CTNND1 is involved in germline predisposition to early-onset gastric cancer by affecting cell-to-cell interactions.

BACKGROUND: CDH1 and CTNNA1 remain as the main genes for hereditary gastric cancer. However, they only explain a small fraction of gastric cancer cases with suspected inherited basis. In this study, we aimed to identify new hereditary genes for early-onset gastric cancer patients (EOGC; < 50 years old). METHODS: After germline exome sequencing in 20 EOGC patients and replication of relevant findings by gene-panel sequencing in an independent cohort of 152 patients, CTNND1 stood out as an interesting candidate gene, since its protein product (p120ctn) directly interacts with E-cadherin. We proceeded with functional characterization by generating two knockout CTNND1 cellular models by gene editing and introducing the detected genetic variants using a lentiviral delivery system. We assessed ß-catenin and E-cadherin levels, cell detachment, as well as E-cadherin localization and cell-to-cell interaction by spheroid modeling. RESULTS: Three CTNND1 germline variants [c.28_29delinsCT, p.(Ala10Leu); c.1105C > T, p.(Pro369Ser); c.1537A > G, p.(Asn513Asp)] were identified in our EOGC cohorts. Cells encoding CTNND1 variants displayed altered E-cadherin levels and intercellular interactions. In addition, the p.(Pro369Ser) variant, located in a key region in the E-cadherin/p120ctn binding domain, showed E-cadherin mislocalization. CONCLUSIONS: Defects in CTNND1 could be involved in germline predisposition to gastric cancer by altering E-cadherin and, consequently, cell-to-cell interactions. In the present study, CTNND1 germline variants explained 2% (3/172) of the cases, although further studies in larger external cohorts are needed.

Quality of Colonoscopy Is Associated With Adenoma Detection and Postcolonoscopy Colorectal Cancer Prevention in Lynch Syndrome.

BACKGROUND & AIMS: Colonoscopy reduces colorectal cancer (CRC) incidence and mortality in Lynch syndrome (LS) carriers. However, a high incidence of postcolonoscopy CRC (PCCRC) has been reported. Colonoscopy is highly dependent on endoscopist skill and is subject to quality variability. We aimed to evaluate the impact of key colonoscopy quality indicators on adenoma detection and prevention of PCCRC in LS. METHODS: We conducted a multicenter study focused on LS carriers without previous CRC undergoing colonoscopy surveillance (n = 893). Incident colorectal neoplasia during surveillance and quality indicators of all colonoscopies were analyzed. We performed an emulated target trial comparing the results from the first and second surveillance colonoscopies to assess the effect of colonoscopy quality indicators on adenoma detection and PCCRC incidence. Risk analyses were conducted using a multivariable logistic regression model. RESULTS: The 10-year cumulative incidence of adenoma and PCCRC was 60.6% (95% CI, 55.5%-65.2%) and 7.9% (95% CI, 5.2%-10.6%), respectively. Adequate bowel preparation (odds ratio [OR], 2.07; 95% CI, 1.06-4.3), complete colonoscopies (20% vs 0%; P = .01), and pan-chromoendoscopy use (OR, 2.14; 95% CI, 1.15-3.95) were associated with significant improvement in adenoma detection. PCCRC risk was significantly lower when colonoscopies were performed during a time interval of less than every 3 years (OR, 0.35; 95% CI, 0.14-0.97). We observed a consistent but not significant reduction in PCCRC risk for a previous complete examination (OR, 0.16; 95% CI, 0.03-1.28), adequate bowel preparation (OR, 0.64; 95% CI, 0.17-3.24), or previous use of high-definition colonoscopy (OR, 0.37; 95% CI, 0.02-2.33). CONCLUSIONS: Complete colonoscopies with adequate bowel preparation and chromoendoscopy use are associated with improved adenoma detection, while surveillance intervals of less than 3 years are associated with a reduction of PCCRC incidence. In LS, high-quality colonoscopy surveillance is of utmost importance for CRC prevention.

