Common Susceptibility Loci Research Articles

Common Hyperglycemia Susceptibility Loci in Metabolic Syndrome Patients from Karachi, Pakistan: A Cross Sectional Study

Background: More than 75 genetic susceptibility loci have been implicated with hyperglycemia. SNPs in genes linked with satiety, insulin sensitivity, BMR (Adiponectin, FTO, and MC4R), and inflammation and autoimmunity (TNF-a) have been shown to have a relationship with metabolic syndrome. Objectives: To measure the frequency of ADIPOQ, FTO, MCR4, and TNF SNPs in metabolic syndrome patients and controls, and to assess the association of these with hyperglycemia and adiposity status. Methods: A cross-sectional study was conducted. Baseline investigations including lipid profiles, blood glucose levels, and BMI calculation were conducted for n=113 Metabolic Syndrome and n=47 healthy controls. Tetra ARMS PCR and gel electrophoresis were conducted for Adiponectin rs266729, Adiponectin rs1501299, FTO rs9939609, MCR4 rs1297013, and TNF rs1800629. Statistical analysis was performed using SPSS version 26. Results: Difference was observed in lipid profiles (including LDL, triglycerides, and cholesterol but not HDL), body fat percentage (p= 0.034), and both fasting (p=0.000) and random (p=0.000) blood glucose levels among metabolic syndrome patients versus controls. Adiponectin rs1501299, FTO rs9939609, and MCR4 rs1297013 showed genotype frequency differences between groups. Spearman’s correlation was applied to test any association of risk allele with study variables and MCR4 rs1297013 showed an independent association with Fasting Blood Glucose Level (r=0.238; p=0.024) irrespective of age, weight, or gender. Conclusion: MCR4 rs1297013 polymorphism is an independent risk factor leading to hyperglycemia in the study population, however, no other SNPs were identified to carry a significant risk. Large-scale genome-wide studies are required to identify the unique set of risk genes for the Pakistani population

Abstract PO4-19-02: Genetic risk estimation in breast cancer and assessing health disparities

Abstract Background: Breast Cancer (BC) incidence and the distribution of BC risk factors vary between racial and ethnic groups within the United States. It has been demonstrated that providing education on individualized breast cancer risk will improve patient uptake to recommended BC screening and prevention strategies. Most clinical risk assessment tools, including the validated IBIS model were derived from data using non-Hispanic white women. Consortia have also now identified over 300 common genetic susceptibility loci for BC, summarized by the polygenic risk score (PRS). When combined with clinical risk assessment tools, such as the IBIS or BCRAT models, the PRS can further refine risk estimation for patients. To date, most studies on the use of PRS have been done in non-Hispanic white women. While these PRS still perform well in racial minorities, there has been a recognized need to improve racial and ethnic diversity in genomic research cohorts. Herein, we aim to combine clinical risk assessment models that are already used in routine clinical practice with information derived from PRS testing in women of racial minorities to determine if this can improve risk estimation, patient understanding, and uptake to recommended breast cancer screening and prevention strategies. Design: This is a minimal risk prospective study with a single arm incorporating the PRS into a standard breast cancer risk reduction consultation, followed by annual surveys over 10 years to determine if and how the information provided by the PRS influenced patient decisions regarding recommended BC screening and prevention. Patients will have IBIS and BCRAT risks calculated at baseline visit. A survey of patient perceptions/understanding of risk, intention to undergo screening, and use of preventive medicine is completed after baseline visit prior to receiving the PRS results. Blood sample is obtained at baseline and DNA samples are analyzed for approximately 300 SNPs on a custom-designed, targeted SNP panel from ThermoFisher Scientific by the Mayo Clinic Genomics Laboratory. This PRS result is then combined with the clinical risk assessments (IBIS and BCRAT scores) using the R package Individualized Coherent Absolute Risk Estimators (iCare) tool to provide a new estimate of breast cancer risk for 5year, 10year, and lifetime risk. Patients are seen for follow-up to review results and then complete a second survey to assess their understanding of the results, BC risk, and how the PRS impacted their decision to undergo screening/prevention strategies. Eligibility Criteria: Women who self-identify as African American/Black or Hispanic/Latinx between 30-75 years old with any of the following: 1.)IBIS score of ≥5% for the 10 year risk OR BCRAT score of ≥ 3 % for the 5 year risk. 2.) History of biopsy proven atypical hyperplasia 3.) History of biopsy proven lobular carcinoma in situ. Specific Aims: Aim 1: The primary aim of this study is to explore if the addition of PRS to the BCRAT and IBIS score will improve intentions to undergo recommended breast cancer screening strategies such as mammography, MRI, or molecular breast imaging in women of underserved racial minorities Aim 2: To explore if the addition of the PRS to the BCRAT and IBIS risk score will aid women of racial minorities in deciding whether to take preventative endocrine therapy. Aim 3: To understand how individualized risk assessment and information on PRS may alter perceived risk of breast cancer. Statistical Methods Analysis will be mostly descriptive. Continuous variables will be summarized as mean (standard deviation) or median (range) and categorical variables will be reported as frequency (percentage). Kaplan-Meier method will be used to estimate the long-term cumulative risk of cancer. Current Accrual: 3. Target Accrual: 50 Citation Format: Lauren Cornell, Sandhya Pruthi, Linda Hasadsri, Sarah McLaughlin. Genetic risk estimation in breast cancer and assessing health disparities [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-19-02.

