 out of 17 adult POIKTMP patients. The chromosomal instability herein highlighted well connects POIKTMP to cancer-predisposing syndromes, such as Rothmund-Thomson which represents the first hereditary poikiloderma entering in differential diagnosis with POIKTMP.

Instability of Short Arm of Acrocentric Chromosomes: Lesson from Non-Acrocentric Satellited Chromosomes. Report of 24 Unrelated Cases.

Satellited non-acrocentric autosomal chromosomes (ps-qs-chromosomes) are the result of an interchange between sub- or telomeric regions of autosomes and the p arm of acrocentrics. The sequence homology at the rearrangement breakpoints appears to be, among others, the most frequent mechanism generating these variant chromosomes. The unbalanced carriers of this type of translocation may or may not display phenotypic abnormalities. With the aim to understand the causative mechanism, we revised all the ps-qs-chromosomes identified in five medical genetics laboratories, which used the same procedures for karyotype analysis, reporting 24 unrelated cases involving eight chromosomes. In conclusion, we observed three different scenarios: true translocation, benign variant and complex rearrangement. The detection of translocation partners is essential to evaluate possible euchromatic unbalances and to infer their effect on phenotype. Moreover, we emphasize the importance to perform both, molecular and conventional cytogenetics methods, to better understand the behavior of our genome.

Refining the Phenotype of Recurrent Rearrangements of Chromosome 16.

Chromosome 16 is one of the most gene-rich chromosomes of our genome, and 10% of its sequence consists of segmental duplications, which give instability and predisposition to rearrangement by the recurrent mechanism of non-allelic homologous recombination. Microarray technologies have allowed for the analysis of copy number variations (CNVs) that can contribute to the risk of developing complex diseases. By array comparative genomic hybridization (CGH) screening of 1476 patients, we detected 27 cases with CNVs on chromosome 16. We identified four smallest regions of overlapping (SROs): one at 16p13.11 was found in seven patients; one at 16p12.2 was found in four patients; two close SROs at 16p11.2 were found in twelve patients; finally, six patients were found with atypical rearrangements. Although phenotypic variability was observed, we identified a male bias for Childhood Apraxia of Speech associated to 16p11.2 microdeletions. We also reported an elevated frequency of second-site genomic alterations, supporting the model of the second hit to explain the clinical variability associated with CNV syndromes. Our goal was to contribute to the building of a chromosome 16 disease-map based on disease susceptibility regions. The role of the CNVs of chromosome 16 was increasingly made clear in the determination of developmental delay. We also found that in some cases a second-site CNV could explain the phenotypic heterogeneity by a simple additive effect or a pejorative synergistic effect.

FANCM c.5791C>T nonsense mutation (rs144567652) induces exon skipping, affects DNA repair activity and is a familial breast cancer risk factor.

Numerous genetic factors that influence breast cancer risk are known. However, approximately two-thirds of the overall familial risk remain unexplained. To determine whether some of the missing heritability is due to rare variants conferring high to moderate risk, we tested for an association between the c.5791C>T nonsense mutation (p.Arg1931*; rs144567652) in exon 22 of FANCM gene and breast cancer. An analysis of genotyping data from 8635 familial breast cancer cases and 6625 controls from different countries yielded an association between the c.5791C>T mutation and breast cancer risk [odds ratio (OR) = 3.93 (95% confidence interval (CI) = 1.28-12.11; P = 0.017)]. Moreover, we performed two meta-analyses of studies from countries with carriers in both cases and controls and of all available data. These analyses showed breast cancer associations with OR = 3.67 (95% CI = 1.04-12.87; P = 0.043) and OR = 3.33 (95% CI = 1.09-13.62; P = 0.032), respectively. Based on information theory-based prediction, we established that the mutation caused an out-of-frame deletion of exon 22, due to the creation of a binding site for the pre-mRNA processing protein hnRNP A1. Furthermore, genetic complementation analyses showed that the mutation influenced the DNA repair activity of the FANCM protein. In summary, we provide evidence for the first time showing that the common p.Arg1931* loss-of-function variant in FANCM is a risk factor for familial breast cancer.