Clinical and Pathological Characterization of Lynch-Like Syndrome.

BACKGROUND & AIMS: Lynch syndrome is characterized by DNA mismatch repair (MMR) deficiency. Some patients with suspected Lynch syndrome have DNA MMR deficiencies but no detectable mutations in genes that encode MMR proteins-this is called Lynch-like syndrome (LLS). There is no consensus on management of patients with LLS. We collected data from a large series of patients with LLS to identify clinical and pathology features. METHODS: We collected data from a nationwide-registry of patients with colorectal cancer (CRC) in Spain. We identified patients whose colorectal tumors had loss of MSH2, MSH6, PMS2, or MLH1 (based on immunohistochemistry), without the mutation encoding V600E in BRAF (detected by real-time PCR), and/or no methylation at MLH1 (determined by methylation-specific multiplex ligation-dependent probe amplification), and no pathogenic mutations in MMR genes, BRAF, or EPCAM (determined by DNA sequencing). These patients were considered to have LLS. We collected data on demographic, clinical, and pathology features and family history of neoplasms. The χ2 test was used to analyze the association between qualitative variables, followed by the Fisher exact test and the Student t test or the Mann-Whitney test for quantitative variables. RESULTS: We identified 160 patients with LLS; their mean age at diagnosis of CRC was 55 years and 66 patients were female (41%). The Amsterdam I and II criteria for Lynch syndrome were fulfilled by 11% of cases and the revised Bethesda guideline criteria by 65% of cases. Of the patients with LLS, 24% were identified in universal screening. There were no proportional differences in sex, indication for colonoscopy, immunohistochemistry, pathology findings, or personal history of CRC or other Lynch syndrome-related tumors between patients who met the Amsterdam and/or Bethesda criteria for Lynch syndrome and patients identified in universal screening for Lynch syndrome, without a family history of CRC. CONCLUSIONS: Patients with LLS have homogeneous clinical, demographic, and pathology characteristics, regardless of family history of CRC.

Role of POLE and POLD1 in familial cancer.

PURPOSE: Germline pathogenic variants in the exonuclease domain (ED) of polymerases POLE and POLD1 predispose to adenomatous polyps, colorectal cancer (CRC), endometrial tumors, and other malignancies, and exhibit increased mutation rate and highly specific associated mutational signatures. The tumor spectrum and prevalence of POLE and POLD1 variants in hereditary cancer are evaluated in this study. METHODS: POLE and POLD1 were sequenced in 2813 unrelated probands referred for genetic counseling (2309 hereditary cancer patients subjected to a multigene panel, and 504 patients selected based on phenotypic characteristics). Cosegregation and case-control studies, yeast-based functional assays, and tumor mutational analyses were performed for variant interpretation. RESULTS: Twelve ED missense variants, 6 loss-of-function, and 23 outside-ED predicted-deleterious missense variants, all with population allele frequencies <1%, were identified. One ED variant (POLE p.Met294Arg) was classified as likely pathogenic, four as likely benign, and seven as variants of unknown significance. The most commonly associated tumor types were colorectal, endometrial and ovarian cancers. Loss-of-function and outside-ED variants are likely not pathogenic for this syndrome. CONCLUSIONS: Polymerase proofreading-associated syndrome constitutes 0.1-0.4% of familial cancer cases, reaching 0.3-0.7% when only CRC and polyposis are considered. ED variant interpretation is challenging and should include multiple pieces of evidence.

Analysis of Lynch Syndrome Mismatch Repair Genes in Women with Endometrial Cancer.

OBJECTIVE: Endometrial cancer is the second most frequent neoplasm in women with Lynch syndrome (LS). We sought to assess whether analyzing women with endometrial cancer would identify families with LS not identified with current clinical criteria. METHODS: We included women diagnosed with endometrial cancer younger than 50 years and also older if they had a family cancer history associated with LS. In blood samples obtained, we analyzed mutations in mismatch repair (MMR) genes, as well as protein expression by immunohistochemistry and microsatellite instability (MSI) in tumour tissue. RESULTS: A total of 103 patients were enrolled. We detected 14 pathogenic mutations and 4 genetic variants of unknown clinical significance in MMR genes. We found MSI in 41.66% of the women with a pathogenic mutation. In this group, 76.92% showed loss of at least one MMR protein. Women with mutations were younger at diagnosis, but all of them had a family history compatible with LS. CONCLUSIONS: Analysis of the MMR genes, in particular MSH6, seems to be appropriate in women with endometrial cancer and a family history of tumours associated with LS.