Interpretation of 10years of Alzheimer's disease genetic findings in the perspective of statistical heterogeneity.

Common genetic variants and susceptibility loci associated with Alzheimer's disease (AD) have been discovered through large-scale genome-wide association studies (GWAS), GWAS by proxy (GWAX) and meta-analysis of GWAS and GWAX (GWAS+GWAX). However, due to the very low repeatability of AD susceptibility loci and the low heritability of AD, these AD genetic findings have been questioned. We summarize AD genetic findings from the past 10years and provide a new interpretation of these findings in the context of statistical heterogeneity. We discovered that only 17% of AD risk loci demonstrated reproducibility with a genome-wide significance of P < 5.00E-08 across all AD GWAS and GWAS+GWAX datasets. We highlighted that the AD GWAS+GWAX with the largest sample size failed to identify the most significant signals, the maximum number of genome-wide significant genetic variants or maximum heritability. Additionally, we identified widespread statistical heterogeneity in AD GWAS+GWAX datasets, but not in AD GWAS datasets. We consider that statistical heterogeneity may have attenuated the statistical power in AD GWAS+GWAX and may contribute to explaining the low repeatability (17%) of genome-wide significant AD susceptibility loci and the decreased AD heritability (40-2%) as the sample size increased. Importantly, evidence supports the idea that a decrease in statistical heterogeneity facilitates the identification of genome-wide significant genetic loci and contributes to an increase in AD heritability. Collectively, current AD GWAX and GWAS+GWAX findings should be meticulously assessed and warrant additional investigation, and AD GWAS+GWAX should employ multiple meta-analysis methods, such as random-effects inverse variance-weighted meta-analysis, which is designed specifically for statistical heterogeneity.

FRI455 Polycystic Ovary Syndrome-Associated DENND1A Non-Coding Risk Loci Alter Gene Expression

