Eckloff, Bruce W.

Background: The primary role of natriuretic peptide receptor 3 (NPR3) is clearance of natriuretic peptides. Genetic variation in NPR3 has been associated with blood pressure regulation and obesity. Despite its importance, variation in NPR3 characterizing coding single nucleotide polymorphisms (SNPs) has not been addressed by resequencing the gene. Objective: We set out to identify and functionally characterize common variation in NPR3 in 3 ethnic groups. DNA samples from such subjects are studied because common genetic variation needs to be defined initially in “normal” individuals prior to studying drug effect and response. Also, rare variants identified by sequencing are enriched in complex disease traits. Methods and Results: DNA samples from 96 European-American, 96 African-American, and 96 Han Chinese-American healthy subjects were used to resequence NPR3. There were 105 polymorphisms identified of which 50 were novel, including 8 nonsynonymous (ns) SNPs of which 7 were novel. Expression constructs for the nsSNPs were created and HEK-293 cells were transfected with constructs for wild type (WT) and the variants. Recombinant proteins were analyzed by quantitative Western blot analysis. A significant reduction in NPR3 immunoreactive protein (60% or less of WT) was observed for the following variants Cys3, Arg146, Val499, and Ser477+Asp521. The Arg146 novel polymorphism resulted in the least protein expression (20% of WT). After treatment of WT and Arg146 cells with proteasome (MG132) and autophagy (3MA) inhibtors, it was determined that autophagy and not proteasomes plays an important role in the degradation of the Arg 146 variant protein. Modeling based on the NPR3 x-ray crystallography structure confirmed that the Arg146 variant were not compatible with WT conformation and could result in protein misfolding or instability. Conclusions: Multiple novel polymorphisms of NPR3 were identified in 3 ethnic groups. There were 4 variant receptors that displayed a significant decrease in NPR3 protein quantity, Arg146 being the variant with the least expression. Degradation of the variant Arg146 was mediated predominantly by autophagy. This SNP could have a significant effect on the metabolism of natriuretic peptides with clinical implications.

Clinical Pharmacology & Therapeutics (2003) 73, P77–P77; doi:

Abstract Germline mutations in several cancer predisposition genes included in hereditary multigene testing panels have been associated with increased breast cancer risk. However, estimates of breast cancer risks for each gene have in large part been derived from studies of high-risk populations enriched for family history of breast and ovarian cancer, young age of breast cancer diagnosis, or founder mutations. The breast cancer risks associated with mutations in many of these genes in the general population remain to be clearly defined. As clinical hereditary cancer genetic testing is already provided to many women at increased risk and may soon be offered to all breast cancer patients, population-based risk estimates associated with predisposition gene mutations will be needed for appropriate clinical management of mutation carriers. The “CAnceR RIsk Estimates Related to Susceptibility” (CARRIERS) consortium of 17 cohort-based case-control, population-based case-control, and family studies focused on estimation of population-based breast cancer risks and penetrance analysis for mutations in known and candidate breast cancer predisposition genes. Germline DNA from 39486 breast cancer cases and 35868 matched controls was subjected to dual bar-coded QIAseq multiplex amplification of 1733 target regions in 37 predisposition genes. Products from sets of 768 samples were pooled and sequenced in each lane of a HiSeq 4000 system. Mutations were called by GATK Haplotype Caller and Verdict. High quality sequence data was obtained for 99.3% of target regions. Here we report on results from 34741 population-based breast cancer cases and 32728 matched unaffected controls. The mean age of breast cancer diagnosis for cases was 61.2 years and mean age for controls was 61.1 years. Overall, 20.9% of cases and 14.3% of controls had a family history of breast cancer. Furthermore, 74.3% of cases and 75.8% of controls were non-Hispanic white, whereas 13.3% of cases and 15.3% of controls were African American. Among cases with tumor information available, 81.7% were ER-positive and 7.7% were triple negative breast cancers (TNBC). We assessed mutation frequencies in 24 genes