Mammographic density and breast cancer in women from high risk families.

INTRODUCTION: Mammographic density (MD) is one of the strongest determinants of sporadic breast cancer (BC). In this study, we compared MD in BRCA1/2 mutation carriers and non-carriers from BRCA1/2 mutation-positive families and investigated the association between MD and BC among BRCA1/2 mutation carriers per type of mutation and tumor subtype. METHODS: The study was carried out in 1039 female members of BRCA1 and BRCA2 mutation-positive families followed at 16 Spanish Genetic Counseling Units. Participants' density was scored retrospectively from available mammograms by a single blinded radiologist using a 5-category scale (<10 %, 10-25 %, 25-50 %, 50-75 %, >75 %). In BC cases, we selected mammograms taken prior to diagnosis or from the contralateral breast, whereas, in non-cases, the last screening mammogram was evaluated. MD distribution in carriers and non-carriers was compared using ordinal logistic models, and the association between MD and BC in BRCA1/2 mutation carriers was studied using logistic regression. Huber-White robust estimators of variance were used to take into account correlations between family members. A similar multinomial model was used to explore this association by BC subtype. RESULTS: We identified and scored mammograms from 341 BRCA1, 350 BRCA2 mutation carriers and 229 non-carriers. Compared to non-carriers, MD was significantly lower among BRCA2 mutation carriers (odds ratio (OR) =0.71; P-value=0.04), but not among BRCA1 carriers (OR=0.84; P-value=0.33). MD was associated with subsequent development BC (OR per category of MD=1.45; 95 % confidence interval=1.18-1.78, P-value<0.001), with no significant differences between BRCA1 and BRCA2 mutation carriers (P-value=0.48). Finally, no statistically significant differences were observed in the association of MD with specific BC subtypes. CONCLUSIONS: Our study, the largest to date on this issue, confirms that MD is an independent risk factor for all BC subtypes in either BRCA1 and BRCA2 mutation carriers, and should be considered a phenotype risk marker in this context.

Capillary electrophoresis analysis of conventional splicing assays: IARC analytical and clinical classification of 31 BRCA2 genetic variants.

Rare sequence variants in "high-risk" disease genes, often referred as unclassified variants (UVs), pose a serious challenge to genetic testing. However, UVs resulting in splicing alterations can be readily assessed by in vitro assays. Unfortunately, analytical and clinical interpretation of these assays is often challenging. Here, we explore this issue by conducting splicing assays in 31 BRCA2 genetic variants. All variants were assessed by RT-PCR followed by capillary electrophoresis and direct sequencing. If assays did not produce clear-cut outputs (Class-2 or Class-5 according to analytical International Agency for Research on Cancer guidelines), we performed qPCR and/or minigene assays. The latter were performed with a new splicing vector (pSAD) developed by authors of the present manuscript (patent #P201231427 CSIC). We have identified three clinically relevant Class-5 variants (c.682-2A>G, c.7617+1G>A, and c.8954-5A>G), and 27 analytical Class-2 variants (not inducing splicing alterations). In addition, we demonstrate that rs9534262 (c.7806-14T>C) is a BRCA2 splicing quantitative trait locus.

Open-Source Bioinformatic Pipeline to Improve PMS2 Genetic Testing Using Short-Read NGS Data.