Abstract Disclosure: L. Sankaranarayanan: None. G. Johnson: None. A. Barrera: None. A.E. Dunaif: None. T. Reddy: None. Polycystic ovary syndrome (PCOS) is a leading cause of infertility and type 2 diabetes affecting 10-15% of menstruating people worldwide. PCOS is characterized by increased circulating testosterone levels, ovulatory dysfunction and insulin resistance. Genome wide association studies (GWAS) have identified ∼20 replicated common PCOS susceptibility loci in European and Han Chinese cohorts. The associated variants are predominantly non-coding and implicate neuroendocrine, reproductive, and metabolic causal pathways. Rare non-coding variants in DENND1A, a GWAS candidate gene that regulates androgen biosynthesis, were present in ∼50% of PCOS families by whole genome sequencing. These associations suggest non-coding genetic contributions to the development of PCOS. We tested the hypothesis that PCOS GWAS risk loci contribute to PCOS pathogenesis by altering gene regulation. We first identified ∼1500 functioning regulatory elements across the GWAS associated regions using a high throughput reporter assay, STARR-seq, in two different cell lines. We used H295R, an adrenal cell line model for testosterone production and COV434, an ovarian granulosa cell line. We identified cell-line specific and overlapping regulatory regions suggesting that there is context specific gene regulation. Sixty percent of the identified regions are in previously documented open chromatin regions from DNase-seq and ATAC-seq studies supporting our hypothesis that these regulatory regions are functional. We additionally experimentally tested the regulatory effect of five of the regulatory regions identified in the DENND1A locus in H295R cells using CRISPR-based epigenetic editing tools. This endogenous perturbation increases DENND1A gene levels (measured by qPCR) and also increased testosterone produced by the H295R cells (measured by ELISA), suggesting that these regions are biologically relevant to PCOS pathogenesis.We investigated allele-specific regulatory activity in a multi-ethnic pool of five genomes from healthy individuals. We identified 21 common genetic variants (minor allele frequency in the population &amp;gt;0.05) that alter regulatory activity in the DENND1A locus, including two that are ancestry-specific. Further, rs12237685 and rs28441318 are also eQTLS for DENND1A from the GTEX project and reside within open chromatin regions in ovarian cells. The functional consequences of non-coding genetic variants associated with complex traits has been exceptionally difficult to elucidate. Our findings suggest that both the common genetic variants and rare PCOS patient-associated DENND1A variants and altered gene expression. Further, some of those variants may contribute to allele-specific genetic risk for PCOS. Presentation Date: Friday, June 16, 2023

Abstract 5218: Genome-wide association study of African Americans reveals new susceptibility loci contributing to lung cancer and mechanisms of population-specific etiology

Abstract Lung cancer incidence and mortality in the U.S. have substantial ethnic disparities. African Americans of both sexes have the high incidence rate at 56.8 and the highest death rate at 38.1 per 100,000 people from 2015 to 2019. Non-Hispanic black men have the highest incidence at 73.9 and the highest death rate at 56.3 per 100,000 people. While many genome-wide association studies (GWAS) of lung cancer have discovered ~45 putative risk loci, a large proportion of the heritability of lung cancer remains unexplained. To date, most single population-based GWAS have been performed in Europeans while there are a few Asian ancestry-specific genetic studies and two cross-ancestry studies. Non-European GWAS of lung cancer has been underrepresented. Although African Americans have higher lung cancer incidence and poorer lung cancer survival rate, and smoke fewer cigarettes per day compared to Europeans, few comprehensive GWAS of lung cancer in African Americans has been conducted. This study aims to decipher the genetic component of predisposition to lung cancer among African Americans. This study aims to decipher the genetic component of predisposition to lung cancer among African Americans. We conducted an African-ancestry GWAS comprising 2,280 lung cancer cases and 4,301 controls to comprehensively characterize common and low-frequency lung cancer genetic susceptibility loci using HRC imputed lung cancer data. The novel variants in or near VWF on 12p13.31 (OR=1.29, P=6.93 × 10−9) for overall lung cancer and GACAT3 on 2p24.3 (0.65, 1.24 × 10−9), TRIP13 on 5p15.33 (3.49, 1.00 × 10−8), ERC1 on 12p13.33 (4.64, 6.08 × 10−9), LMAN1L (near CYP1A1) on 15q24.1 (4.25, 8.71 × 10−9) for lung squamous cell cancer were identified at a genome-wide significance level. Our GWAS of lung cancer identified five novel genetic susceptibility associations and confirmed several variants on 15q25 and 19q13. Further works are required to elucidate the possible biological mechanisms underlying these associations among lung cancer and histological subtypes in African Americans. Citation Format: Jinyoung Byun, Younghun Han, Xiangjun Xiao, Christine Lusk, Hoda J. Badr, Rayjean Hung, Ann G. Schwartz, Christopher I. Amos, INTEGRAL Consortium. Genome-wide association study of African Americans reveals new susceptibility loci contributing to lung cancer and mechanisms of population-specific etiology. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5218.

A Genome-Wide Association Study Identified Novel Genetic Susceptibility Loci for Oral Cancer in Taiwan.