including 12 established breast cancer predisposition genes (ATM, BARD1, BRCA1, BRCA2, CDH1, CHEK2, NF1, PALB2, PTEN, RAD51C, RAD51D, andTP53). The overall mutation frequency was 6.2% in cases and 2.7% in controls. Case-control association analysis after adjusting for study, age, family history of breast cancer, and race/ethnicity showed that BRCA1(OR=7.45; 95%CI:5.24-10.95) and BRCA2(OR=5.31; 95%CI:4.15-6.88) were associated with high risks of breast cancer in the general population. However, PALB2mutations were only associated with moderate risks (OR=3.63; 95%CI:2.57-5.26). ATMmutations conferred attenuated risks (OR=1.83; 95%CI:1.47-2.28) relative to studies of high-risk families or young onset breast cancers. NBNmutations were not associated with increased breast cancer risk. Mutations in BARD1, RAD51C, RAD51Dand XRCC2were specifically significantly associated with moderate risks of ER-negative breast cancer and TNBC, whereas mutations in ATM, CDH1and CHEK2were specifically significantly associated with ER-positive disease. On the basis of these findings age-related absolute breast cancer risks for commonly mutated genes were estimated. Overall, results from the CARRIERS study establish that mutations in predisposition genes are associated with lower risks of breast cancer in the general population than in enriched populations including high-risk families and young onset, bilateral, or multiple primary cases. We anticipate that the results from this study will inform cancer screening and other risk management strategies for women in the general population with mutations in predisposition genes. Citation Format: Fergus J Couch, Chunling Hu, Steven N Hart, Rohan Gnanaolivu, Kun Y Lee, Jie Na, Chi Gao, Nicholas J Boddicker, Bruce Eckloff, Raed Samara, Josh Klebba, Christine B Ambrosone, Hoda Anton-Culver, Paul Auer, Leslie Bernstein, Mia M Gaudet, Christopher Haiman, Esther M John, Susan Neuhausen, Janet E Olson, Tuya Pal, Julie R Palmer, Dale P Sandler, Jack A Taylor, Amy Trentham-Dietz, Celine M Vachon, Clarice Weinberg, Song Yao, Jeffrey N Weitzel, David E Goldgar, Susan M Domchek, Katherine L Nathanson, Peter Kraft, Eric C Polley. Population-based breast cancer risk estimates for predisposition gene mutations: Results from the CARRIERS study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PD3-01.

7568 Background: The molecular events in the initiation and progression of invasive lung adenocarcinoma remain poorly characterized. These tumors are thought to develop through an adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), invasive adenocarcinoma (AD) sequence. The goal of our study was to assess lineage relationships between in situ and invasive components within adenocarcinomas with prominent lepidic growth patterns. Methods: Frozen tissue from fourteen lung adenocarcinomas with mixtures of AD together with an adjacent in situ component (AIS), varying in ratio between 40 to 80%, were selected from our Lung Specimen Registry. Laser capture microdissection (LCM) of each component was performed separately for each tumor. Genomic DNA was isolated using a direct in situ whole genome amplification (WGA) methodology, and Next Generation Sequencing performed using an Illumina Mate Pair (MP) library protocol. MP sequence reads were mapped to the human genome and primers spanning the fusion junctions were used in validation PCRs. Results: Genomic break points identical and unique to a specific patient were identified between the AIS and AD components in 13 (of 14) cases. The total number of events per case ranged from 4-215, and the number of identical events shared between the AIS and AD components ranged from 30 to 90%. Recurrent genomic breakpoints between cases were also observed, with the 2 most common involving 8q24.3 in 5 cases and FAM19A2 on chromosome 12 in 4 cases. PCR validation of selected genomic alterations confirmed the genomic break points identified from sequencing in both the AIS and AD in all cases. Interestingly, we also observed a limited number of genomic alterations present in a zonal distribution of surrounding normal lung around the tumor mass. Conclusions: Our study demonstrates unique chromosomal alterations present in both the AIS and AD components of individual lung tumors with features of lepidic growth. These data provide evidence for lineage relationship and clonal relatedness between the two components, and provide genomic evidence for a model of stepwise progression from AIS to invasive AD in this subset of lung adenocarcinomas.