The molecular diagnosis of mismatch repair-deficient cancer syndromes is hampered by difficulties in sequencing the PMS2 gene, mainly owing to the PMS2CL pseudogene. Next-generation sequencing short reads cannot be mapped unambiguously by standard pipelines, compromising variant calling accuracy. This study aimed to provide a refined bioinformatic pipeline for PMS2 mutational analysis and explore PMS2 germline pathogenic variant prevalence in an unselected hereditary cancer (HC) cohort. PMS2 mutational analysis was optimized using two cohorts: 192 unselected HC patients for assessing the allelic ratio of paralogous sequence variants, and 13 samples enriched with PMS2 (likely) pathogenic variants screened previously by long-range genomic DNA PCR amplification. Reads were forced to align with the PMS2 reference sequence, except those corresponding to exon 11, where only those intersecting gene-specific invariant positions were considered. Afterward, the refined pipeline's accuracy was validated in a cohort of 40 patients and used to screen 5619 HC patients. Compared with our routine diagnostic pipeline, the PMS2_vaR pipeline showed increased technical sensitivity (0.853 to 0.956) in the validation cohort, identifying all previously PMS2 pathogenic variants found by long-range genomic DNA PCR amplification. Fifteen HC cohort samples carried a pathogenic PMS2 variant (15 of 5619; 0.285%), doubling the estimated prevalence in the general population. The refined open-source approach improved PMS2 mutational analysis accuracy, allowing its inclusion in the routine next-generation sequencing pipeline streamlining PMS2 screening.

Prevalence of Homologous Recombination Deficiency Among Patients With Germline RAD51C/D Breast or Ovarian Cancer.

Importance: RAD51C and RAD51D are involved in DNA repair by homologous recombination. Germline pathogenic variants (PVs) in these genes are associated with an increased risk of ovarian and breast cancer. Understanding the homologous recombination deficiency (HRD) status of tumors from patients with germline PVs in RAD51C/D could guide therapeutic decision-making and improve survival. Objective: To characterize the clinical and tumor characteristics of germline RAD51C/D PV carriers, including the evaluation of HRD status. Design, Setting, and Participants: This retrospective cohort study included 91 index patients plus 90 relatives carrying germline RAD51C/D PV (n = 181) in Spanish hospitals from January 1, 2014, to December 31, 2021. Genomic and functional HRD biomarkers were assessed in untreated breast and ovarian tumor samples (n = 45) from June 2022 to February 2023. Main Outcomes and Measures: Clinical and pathologic characteristics were assessed using descriptive statistics. Genomic HRD by genomic instability scores, functional HRD by RAD51, and gene-specific loss of heterozygosity were analyzed. Associations between HRD status and tumor subtype, age at diagnosis, and gene-specific loss of heterozygosity in RAD51C/D were investigated using logistic regression or the t test. Results: A total of 9507 index patients were reviewed, and 91 patients (1.0%) were found to carry a PV in RAD51C/D; 90 family members with a germline PV in RAD51C/D were also included. A total of 157 of carriers (86.7%) were women and 181 (55.8%) had received a diagnosis of cancer, mainly breast cancer or ovarian cancer. The most prevalent PVs were c.1026+5_1026+7del (11 of 56 [19.6%]) and c.709C>T (9 of 56 [16.1%]) in RAD51C and c.694C>T (20 of 35 [57.1%]) in RAD51D. In untreated breast cancer and ovarian cancer, the prevalence of functional and genomic HRD was 55.2% (16 of 29) and 61.1% (11 of 18) for RAD51C, respectively, and 66.7% (6 of 9) and 90.0% (9 of 10) for RAD51D. The concordance between HRD biomarkers was 91%. Tumors with the same PV displayed contrasting HRD status, and age at diagnosis did not correlate with the occurrence of HRD. All breast cancers retaining the wild-type allele were estrogen receptor positive and lacked HRD. Conclusions and Relevance: In this cohort study of germline RAD51C/D breast cancer and ovarian cancer, less than 70% of tumors displayed functional HRD, and half of those that did not display HRD were explained by retention of the wild-type allele, which was more frequent among estrogen receptor-positive breast cancers. Understanding which tumors are associated with RAD51C/D and HRD is key to identify patients who can benefit from targeted therapies, such as PARP (poly [adenosine diphosphate-ribose] polymerase) inhibitors.