Taiwan has the highest incidence rate of oral cancer in the world. Although oral cancer is mostly an environmentally induced cancer, genetic factors also play an important role in its etiology. Genome-wide association studies (GWAS) have identified nine susceptibility regions for oral cancers in populations of European descent. In this study, we performed the first GWAS of oral cancer in Taiwan with 1529 cases and 44,572 controls. We confirmed two previously reported loci on the 6p21.33 (HLA-B) and 6p21.32 (HLA-DQ gene cluster) loci, highlighting the importance of the human leukocyte antigen and, hence, the immunologic mechanisms in oral carcinogenesis. The TERT-CLMPT1L locus on 5p15.33, the 4q23 ADH1B locus, and the LAMC3 locus on 9q34.12 were also consistent in the Taiwanese. We found two new independent loci on 6p21.32, rs401775 in SKIV2L gene and rs9267798 in TNXB gene. We also found two suggestive novel Taiwanese-specific loci near the TPRS1 gene on 8q23.3 and in the TMED3 gene on 15q25.1. This study identified both common and unique oral cancer susceptibility loci in the Taiwanese as compared to populations of European descent and shed significant light on the etiology of oral cancer in Taiwan.

Rare germline deleterious variants increase susceptibility for lung cancer.

Although multiple common susceptibility loci for lung cancer (LC) have been identified by genome-wide association studies, they can explain only a small portion of heritability. The etiological contribution of rare deleterious variants (RDVs) to LC risk is not fully characterized and may account for part of the missing heritability. Here, we sequenced the whole exomes of 2777 participants from the Environment and Genetics in Lung cancer Etiology study, a homogenous population including 1461 LC cases and 1316 controls. In single-variant analyses, we identified a new RDV, rs77187983 [EHBP1, odds ratio (OR) = 3.13, 95% confidence interval (CI) = 1.34-7.30, P = 0.008] and replicated two previously reported RDVs, rs11571833 (BRCA2, OR = 2.18; 95% CI = 1.25-3.81, P = 0.006) and rs752672077 (MPZL2, OR = 3.70, 95% CI = 1.04-13.15, P = 0.044). In gene-based analyses, we confirmed BRCA2 (P = 0.007) and ATM (P = 0.014) associations with LC risk and identified TRIB3 (P = 0.009), involved in maintaining genome stability and DNA repair, as a new candidate susceptibility gene. Furthermore, cases were enriched with RDVs in homologous recombination repair [carrier frequency (CF) = 22.9% versus 19.5%, P = 0.017] and Fanconi anemia (CF = 12.5% versus 10.2%, P = 0.036) pathways. Our results were not significant after multiple testing corrections but were enriched in cases versus controls from large scale public biobank resources, including The Cancer Genome Atlas, FinnGen and UK Biobank. Our study identifies novel candidate genes and highlights the importance of RDVs in DNA repair-related genes for LC susceptibility. These findings improve our understanding of LC heritability and may contribute to the development of risk stratification and prevention strategies.

Interactive effect of the empirical lifestyle index for insulin resistance with the common genetic susceptibility locus rs2423279 for colorectal cancer.

The aim of this study is to examine the empirical insulinemic potential consisting of dietary and lifestyle factors and the interactive effect with the common genetic susceptibility locus rs2423279 on the risk of colorectal cancer (CRC). This case-control study was conducted with 923 CRC patients and 1846 controls. The empirical measures for assessing the insulinemic potential, namely, the empirical dietary index for hyperinsulinemia (EDIH), for insulin resistance (EDIR), the empirical lifestyle index for hyperinsulinemia (ELIH), and for insulin resistance (ELIR), were calculated based on semiquantitative food frequency questionnaire and lifestyle questionnaire. A genetic variant of rs2423279 was genotyped. The CRC patients were more likely to score in the highest quartile for the ELIH (OR 2·90, Q4 v. Q1, 95 % CI (2·01, 4·19), Pfor trend < 0·001), EDIR (OR 3·32, Q4 v. Q1, 95 % CI (2·32, 4·74), P < 0·001) and ELIR (OR 2·79, Q4 v. Q1, 95 % CI (1·96, 3·97), P < 0·001) than the controls. The significant effect between the ELIR, which assesses dietary and lifestyle patterns related to insulin resistance, and C allele carriers of rs2423279 was stronger than that for homozygous T allele carriers (OR 2·50, 95 % CI (1·78, 3·51), Pfor interaction = 0·034). The empirical insulinemic potential for insulin resistance might have interactive effects with the rs2423279 polymorphism on the risk of CRC. The results of this study suggest the basis of the metabolic impact of the insulin response on colorectal carcinogenesis.