Solid cell nests of the thyroid gland: morphological, immunohistochemical and genetic features.

AIMS: The correct identification of solid cell nests (SCNs) is an important issue in thyroid pathology because of the spectrum of differential diagnoses of this type of lesion. METHODS AND RESULTS: Ten cases of 295 consecutive thyroidectomies showed the presence of SCNs at histological examination. The identification of the exact SCN type required the distinction of the cystic and solid pattern; SCNs were usually composed of a mixture of main cells (MCs) and C-cells (CCs). The immunohistochemical calcitonin stain identified CCs easily, both inside SCNs and dispersed in islets at the periphery. For the characterization of MCs, we added the utility of p40 to p63. The use of thyroid transcription factor-1 (TTF-1) helped in their identification, as MCs did not react with this marker; the combination of TTF-1 and p40 or p63 IHC stains was useful for the characterization of cystic SCNs of both types 3 and 4. The negativity of mouse monoclonal mesothelioma antibody (HMBE-1) and a very low proliferative index (MIB-1) supported the diagnosis. [Correction added on 23 November 2015, after online publication: MIB-1 was incorrectly defined, the expanded form was deleted.] We discourage the use of galectin-3 (Gal-3) and cytokeratin-19 (CK-19), as they have an important overlap with papillary thyroid carcinoma. The complete absence of any B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutations is an additional fundamental finding. CONCLUSIONS: We reviewed the most relevant morphological and immunohistochemical features of SCNs and have provided a genetic analysis of the BRAF gene because of its expanding use in thyroid pathology.

Proteome analysis in thyroid pathology.

The incidence of thyroid cancer has continuously increased due to its detection in the preclinical stage. Clinical research in thyroid pathology is focusing on the development of new diagnostic tools to improve the stratification of nodules that have biological, practical and economic consequences on the management of patients. Several clinical questions related to thyroid carcinoma remain open and the use of proteomic research in the hunt for new targets with potential diagnostic applications has an important role in the solutions. Many different proteomic approaches are used to investigate thyroid lesions, including mass spectrometry profiling and imaging technologies. These approaches have been applied to different human tissues (cytological specimens, frozen sections, formalin-fixed paraffin embedded tissue or Tissue Micro Arrays). Moreover, other specimens are used for biomarker discovery, such as cell lines and the secretome. Alternative approaches, such as metabolomics and lipidomics, are also used and integrated within proteomics.

Cytogenetically Balanced Reciprocal Translocation Could Hide Molecular Genomic Unbalances: Implications for Foetal Phenotype Correlation.

When an increased nuchal translucency (>3.00 mm) is observed during the echographic examination of a foetus in the first trimester of pregnancy, an increased risk of chromosomopathy is considered, and the pregnant woman is offered the possibility of an invasive investigation. Here, we focused our attention on prenatal diagnosis issues in cases of foetuses with cytogenetically balanced reciprocal translocations. We report the finding of a cytogenetically balanced, de facto genomically unbalanced translocation that poses a challenge in a case of prenatal diagnosis, changing the risk of Down syndrome in a Zellweger syndromic spectrum risk (PEX3 deletion). At term, a healthy baby was born. This case teaches that prenatal diagnosis in cases of foetuses at increased risk of chromosomal abnormality imperatively requires molecular investigation in addition to a morphological karyotype.

Olfactory receptor genes and chromosome 11 structural aberrations: Players or spectators?