Impact of concurrent tumour events on the prostate cancer outcomes of germline BRCA2 mutation carriers.

BACKGROUND: Several studies have reported the association of germline BRCA2 (gBRCA2) mutations with poor clinical outcomes in prostate cancer (PCa), but the impact of concurrent somatic events on gBRCA2 carriers survival and disease progression is unknown. PATIENTS AND METHODS: To ascertain the role of frequent somatic genomic alterations and histology subtypes in the outcomes of gBRCA2 mutation carriers and non-carriers, we correlated the tumour characteristics and clinical outcomes of 73 gBRCA2 and 127 non-carriers. Fluorescent in-situ hybridisation and next-generation sequencing were used to detect copy number variations in BRCA2, RB1, MYC and PTEN. Presence of intraductal and cribriform subtypes was also assessed. The independent impact of these events on cause-specific survival (CSS), metastasis-free survival and time to castration-resistant disease was assessed using cox-regression models. RESULTS: Somatic BRCA2-RB1 co-deletion (41% versus 12%, p < 0.001) and MYC amplification (53.4% versus 18.8%, p < 0.001) were enriched in gBRCA2 compared to sporadic tumours. Median CSS from diagnosis of PCa was 9.1 versus 17.6 years in gBRCA2 carriers and non-carriers, respectively (HR 2.12; p = 0.002), Median CSS in gBRCA2 carriers increased to 11.3 and 13.4 years in the absence of BRCA2-RB1 deletion or MYC amplification, respectively. Median CSS of non-carriers decreased to 8 and 2.6 years if BRCA2-RB1 deletion or MYC amplification were detected. CONCLUSIONS: gBRCA2-related prostate tumours are enriched for aggressive genomic features, such as BRCA2-RB1 co-deletion and MYC amplification. The presence or absence of these events modify the outcomes of gBRCA2 carriers.

Genome-wide linkage scan reveals three putative breast-cancer-susceptibility loci.

Despite all the research efforts made during the last few decades, most of the cases of families with breast cancer remain unexplained. Mutations in BRCA1 and BRCA2, and in other breast-cancer-susceptibility genes, account for about 25% of familial breast cancer. Linkage studies have failed to identify other breast-cancer-susceptibility genes. The selection criteria of the families, differences in the population background, or clinical and genetic heterogeneity, among other factors, might determine the power to detect the linkage signal. We have performed a SNP-based linkage scan with a total of 6000 SNP markers across the genome in 41 breast-cancer Spanish families, with an average of four breast-cancer cases per family not associated with BRCA1 or BRCA2 germline mutations. In addition, we have included three BRCA-positive families to test the power in linkage detection from a low-complexity family in which a high-penetrance mutation segregates. We have identified three regions of interest, located on 3q25, 6q24, and 21q22. The two former regions showed a suggestive linkage signal (HLOD scores 3.01 and 2.26, respectively), and the latter region showed a significant linkage signal (HLOD score 3.55). Moreover, we found that a subset of 13 families with bilateral breast cancer presented a HLOD of 3.13 on the 3q25 region. Our results suggest that several variables must be taken into account before performing a linkage study in familial breast cancer because of the high heterogeneity within non-BRCA1/2 families. Phenotypic and geographic homogeneity could be the most important factors.

Transcriptional characteristics of familial non-BRCA1/BRCA2 breast tumors.

To better understand the alterations present in the group of the so-called BRCAX tumors, we have used a cDNA microarray containing genes related to tumorigenesis and analyzed a series of 49 tumors consisting of 13 BRCA1, 14 BRCAX and 22 sporadic. We have confirmed that the BRCAX tumors are heterogeneous and can be divided in at least two main subgroups, so-called A and B, transcriptionally distinguishable and with different altered pathways within each of the groups. We have found that BRCAX-A and B subgroups, can be classified as Luminal A and Luminal B, respectively, taking into account the intrinsic phenotypes defined for the sporadic breast tumors. We have found that, at the somatic level, the BRCAX-B tumors are identical to their sporadic Luminal B counterparts, whereas BRCAX-A, despite having a Luminal A phenotype, shows additional genomic alterations. We have found 21 deregulated genes in the BRCAX-A group that we have called "the BRCAX susceptibility pathway" and suggested it as a candidate to search for new genes involved in the inherited susceptibility underlying the disease in this group.