Rare germline copy number variants (CNVs) and breast cancer risk

Germline copy number variants (CNVs) are pervasive in the human genome but potential disease associations with rare CNVs have not been comprehensively assessed in large datasets. We analysed rare CNVs in genes and non-coding regions for 86,788 breast cancer cases and 76,122 controls of European ancestry with genome-wide array data. Gene burden tests detected the strongest association for deletions in BRCA1 (P = 3.7E−18). Nine other genes were associated with a p-value < 0.01 including known susceptibility genes CHEK2 (P = 0.0008), ATM (P = 0.002) and BRCA2 (P = 0.008). Outside the known genes we detected associations with p-values < 0.001 for either overall or subtype-specific breast cancer at nine deletion regions and four duplication regions. Three of the deletion regions were in established common susceptibility loci. To the best of our knowledge, this is the first genome-wide analysis of rare CNVs in a large breast cancer case-control dataset. We detected associations with exonic deletions in established breast cancer susceptibility genes. We also detected suggestive associations with non-coding CNVs in known and novel loci with large effects sizes. Larger sample sizes will be required to reach robust levels of statistical significance.

Genetic overlap between type 1 diabetes and other autoimmune diseases.

Type 1 diabetes (T1D) is a chronic disease caused by the destruction of pancreatic β cells, which is driven by autoreactive T lymphocytes. It has been described that a high proportion of T1D patients develop other autoimmune diseases (AIDs), such as autoimmune thyroid disease, celiac disease, or vitiligo, which suggests the existence of common etiological factors among these disorders. In this regard, genetic studies have identified a high number of loci consistently associated with T1D that also represent established genetic risk factors for other AIDs. In addition, studies focused on identifying the shared genetic component in autoimmunity have described several common susceptibility loci with a potential role in T1D. Elucidation of this genetic overlap has been useful in identifying key molecular pathways with a pathogenic role in multiple disorders. In this review, we summarize recent advances in understanding the shared genetic component between T1D and other AIDs and discuss how the identification of common pathogenic mechanisms can help in the development of new therapeutic approaches as well as in improving the use of existing drugs.

Discovery of Novel Host Molecular Factors Underlying HBV/HCV Infection.

Hepatitis is an inflammatory condition of the liver, which is frequently caused by the infection of hepatitis B virus (HBV) or hepatitis C virus (HCV). Hepatitis can lead to the development of chronic complications including cancer, making it a major public health burden. Co-infection of HBV and HCV can result in faster disease progression. Therefore, it is important to identify shared genetic susceptibility loci for HBV and HCV infection to further understand the underlying mechanism. Through a meta-analysis based on genome-wide association summary statistics of HBV and HCV infection, we found one novel locus in the Asian population and two novel loci in the European population. By functional annotation based on multi-omics data, we identified the likely target genes at each novel locus, such as HMGB1 and ATF3, which play a critical role in autophagy and immune response to virus. By re-analyzing a microarray dataset from Hmgb1–/– mice and RNA-seq data from mouse liver tissue overexpressing ATF3, we found that differential expression of autophagy and immune and metabolic gene pathways underlie these conditions. Our study reveals novel common susceptibility loci to HBV and HCV infection, supporting their role in linking autophagy signaling and immune response.

Abstract IA19: Genetic risk for subsequent breast cancer among female survivors of childhood cancer