The largest multi-gene family in metazoans is the family of olfactory receptor (OR) genes. Human ORs are organized in clusters over most chromosomes and seem to include >0.1% the human genome. Because 369 out of 856 OR genes are mapped on chromosome 11 (HSA11), we sought to determine whether they mediate structural rearrangements involving this chromosome. To this aim, we analyzed 220 specimens collected during diagnostic procedures involving structural rearrangements of chromosome 11. A total of 222 chromosomal abnormalities were included, consisting of inversions, deletions, translocations, duplications, and one insertion, detected by conventional chromosome analysis and/or fluorescence in situ hybridization (FISH) and array comparative genomic hybridization (array-CGH). We verified by bioinformatics and statistical approaches the occurrence of breakpoints in cytobands with or without OR genes. We found that OR genes are not involved in chromosome 11 reciprocal translocations, suggesting that different DNA motifs and mechanisms based on homology or non-homology recombination can cause chromosome 11 structural alterations. We also considered the proximity between the chromosomal territories of chromosome 11 and its partner chromosomes involved in the translocations by using the deposited Hi-C data concerning the possible occurrence of chromosome interactions. Interestingly, most of the breakpoints are located in regions highly involved in chromosome interactions. Further studies should be carried out to confirm the potential role of chromosome territories' proximity in promoting genome structural variation, so fundamental in our understanding of the molecular basis of medical genetics and evolutionary genetics.

Targeted next-generation sequencing appoints c16orf57 as clericuzio-type poikiloderma with neutropenia gene.

Next-generation sequencing is a straightforward tool for the identification of disease genes in extended genomic regions. Autozygosity mapping was performed on a five-generation inbred Italian family with three siblings affected with Clericuzio-type poikiloderma with neutropenia (PN [MIM %604173]), a rare autosomal-recessive genodermatosis characterised by poikiloderma, pachyonychia, and chronic neutropenia. The siblings were initially diagnosed as affected with Rothmund-Thomson syndrome (RTS [MIM #268400]), with which PN shows phenotypic overlap. Linkage analysis on all living subjects of the family identified a large 16q region inherited identically by descent (IBD) in all affected family members. Deep sequencing of this 3.4 Mb region previously enriched with array capture revealed a homozygous c.504-2 A>C mismatch in all affected siblings. The mutation destroys the invariant AG acceptor site of intron 4 of the evolutionarily conserved C16orf57 gene. Two distinct deleterious mutations (c.502A>G and c.666_676+1del12) identified in an unrelated PN patient confirmed that the C16orf57 gene is responsible for PN. The function of the predicted C16orf57 gene is unknown, but its product has been shown to be interconnected to RECQL4 protein via SMAD4 proteins. The unravelled clinical and genetic identity of PN allows patients to undergo genetic testing and follow-up.

Genomic Complexity and Complex Chromosomal Rearrangements in Genetic Diagnosis: Two Illustrative Cases on Chromosome 7.

Complex chromosomal rearrangements are rare events compatible with survival, consisting of an imbalance and/or position effect of one or more genes, that contribute to a range of clinical presentations. The investigation and diagnosis of these cases are often difficult. The interpretation of the pattern of pairing and segregation of these chromosomes during meiosis is important for the assessment of the risk and the type of imbalance in the offspring. Here, we investigated two unrelated pediatric carriers of complex rearrangements of chromosome 7. The first case was a 2-year-old girl with a severe phenotype. Conventional cytogenetics evidenced a duplication of part of the short arm of chromosome 7. By array-CGH analysis, we found a complex rearrangement with three discontinuous trisomy regions (7p22.1p21.3, 7p21.3, and 7p21.3p15.3). The second case was a newborn investigated for hypodevelopment and dimorphisms. The karyotype analysis promptly revealed a structurally altered chromosome 7. The array-CGH analysis identified an even more complex rearrangement consisting of a trisomic region at 7q11.23q22 and a tetrasomic region of 4.5 Mb spanning 7q21.3 to q22.1. The mother's karyotype examination revealed a complex rearrangement of chromosome 7: the 7q11.23q22 region was inserted in the short arm at 7p15.3. Finally, array-CGH analysis showed a trisomic region that corresponds to the tetrasomic region of the son. Our work proved that the integration of several technical solutions is often required to appropriately analyze complex chromosomal rearrangements in order to understand their implications and offer appropriate genetic counseling.

Evaluation of family history in individuals with heterozygous BRCA pathogenic variants diagnosed with breast or ovarian cancer in a single center in Italy.