Abstract Abstract 633 Background: To date, the only well characterized chromosomal translocations among peripheral T-cell lymphomas (PTCLs) are those involving ALK, which occur in about half of anaplastic large cell lymphomas (ALCLs). ALK-negative ALCLs remain poorly understood, despite morphology and phenotype similar to ALK-positive ALCLs. We recently described translocations near IRF4 on 6p25.3 in cutaneous ALK-negative ALCLs. In the present study, we utilized massively parallel (Next Generation) sequencing to answer three questions about these translocations: (1) Were they recurrent in the more lethal systemic form of ALK-negative ALCL? (2) What was the translocation partner? (3) What were the likely genetic consequences? Methods: We used a mate pair library approach to juxtapose DNA sequences originally lying ~5 kb apart: these paired sequences map to distinct areas of the genome if a translocation breakpoint lies between them. Because only the ends of the original DNA fragments are sequenced, this approach is more resource efficient than whole genome sequencing. Genomic DNA from a systemic ALK-negative ALCL with an uncharacterized 6p25.3 rearrangement was fragmented to 2–5 kb, biotinylated, and separated on an agarose gel. Fragments ~5-5.5 kb were excised, purified, circularized, and further fragmented to ~300-600 bp. Fragments containing biotin (representing the ends of the original 5 kb fragments) were immobilized on streptavidin beads and amplified using the Illumina library protocol. Paired end sequencing was performed on one lane of a flow cell on an Illumina GAIIx. Sequencing data were mapped to the genome using a binary indexing algorithm. Non-mapping and duplicate sequences were discarded. Candidate translocations suggested by >4 unique mate pairs were examined by BLAT to exclude false positives explained by mapping to homologous regions. PCR and Sanger sequencing of tumor DNA was used for validation. Fluorescence in situ hybridization (FISH) was performed on additional PTCLs. mRNA and miRNA expression was quantified using real-time PCR. Results: Of 28.90×106 paired sequences, 8.61×106 were non-duplicate pairs in which both ends mapped to the human genome (bridged coverage, ~7x). Only one candidate translocation involved 6p25.3, represented by 10 unique mate pairs. PCR and Sanger sequencing confirmed a balanced translocation: one breakpoint disrupted the dual-specificity phosphatase gene, DUSP22, telomeric to IRF4 on 6p25.3; the other was telomeric to the FRAH7 fragile site on 7q32.3. Additional ALK-negative ALCLs with known 6p25.3 rearrangements were tested using a 7q32.3 breakapart FISH probe, which showed a 7q32.3 rearrangement in 13/29 (45%; 7 systemic and 6 cutaneous). Dual fusion FISH confirmed t(6;7)(p25.3;q32.3) in 11/11 cases tested. None of 120 PCTLs (including 39 ALCLs) lacking 6p25.3 rearrangements had a 7q32.3 rearrangement. Levels of 5′ and 3′ DUSP22 mRNA in cases with 6p25.3 rearrangements were decreased relative to those in non-rearranged cases (5′: 0.02±0.01 vs 1.00±0.74, p=.002; 3′: 0.09±0.08 vs 1.00±0.55, p=.0002; mean±SD, t test). IRF4 mRNA levels were similar in both groups. Levels of MIR29A and MIR29B1 within FRAH7 in cases with 7q32.3 rearrangements were increased relative to those in non-rearranged cases (MIR29A: 2.44±2.20 vs 1.00±1.34, p=.15; MIR29B: 4.93±4.68 vs 1.00±1.05, p=.007). Conclusions: The t(6;7)(p25.3;q32.3) is the first recurrent translocation characterized in systemic and cutaneous ALK-negative ALCLs. This translocation was entirely specific for ALK-negative ALCLs, and was present in 45% of cases with 6p25.3 rearrangements. The t(6;7)(p25.3;q32.3) was associated with down-regulation of DUSP22 and up-regulation of MIR29, but not dysregulation of IRF4. DUSP22 inhibits mitogen activated protein kinase activity in T cells, and may represent a novel tumor suppressor in ALCLs. Increased MIR29 levels may additionally contribute to tumorigenesis, as recently shown in acute myeloid leukemias. Finally, clinical testing for t(6;7)(p25.3;q32.3) may aid in differentiating ALK-negative ALCL from other PTCLs. Our findings highlight the utility of mate-pair library sequencing to discover novel translocations in lymphoma and other cancers. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1814 Multiple myeloma (MM) is an incurable hematologic disorder characterized by the accumulation of plasma cells (PCs) in the bone marrow (BM). Like normal B cells and PCs, MM cells express a distinctive immunoglobulin (Ig) molecular fingerprint resulting from heavy and light chain gene rearrangements and unique mutations introduced by the somatic hypermutation (SHM) process. Detailed examination of the Ig molecule may offer insight into the etiology of B cell malignancies as well as the ontogeny of malignant transformation and ongoing genetic evolution. Because prior studies of the Ig fingerprint of MM cells have been limited in size and scope, our current understanding of MM Ig repertoire is minimal. We used massively parallel sequencing of normal and malignant PCs to interrogate: 1) DNA versus RNA (cDNA) as starting material for studies of Ig repertoire; 2) the Ig repertoire of normal and malignant PCs; and 3) intraclonal heterogeneity in MM. Bone marrow PCs (BMPCs) from an untreated MM patient and from a normal control subject were isolated by magnetic bead separation. DNA and RNA were isolated from purified cells and amplified in a multiplex PCR reaction with primers designed to capture the entire IGHV region including the heavy chain complementarity determining region 3 (HCDR3) necessary for defining clonal cells. Using Roche 454 GS-FLX Titanium chemistry and a GS FLX Titanium Genome Sequencer, over 30,000 sequence reads were obtained from each sample. Following a detailed algorithm to minimize Taq and sequencing related errors and removal of non-Ig or non-productive Ig sequences, the resulting sequences were grouped based on HCDR3 amino acid identity. Each unique HCDR3 represented one member of the repertoire and all the sequences with the same HCDR3 defined the clone size. This measurement showed that there was nearly a five-fold higher level of unique HCDR3s in normal BMPCs when the starting PCR template was DNA vs. cDNA. Thus, DNA is clearly a better starting template for repertoire analysis using deep sequencing methods. Thorough analysis of the MM DNA sample identified PCs expressing 37 different IGHV genes, and predictably, the vast majority of sequence reads (83%) had exact nucleotide identity in the IGHV and HCDR3 region (IGHV3-74 with 18 mutations in the IGHV region) thereby defining the dominant MM clone. There were also ∼5000 additional sequences that either shared an identical HCDR3 region but varied within the IGHV3-74 gene sequence (n=3975) or were identical within the IGHV3-74 sequence yet varied within the HCDR3 (n=862). These sequences were further analyzed, with sequences not present 10 or more times or not found in both the 5' and 3' directions eliminated from further scrutiny. This process revealed a total of 64 putative subclones with single point mutations in the IGHV or HCDR3 region (10–56 copies of each unique sequence representing a total of 1583 clonally related sequences). When we used a more stringent subclone frequency of ≥0.1%, 22 subclones remained. Of note, conventional Ig repertoire analysis would require sequencing ≥1000 colonies to detect MM subclones present at this frequency. Finally, 11 subclones displayed a significant number of IGHV gene nucleotide differences from the dominant MM clone despite exhibiting an identical HCDR3 region. Notably, a number of these distinguishing IGHV gene mutations are silent and thus may preserve the antigenic specificity of these clonally related cells. These subclones failed our frequency criteria but the type and quality of deviations from the clonal sequence suggest that they are not artifact and warrant further investigation. Notably, all of the putative subclones were also found in the MM cDNA cohort providing further evidence as genuine subclones. The very large number of identical MM clonal sequences is consistent with the idea that MM is a post germinal center malignancy that can no longer undergo SHM. However, we present clear evidence of MM-related subclones albeit relatively small in number. The subclone sequence deviations discovered may reflect on-going genetic evolution independent of the formal SHM mechanism. Alternatively, these subclones may indeed reflect “sister” cells generated during the original germinal center reaction that resulted in the malignant clone. In summary, our studies demonstrate the extraordinary potential of this methodology to track clonal evolution in MM and its precursor conditions over time. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Peripheral T-cell lymphomas (PTCLs) comprise a heterogeneous group of relatively uncommon and generally aggressive non-Hodgkin lymphomas. Recent studies have begun to reveal their mutational landscape, such as the recurrent mutations affecting RHOA, IDH2, and TET2 in angioimmunoblastic T-cell lymphomas (AITLs) and related PTCLs. Here, we studied the exomes of 63 PTCLs to address several unanswered questions: (1) How frequently do PTCLs have mutations with a strong rationale for being actionable using clinically available targeted therapies? (2) What pathways are enriched in PTCLs that could point to additional targeted therapies? (3) What additional recurrent mutations exist that may provide insight into PTCL pathogenesis and classification? Methods: We performed exome capture and sequencing in 63 frozen PTCL samples (with matched germline controls from 22), including 13 PTCLs, not otherwise specified; 6 AITLs; 37 anaplastic large cell lymphomas (ALCLs: 12 ALK+, 19 ALK-, and 6 cutaneous); 4 extranodal NK/T-cell lymphomas; 2 cutaneous T-cell lymphomas, and 1 enteropathy associated T-cell lymphoma. Following primary variant calling, data were filtered by removing variants that were: outside the capture region, polymorphic (0.1% in ExAC), seen in paired germline or 50 healthy controls, within repetitive elements, or synonymous. Potentially actionable variants required published evidence for altering protein function and demonstrated in vivo or in vitro sensitivity to an available targeted agent (including open clinical trials). Mutated cancer genes (COSMIC) were examined for enrichment of KEGG canonical signaling pathways. A recurrent mutation encoding MSC E116K was validated in tumor DNA and MSC protein was examined by immunohistochemistry. Results: Of 25 unique variants with published evidence suggesting actionability (including ErbB, JAK/STAT, and RAS genes), at least one variant was present in 16/63 patients (25%). Variants in any COSMIC gene were seen in 55/63 samples (87%). Top genes were STAT3, RHOA, ARID1A, MLL2 (KMT2D), PTPRB, TP53, and TET2. The KEGG ErbB pathway was most significantly enriched for mutated genes in our dataset (EGFR, ERBB2, ERBB3, ERBB4, and others; q=3.88x10-3), followed by neurotrophin and mitogen-activated protein kinase signaling pathways. Among 25 recurrent non-synonymous variants, we identified MSC E116K with predicted gain-of-function exclusively in 3 ALK-ALCLs and 1 cutaneous ALCL. All mutated cases strongly expressed MSC protein. Among 96 cases, 13/18 ALK-ALCLs (72%) were positive for MSC, compared to 9/78 (12%) from other PTCL subtypes. Conclusions: Mutations that were potentially actionable based on published variant-specific data were identified in 25% of PTCLs, indicating promise for the role of sequencing in individualizing therapy. Additionally, remaining variants were enriched for several targetable pathways, most significantly ErbB. A novel recurrent mutation, MSC E116K, was seen exclusively in ALK-ALCLs (systemic and cutaneous). MSC protein, a repressor of E2A-mediated transcription of targets such as MYC, was expressed in most ALK- ALCLs and generally was absent in other PTCL subtypes. This finding extends evidence for a genetic relationship between systemic and cutaneous ALCLs and suggests MSC may help distinguish ALK- ALCLs from other PTCLs. Disclosures Link: Genentech: Consultancy, Research Funding; Kite Pharma: Research Funding.