Abstract Due to advancement in cancer therapy, greater than 80% of children diagnosed with cancer will survivor five or more years. It is estimated there are half a million childhood cancer survivors currently living in the US. Survivors are at increased risk of subsequent neoplasms, mostly considered therapy related. Breast cancer is one of the most common subsequent neoplasms among female survivors. It is known that radiation dose and volume to the breast is a major risk factor, leading to 20-fold increased risk with rate of cumulative incidence reaching 30% by age of 50 years. For non-irradiated survivors, literature also reported the risk of chemotherapy agents including anthracyclines. However, the genetic contribution was largely unknown before the groundbreaking genomic project was launched for the St. Jude Lifetime Cohort (SJLIFE) a few years ago. We analyzed the whole-genome sequencing data for 4402 survivors (2090 females, median age at follow up = 30 years, and median length of follow up = 22 years) from SJLIFE study. Pathogenic/likely (P/LP) variants were identified for 156 cancer predisposition genes and 127 DNA repair genes, respectively, with a small number of genes overlapped between the two gene sets. We also constructed a polygenic risk score based on 172 SNPs established from de novo breast cancer genetic association studies using the general population. Based on the multivariate piecewise exponential models, rate of subsequent breast cancer was significantly increased for female survivors who carried a P/LP variant in cancer predisposition genes and with or without chest irradiation. In addition, rate of subsequent breast cancer was significantly increased among all female survivors, especially survivors who carried a P/LP variant in homologous recombination DNA repair genes in conjunction with treatment exposures of chest irradiation (≥20Gy) and/or anthracyclines (doses in the second and third tertiles). Finally, we found survivors with high polygenic risk score had increased risk of developing subsequent breast cancer over and beyond the monogenic risk conferred by rare P/LP variants in breast cancer predisposition genes. Interestingly, African Americans seem to have the lowest prevalence of subsequent breast cancer among three different race groups: 1.3% for African Americans, 4.1% for European Americans and 5.9% for Asian/Native-Indian Americans. On the other hand, African Americans seem to have higher risk in developing subsequent breast cancer among carriers of P/LP variants compared to European Americans. We anticipate utilizing common susceptibility loci in combination with rare high-risk P/LP variants and other risk factors may inform a better strategy for breast cancer risk stratification among survivors of childhood cancer. Citation Format: Zhaoming Wang. Genetic risk for subsequent breast cancer among female survivors of childhood cancer [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr IA19.

Common susceptibility loci in both systemic sclerosis and localized scleroderma identified using genetic analysis.

Common susceptibility loci in both systemic sclerosis and localized scleroderma identified using genetic analysis.

Low-frequency variation near common germline susceptibility loci are associated with risk of Ewing sarcoma.

Ewing sarcoma (EwS) is a rare, aggressive solid tumor of childhood, adolescence and young adulthood associated with pathognomonic EWSR1-ETS fusion oncoproteins altering transcriptional regulation. Genome-wide association studies (GWAS) have identified 6 common germline susceptibility loci but have not investigated low-frequency inherited variants with minor allele frequencies below 5% due to limited genotyped cases of this rare tumor. We investigated the contribution of rare and low-frequency variation to EwS susceptibility in the largest EwS genome-wide association study to date (733 EwS cases and 1,346 unaffected controls of European ancestry). We identified two low-frequency variants, rs112837127 and rs2296730, on chromosome 20 that were associated with EwS risk (OR = 0.186 and 2.038, respectively; P-value < 5×10-8) and located near previously reported common susceptibility loci. After adjusting for the most associated common variant at the locus, only rs112837127 remained a statistically significant independent signal (OR = 0.200, P-value = 5.84×10-8). These findings suggest rare variation residing on common haplotypes are important contributors to EwS risk. Motivate future targeted sequencing studies for a comprehensive evaluation of low-frequency and rare variation around common EwS susceptibility loci.

LDtrait: An Online Tool for Identifying Published Phenotype Associations in Linkage Disequilibrium.

Genome-wide association studies (GWAS) have identified thousands of germline susceptibility loci associated with risk for cancer as well as a wide range of other traits and diseases. An interest of many investigators is identifying traits or diseases that share common susceptibility loci. We developed LDtrait (https://ldlink.nci.nih.gov/?tab=ldtrait) as an open access web tool for finding germline variation associated with multiple traits. LDtrait searches the NHGRI-EBI GWAS Catalog to identify susceptibility loci in linkage disequilibrium (LD) with a user-provided list of query variants. Options allow for modifying LD thresholds, calculating LD from a diverse set of reference populations, and downloading annotated variant lists. Results from example query searches highlight the utility of LDtrait in uncovering cross-trait associations for cancer risk and other traits. LDtrait accelerates etiologic understanding of cancer genetics by rapidly identifying genetic similarities with other traits or diseases. SIGNIFICANCE: The new GWAS search tool LDtrait will expedite discovery of shared genetic components underlying seemingly unrelated diseases and may offer novel insights into cancer research.