BACKGROUND: BRCA1 and BRCA2 gene mutations are responsible for 5% of breast cancer (BC) and 10-15% of ovarian cancer (EOC). The presence of a germline mutation and therefore the identification of subjects at high risk of developing cancer should ideally precede the onset of the disease, so that appropriate surveillance and risk-reducing treatments can be proposed. In this study, we revisited the family history (FH) of women who tested positive for BRCA mutations after being diagnosed with BC or EOC. METHODS: The National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology (NCCN Guidelines®), and the Italian Association of Medical Oncology (AIOM) guidelines were applied to the FH of 157 women who were referred to San Gerardo Hospital for genetic counseling. RESULTS: Almost 85% of women had an FH of BRCA-related cancer. 63.7% and 52.2% of women could have undergone genetic testing according to NCCN and AIOM testing criteria (p < .05) before tumor diagnosis. An FH of EOC was the most frequent NCCN criterion, followed by BC diagnosed <45 years old. Sixty-five percent of deceased women could have undergone genetic testing before developing cancer. CONCLUSIONS: FH is a powerful tool to identify high-risk individuals eligible for genetic counseling and testing. Testing of healthy individuals should be considered when an appropriately affected family member is unavailable for testing.

Exploring the link between MORF4L1 and risk of breast cancer.

INTRODUCTION: Proteins encoded by Fanconi anemia (FA) and/or breast cancer (BrCa) susceptibility genes cooperate in a common DNA damage repair signaling pathway. To gain deeper insight into this pathway and its influence on cancer risk, we searched for novel components through protein physical interaction screens. METHODS: Protein physical interactions were screened using the yeast two-hybrid system. Co-affinity purifications and endogenous co-immunoprecipitation assays were performed to corroborate interactions. Biochemical and functional assays in human, mouse and Caenorhabditis elegans models were carried out to characterize pathway components. Thirteen FANCD2-monoubiquitinylation-positive FA cell lines excluded for genetic defects in the downstream pathway components and 300 familial BrCa patients negative for BRCA1/2 mutations were analyzed for genetic mutations. Common genetic variants were genotyped in 9,573 BRCA1/2 mutation carriers for associations with BrCa risk. RESULTS: A previously identified co-purifying protein with PALB2 was identified, MRG15 (MORF4L1 gene). Results in human, mouse and C. elegans models delineate molecular and functional relationships with BRCA2, PALB2, RAD51 and RPA1 that suggest a role for MRG15 in the repair of DNA double-strand breaks. Mrg15-deficient murine embryonic fibroblasts showed moderate sensitivity to γ-irradiation relative to controls and reduced formation of Rad51 nuclear foci. Examination of mutants of MRG15 and BRCA2 C. elegans orthologs revealed phenocopy by accumulation of RPA-1 (human RPA1) nuclear foci and aberrant chromosomal compactions in meiotic cells. However, no alterations or mutations were identified for MRG15/MORF4L1 in unclassified FA patients and BrCa familial cases. Finally, no significant associations between common MORF4L1 variants and BrCa risk for BRCA1 or BRCA2 mutation carriers were identified: rs7164529, Ptrend = 0.45 and 0.05, P2df = 0.51 and 0.14, respectively; and rs10519219, Ptrend = 0.92 and 0.72, P2df = 0.76 and 0.07, respectively. CONCLUSIONS: While the present study expands on the role of MRG15 in the control of genomic stability, weak associations cannot be ruled out for potential low-penetrance variants at MORF4L1 and BrCa risk among BRCA2 mutation carriers.

Two new CHEK2 germ-line variants detected in breast cancer/sarcoma families negative for BRCA1, BRCA2, and TP53 gene mutations.