Paired Somatic-Germline Testing of 15 Polyposis and Colorectal Cancer-Predisposing Genes Highlights the Role of APC Mosaicism in de Novo Familial Adenomatous Polyposis.

Familial adenomatous polyposis (FAP) is an autosomal dominant syndrome responsible for 1% of colorectal cancers (CRCs). Up to 90% of classic FAPs are caused by inactivating mutations in APC, and mosaicism has been previously reported in 20% of de novo cases, usually linked to milder phenotypic manifestations. This study aimed to explore the prevalence of mosaicism in 11 unsolved cases of classic FAP and to evaluate the diagnostic yield of somatic testing. Paired samples of colorectal polyps, tumors, and/or mucosa were analyzed using a custom next-generation sequencing panel targeting 15 polyposis and CRC-predisposing genes. Whenever possible, the extension of mosaicism to blood or sperm was also examined. Of 11 patients with classic adenomatous polyposis, a mosaic pathogenic variant in APC was identified in 7 (64%). No other altered genes were identified. In two of seven patients (29%), mosaicism was found restricted to colonic tissues, whereas in five of seven patients (71%), it was extended to the blood. Germline affectation was confirmed in one patient. We report the first analysis at a somatic level of 15 genes associated with CRC susceptibility, which highlights the role of APC mosaicism in classic FAP etiology. The results further reinforce the importance of testing target tissues when blood test results are negative.

Identification of a new complex deleterious mutation in exon 18 of the BRCA2 gene in a hereditary male/female breast cancer family.

We report a novel complex mutation that consists of a deletion of 12 bp and an insertion of 2 bp (c.8402_8413del12ins2bp) in the exon 18 of the BRCA2 gene. This is a frameshift mutation that causes a disruption of the translational reading frame resulting in a stop codon downstream in the 2729 position of the BRCA2 protein. The mutation was present in a Spanish hereditary male/female breast cancer family.

Association of premenopausal risk-reducing salpingo-oophorectomy with breast cancer risk in BRCA1/2 mutation carriers: Maximising bias-reduction.

BACKGROUND: Whether risk-reducing salpingo-oophorectomy (RRSO) in BRCA1/2 carriers reduces the breast cancer (BC) risk is conflicting, potentially due to methodological issues of prior analysis. We analysed the association between premenopausal RRSO and BC risk in BRCA1/2 carriers after adjusting for potential biases. METHODS: We analysed data from 444 BRCA1 and 409 BRCA2 carriers under age 51 with no cancer prior to genetic testing or during first 6 months of surveillance (to avoid cancer-induced testing bias and prevalent-cancer bias). Observation started 6 months after genetic testing (to avoid event-free time bias), until BC diagnosis, risk-reducing mastectomy (RRM) or death. A multistate model with four states (non-RRSO, RRSO, RRM and BC) and five transitions was fitted to characterise outcomes and to calculate the BC risk reduction after premenopausal RRSO (before age 51). A systematic review was performed to assess the association between premenopausal RRSO and BC. RESULTS: During a mean follow-up of 4.3 years, 96 women (11.3%) developed BC (54 BRCA1, 42 BRCA2). The risk of BC after premenopausal RRSO decreased significantly in BRCA1 carriers (hazard ratio (HR) = 0.45 [95% confidence interval (CI):0.22-0.92]), but was not conclusive in BRCA2 carriers (HR = 0.77 [95%CI:0.35-1.67]). The systematic review suggested that premenopausal RRSO is associated with a decrease of BC risk in both BRCA1 and BRCA2 carriers. CONCLUSIONS: Premenopausal RRSO was associated with BC risk reduction in BRCA1 carriers, which can help guide cancer risk-reducing strategies in this population. Longer follow-up and larger sample size may be needed to estimate the potential benefit in BRCA2 carriers.