Abstract Background Next Generation sequencing (NGS) is a powerful tool to identify somatic mutations associated with tumor onset and drug response. While it is well suited for high quality fresh/frozen samples, NGS is not proven for FFPE tissue which is the most common type of clinical specimen. Since the nucleic acids can be readily extracted from FFPE samples for a variety of genomic analyses, a comparative mutational analysis of paired frozen and FFPE tissues is urgently needed. Our long term goal is to establish a lab protocol to detect mutations in FFPE tumors using a targeted capture and sequencing approach for genes of interest. This pilot study focuses on the comparison of FFPE and frozen samples to test the validity of using FFPE tissues in such application. Methods Gene Selection: 128 genes associated with known pathogenic mutations in lymphoma Sample Selection: 9 diffuse large B-cell lymphoma (DLBCL) cases with FFPE, frozen and germline samples, as well as 10 frozen normal lymphatic tissues as references for CNV detections Capture Probe Design: We targeted coding exons and UTR, as well as the evolutionarily conserved intronic regions. The capture probes were designed using the Agilent eArray tool. The titling density of the probes was set to 3 probes overlapping with every base in the target region to improve the capture efficiency in FFPE samples. The least stringent masking of the repeat regions was allowed to include regions with small repeats that are shorter than the length of the sequencing reads (100-bp). In addition, boosting parameters were picked to set various levels of probe replication in different regions in order to minimize the local coverage differences (e.g. between regions of different GC contents) Sequencing and Bioinformatics: The target capture and sequencing were performed by the Mayo Clinic Medical Genome Facility. The reads were mapped to Human Reference Genome Build 37 using Novalign, and SNVs were called using GATK. The CNVs were identified using an in-house developed algorithm, patternCNV. Results The designed probes covered 99.65937% of the target regions. We generated 2.2-6.7 Gbp of reads per sample, 57.4-71.5% of which were on target. This equalled an average coverage of 2100-6700 folds which is 10-30 times higher than the minimal coverage recommended by Agilent. Due to this high coverage, we observed duplicate reads that accounted for 7.7-73.5% of the total reads. When we analysed the data with and without the duplicated reads, the concordance of the called SNVs was between 84-93% out of 207-249 mutated positions per trio-sample. There were 7.8-8.9% and 1.1-2.2% unique SNVs per sample by excluding or including duplicate reads, respectively. The dis-concordances were mostly missed calls, where a SNV was observed in only 1 or 2 of the trio samples. The missed calls from frozen samples ranged from 0-10.4% compared to 1.4-10.4% from the FFPE tissues, with 0.88-2.4% more SNVs missed in FFPE. Further analyses showed that all of the missing calls came from the lack of or low coverage of the corresponding positions. There were also differences of the called SNVs between the trio samples. However, this was extremely rare. Only 2 out of the 9 trio samples at a total of 3 positions had disagreements in called SNVs between FFPE and frozen tissues, all due to the allelic imbalance where the percentage of reads supporting the alternative alleles were below 20%. Therefore, this dis-concordance can be removed by back-filling of the read-level information for each position. Unfortunately only 11.9-47.4% of the CNVs called in frozen tissues were identified in FFPE samples, due to the widely various coverage in FFPE samples. The consequent large noises of the log ratio values between the FFPEs and normal references significantly reduced the sensitivity for CNV calling. Conclusions This pilot study compared the performance of SNV and CNV detection in FFPE and paired frozen tissues using a target capture and sequencing approach. With a capture probe design strategized to benefit FFPE samples, we observed SNV detection rates in FFPE that were only slightly lower (0.88-2.4%) than those of frozen tissues due to poor coverage of some positions in FFPE samples. With a proper back-filling step, there was no dis-concordance of the called SNVs between FFPE and frozen samples. However, CNV detections in FFPE were more problematic due to the un-predictable regional coverage in FFPE samples. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Understanding the joint effect on breast cancer risk of rare pathogenic variants in cancer predisposition genes and polygenic risk scores (PRS) from common variants can enable a precision approach to breast cancer management. Previous work found that PRS were associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers recruited from cancer genetics clinics (Kuchenbaecker et al. JNCI 2017). The joint effects of pathogenic variants and PRS have not been studied in samples drawn from the general population. There is also no existing study evaluating the effect of PRS in mutation carriers in genes other than BRCA1/2. Here we evaluate the joint effects of PRS and pathogenic mutations in established cancer predisposition genes in a population-based case-control sample. Method: We analyzed 53,199 European-ancestry individuals (20,730 controls and 21,272 cases) drawn from 7 cohorts and 2 population-based case-control studies in the CAnceR RIsk Estimates Related to Susceptibility” (CARRIERS) consortium. Targeted sequencing was performed using dual bar-coded QIAseq. Mutation calling was conducted with Haplotype Caller and Vardict. We sequenced 18 breast cancer predisposition genes: ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CDKN2A, CHECK2, FANCC, MLH1, MSH2, MSH6, NF1, PALB2, PTEN, RAD51C, RAD51D and TP53. The PRS was calculated based on 128 common variants using effect estimates from the largest published breast cancer GWAS. The PRS was standardized to a mean of 0 and standard deviation of 1. Logistic regression was performed to assess the combined effect of identified mutation and common variants (including main and interaction effects for carrier status and PRS). Results: A total of 1,770 pathogenic mutations were observed. About 1% of the study sample had mutations in either BRCA1 (n=209) or BRCA2 gene (n=305), and 2.2% had mutations in other genes (n=1,176). The effect of PRS in BRCA1 carriers was OR= 0.97 (95%CI: 0.62, 1.52); however, this is not statistically significantly different from the PRS in non-carriers [OR=1.23 (95%CI: 1.20, 1.25)] or previous estimates in carriers [OR: 1.14, 95%CI: 1.11-1.17]. The effect of PRS in BRCA2 carriers was OR=1.87 (95%CI: 1.31, 2.78) which was statistically significantly different from that of the non-carriers. Among the mutation carriers in genes other than BRCA, the effect of PRS on breast cancer was OR=1.00 (95%CI: 0.88,1.15). Conclusion: Consistent with previous studies, we did not find evidence that the effect of the PRS among BRCA1 carriers was statistically significantly different than non-carriers. We found some evidence that the PRS effect may be larger among BRCA2 carriers than non-carriers. Our results also suggest that PRS may not have a strong effect on breast cancer risk in mutation carriers of other predisposition genes; further work is needed for verification. Citation Format: Chi Gao, Chunling Hu, Steven N. Hart, Rohan Gnanaolivu, Kun Y. Lee, Jenna Lilyquist, Nicholas J. Boddicker, Bruce Eckloff, Raed Samara, Josh Klebba, Paul Auer, Leslie Bernstein, Mia Gaudet, Hoda Anton-Culver, Amy Trentham-Dietz, Julie R. Palmer, Song Yao, Christopher Haiman, Janet E. Olson, Susan Domchek, Jeffrey Weitzel, David Goldgar, Katherine L. Nathanson, Eric C. Polley, Fergus J. Couch, Peter Kraft. The joint effects of polygenic risk scores and pathogenic variants in cancer predisposition genes on breast cancer risk in the general population: results from the CARRIERS study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4177.