CHEK2 gene mutations occur in a subset of patients with familial breast cancer, acting as moderate/low penetrance cancer susceptibility alleles. Although CHEK2 is no longer recognized as a major determinant of the Li-Fraumeni syndrome, a hereditary condition predisposing to cancer at multiple sites, it cannot be ruled out that mutations of this gene play a role in malignancies arising in peculiar multi-cancer families. To assess the contribution of CHEK2 to the breast cancer/sarcoma phenotype, we screened for germ-line sequence variations of the gene among 12 probands from hereditary breast/ovarian cancer families with one case of sarcoma that tested wild-type for mutations in the BRCA1, BRCA2, and TP53 genes. Two cases harbored previously unreported mutations in CHEK2, the c.507delT and c.38A>G, leading to protein truncation (p.Phe169LeufsX2) and amino acid substitution (p.His13Arg), respectively. These mutations were not considered common polymorphic variants, as they were undetected in 230 healthy controls of the same ethnic origin. While the c.38A>G encodes a mutant protein that behaves in biochemical assays as the wild-type form, the c.507delT is a loss-of-function mutation. The identification of two previously unreported CHEK2 variants, including a truncating mutation leading to constitutional haploinsufficiency, in individuals belonging to families selected for breast cancer/sarcoma phenotype, supports the hypothesis that the CHEK2 gene may act as a factor contributing to individual tumor development in peculiar familial backgrounds.

The CASP8 rs3834129 polymorphism and breast cancer risk in BRCA1 mutation carriers.

The rs3834129 polymorphism, in the promoter of CASP8 gene, has been recently reported as associated with breast cancer risk in the general population, with the minor allele del having a protective effect. Some of the genetic variants found associated with breast cancer risk were reported as risk modifiers in individuals with mutations in BRCA1 and BRCA2 genes. Here, we tested the effect of the rs3834129 del allele on breast cancer risk in BRCA mutation carriers. The rs3834129 was genotyped in a total of 1,207 Italian female BRCA mutation carriers. Of these, 740 carried a BRCA1 mutation and 467 a BRCA2 mutation. Overall, 699 were affected with breast cancer and 508 were unaffected. When considering class 1 (loss-of-function) BRCA mutations, hazard ratios estimated by weighted multivariable Cox regression model, for individuals with at least one copy of the del allele, were 1.46 (95% confidence interval (CI): 1.08-1.99) for BRCA1 and BRCA2 mutation carriers combined, 1.74 (95% CI: 1.24-2.46) for BRCA1 mutation carriers, and 1.09 (95% CI: 0.66-1.80) for BRCA2 mutation carriers. These results suggest that the minor allele del of rs3834129 is associated under a dominant model with increased breast cancer risk in carriers of BRCA1 mutations but not in carriers of BRCA2 mutations.

Evidence for a link between TNFRSF11A and risk of breast cancer.

Intracellular signaling mediated by the receptor activator of nuclear factor-κB [Rank, encoded by the tumor necrosis factor receptor superfamily, member 11a (Tnfrsf11a) gene] is fundamental for mammary gland development in mice, regulating the expansion of stem and progenitor cell compartments. Conversely, Rank overexpression in mice promotes abnormal proliferation and impairs differentiation, leading to an increased incidence of tumorigenesis. Here, we show that a common genetic variant near the 5'-end of TNFRSF11A, rs7226991, is associated with breast cancer risk in the general population and among carriers of mutations in the breast cancer 2, early onset (BRCA2) gene. Akin to the results of the Cancer and Genetics Markers of Susceptibility initiative, combined analysis of rs7226991 in two Spanish case-control studies (1,365 controls and 1,323 cases in total) revealed a significant association with risk: odds ratio (OR) = 0.88, 95% confidence interval (CI) 0.78-0.98, P (trend) = 0.025. Subsequent examination of BRCA1 (n = 1,017) and BRCA2 (n = 885) mutation carriers revealed a consistent association in the latter group: weighted hazard ratio ((w)HR) = 0.70; 95% CI 0.55-0.88; and P (trend) = 0.003; compared to BRCA1 mutation carriers, (w)HR = 0.91; 95% CI 0.76-1.10; and P (trend) = 0.33. The results of this study need to be replicated in other populations and with larger numbers of BRCA1/2 mutation carriers.