Complete Loss of EPCAM Immunoexpression Identifies EPCAM Deletion Carriers in MSH2-Negative Colorectal Neoplasia.

The use of epithelial cell adhesion molecule (EPCAM) immunohistochemistry (IHC) is not included in the colorectal cancer (CRC) screening algorithm to detect Lynch syndrome (LS) patients. The aim of the present study was to demonstrate that EPCAM IHC is a useful tool to guide the LS germ-line analysis when a loss of MSH2 expression was present. We retrospectively studied MSH2 and EPCAM IHC in a large series of 190 lesions composed of malignant neoplasms (102), precursor lesions of gastrointestinal (71) and extra-gastrointestinal origin (9), and benign neoplasms (8) from different organs of 71 patients suspicious of being LS due to MSH2 alterations. LS was confirmed in 68 patients, 53 with MSH2 mutations and 15 with EPCAM 3'-end deletions. Tissue microarrays were constructed with human normal tissues and their malignant counterparts to assist in the evaluation of EPCAM staining. Among 154 MSH2-negative lesions, 17 were EPCAM-negative, including 10 CRC and 7 colorectal polyps, and 5 of them showed only isolated negative glands. All lesions showing a lack of EPCAM expression belonged to patients with EPCAM 3'-end deletions. EPCAM IHC is a useful screening tool, with 100% specificity to identify LS patients due to EPCAM 3'-end deletions in MSH2-negative CRC and MSH2-negative colorectal polyps.

Risk of Cancer in Family Members of Patients with Lynch-Like Syndrome.

Lynch syndrome (LS) is a common cause of hereditary colorectal cancer (CRC). Some CRC patients develop mismatch repair deficiency without germline pathogenic mutation, known as Lynch-like syndrome (LLS). We compared the risk of CRC in first-degree relatives (FDRs) in LLS and LS patients. LLS was diagnosed when tumors showed immunohistochemical loss of MSH2, MSH6, and PMS2; or loss of MLH1 with BRAF wild type; and/or no MLH1 methylation and absence of pathogenic mutation in these genes. CRC and other LS-related neoplasms were followed in patients diagnosed with LS and LLS and among their FDRs. Standardized incidence ratios (SIRs) were calculated for CRC and other neoplasms associated with LS among FDRs of LS and LLS patients. In total, 205 LS (1205 FDRs) and 131 LLS families (698 FDRs) had complete pedigrees. FDRs of patients with LLS had a high incidence of CRC (SIR, 2.08; 95% confidence interval (CI), 1.56-2.71), which was significantly lower than that in FDRs of patients with LS (SIR, 4.25; 95% CI, 3.67-4.90; p < 0.001). The risk of developing other neoplasms associated with LS also increased among FDR of LLS patients (SIR, 2.04; 95% CI, 1.44-2.80) but was lower than that among FDR of patients with LS (SIR, 5.01, 95% CI, 4.26-5.84; p < 0.001). FDRs with LLS have an increased risk of developing CRC as well as LS-related neoplasms, although this risk is lower than that of families with LS. Thus, their management should take into account this increased risk.

Hereditary Leiomyomatosis and Renal Cell Cancer Syndrome in Spain: Clinical and Genetic Characterization.

Hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) is a very rare hereditary disorder characterized by cutaneous leiomyomas (CLMs), uterine leiomyomas (ULMs), renal cysts (RCys) and renal cell cancers (RCCs). We aimed to describe the genetics, clinical features and potential genotype-phenotype associations in the largest cohort of fumarate hydratase enzyme mutation carriers known from Spain using a multicentre, retrospective study of individuals with a genetic or clinical diagnosis of HLRCC. We collected clinical information from medical records, analysed genetic variants and looked for genotype-phenotype associations. Analyses were performed using R 3.6.0. software. We included 197 individuals: 74 index cases and 123 relatives. CLMs were diagnosed in 65% of patients, ULMs in 90% of women, RCys in 37% and RCC in 10.9%. Twenty-seven different pathogenic variants were detected, 12 (44%) of them not reported previously. Patients with missense pathogenic variants showed higher frequencies of CLMs, ULMs and RCys, than those with loss-of-function variants (p = 0.0380, p = 0.0015 and p = 0.024, respectively). This is the first report of patients with HLRCC from Spain. The frequency of RCCs was lower than those reported in the previously published series. Individuals with missense pathogenic variants had higher frequencies of CLMs, ULMs and RCys.

Analysis of FANCB and FANCN/PALB2 fanconi anemia genes in BRCA1/2-negative Spanish breast cancer families.

Recent reports have shown that mutations in the FANCJ/BRIP1 and FANCN/PALB2 Fanconi Anemia (FA) genes confer a moderate breast cancer risk. Discussion has been raised on the phenotypic characteristics of the PALB2-associated families and tumors. The role of FANCB in breast cancer susceptibility has not been tested to date. Likewise PALB2 mutation frequency has not been studied in Spanish population. We analyzed the complete coding sequence and splicing sites of FANCB and PALB2 in 95 index cases of BRCA1/2-negative Spanish breast cancer families. We also performed an exhaustive screening of three previously described rare but recurrent PALB2 mutations in 725 additional probands. Pathogenic changes were not detected in FANCB. We found a novel PALB2 truncating mutation c.1056_1057delGA (p.K353IfsX7) in one of the 95 screened patients, accounting for a mutation frequency of 1% in our series. Further comprehensive screening of the novel mutation and of previously reported rare but recurrent PALB2 mutations did not reveal any carrier patient. We report the first example of LOH occurring in a PALB2-associated tumor. Our results rule out a major contribution of FANCB to hereditary breast cancer. Our data are consistent with the notion of individually rare PALB2 mutations, lack of mutational hot-spots in the gene and existence of between-population disease-allele heterogeneity. We show evidence that PALB2 loss of function might also conform to the inactivation model of a classic tumor-suppressor gene and present data that adds to the clinically relevant discussion about the existence of a PALB2-breast cancer phenotype.

The average cumulative risks of breast and ovarian cancer for carriers of mutations in BRCA1 and BRCA2 attending genetic counseling units in Spain.

PURPOSE: It is not clear that the published estimates of the breast and ovarian cancer penetrances of mutations in BRCA1 and BRCA2 can be used in genetic counseling in countries such as Spain, where the incidence of breast cancer in the general population is considerably lower, the prevalence of BRCA2 mutations seems to be higher, and a distinct spectrum of recurrent mutations exists for both genes. We aimed to estimate these penetrances for women attending genetic counseling units in Spain. EXPERIMENTAL DESIGN: We collected phenotype and genotype data on 155 BRCA1 and 164 BRCA2 mutation carrier families from 12 centers across the country. Average age-specific cumulative risks of breast cancer and ovarian cancer were estimated using a modified segregation analysis method. RESULTS: The estimated average cumulative risk of breast cancer to age 70 years was estimated to be 52% [95% confidence interval (95% CI), 26-69%] for BRCA1 mutation carriers and 47% (95% CI, 29-60%) for BRCA2 mutation carriers. The corresponding estimates for ovarian cancer were 22% (95% CI, 0-40%) and 18% (95% CI, 0-35%), respectively. There was some evidence (two-sided P = 0.09) that 330A>G (R71G) in BRCA1 may have lower breast cancer penetrance. CONCLUSIONS: These results are consistent with those from a recent meta-analysis of practically all previous penetrance studies, suggesting that women with BRCA1 and BRCA2 mutations attending genetic counseling services in Spain have similar risks of breast and ovarian cancer to those published for other Caucasian populations. Carriers should be fully informed of their mutation- and age-specific risks to make appropriate decisions regarding prophylactic interventions such as oophorectomy.