Abstract 4613: Cross-ancestry genome-wide association study identifies six new loci for breast cancer in women of African and european ancestry

Abstract Background: Over 180 genetic variants have been identified as risk loci for breast cancer. However, most loci were discovered using European ancestry populations. As some common susceptibility loci are shared across populations, we aim to discover new risk loci for breast cancer using a cross-ancestry genome-wide association study (GWAS) approach. Methods: Data from five GWAS studies in women of African ancestry with a combined sample size of 9241 cases and 10192 controls were used to generate pooled breast cancer risk estimates in a fixed effect meta-analysis, and this served as the discovery dataset. Summary statistics from the GWAS conducted in European ancestry populations (Breast Cancer Association Consortium, 122977 cases and 105974 controls) served as the validation dataset. The variants that were associated with breast cancer risk at P &amp;lt; 0.01 in the GWAS of African ancestry were meta-analyzed with the GWAS in European ancestry. A locus was considered novel if the lead index variant was genome-wide significant (5 × 10−8) in the cross-ancestry meta-analysis and &amp;gt;500kb away from known breast cancer risk loci. Conditional on the lead index variants, we searched for additional signals in each locus using multivariable logistic regression. Analyses were done separately for ER-positive, ER-negative and overall breast cancer risk. Results: We discovered four novel loci for overall breast cancer risk (1p13.3, 5q31.1, 15q24, and 15q26.3) and two novel loci for ER-negative breast cancer (1q41 and 7q11.23) at the genome-wide significance level of P &amp;lt; 5 × 10−8. Three index single nucleotide polymorphism (SNPs) lie within introns of genes (KCNK2, C5orf56, and SIN3A) and the other index SNPs are located in intergenic regions (close to GSTM4 and AMPD2, CASTOR2, and the antisense DNA RP11-168G16.2). The direction of the associations was consistent between the GWASs of African and European descendants. At the 15q24 locus, we found an additional SNP (in the intron of the SCAMP2 gene) to be independently associated with overall breast cancer risk. Conclusions: We have identified six new risk loci that may contribute to better prediction of breast cancer risk in African ancestry populations and provide new insights into mechanisms of breast cancer carcinogenesis. Replication of these loci in multiple populations and functional studies can help to identify causal variants. Citation Format: Babatunde Adedokun, Zhaohui Du, Guimin Gao, Thomas Ahearn, Kathryn L. Lunetta, Gary Zirpoli, Jonine Figueroa, Esther M. John, Leslie Bernstein, Wei Zheng, Jennifer J. Hu, Regina G. Ziegler, Sarah Nyante, Elisa V. Bandera, Sue A. Ingles, Michael F. Press, Sandra L. Deming, Jorge L. Rodriguez-Gil, Song Yao, Temidayo O. Ogundiran, Oladosu Ojengbede, William Blot, Melissa Troester, Katherine L. Nathanson, Anselm Hennis, Barbara Nemesure, Stefan Ambs, Lara E. Sucheston-Campbell, Jeannette T. Bensen, Stephen J. Chanock, Andrew F. Olshan, Christine B. Ambrosone, David V. Conti, Olufunmilayo I. Olopade, Montserrat Garcia-Closas, Julie R. Palmer, Christopher A. Haiman, Dezheng Huo. Cross-ancestry genome-wide association study identifies six new loci for breast cancer in women of African and european ancestry [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4613.

Common Susceptibility Loci for Male Breast Cancer.

BackgroundThe etiology of male breast cancer (MBC) is poorly understood. In particular, the extent to which the genetic basis of MBC differs from female breast cancer (FBC) is unknown. A previous genome-wide association study of MBC identified 2 predisposition loci for the disease, both of which were also associated with risk of FBC.MethodsWe performed genome-wide single nucleotide polymorphism genotyping of European ancestry MBC case subjects and controls in 3 stages. Associations between directly genotyped and imputed single nucleotide polymorphisms with MBC were assessed using fixed-effects meta-analysis of 1380 cases and 3620 controls. Replication genotyping of 810 cases and 1026 controls was used to validate variants with P values less than 1 × 10–06. Genetic correlation with FBC was evaluated using linkage disequilibrium score regression, by comprehensively examining the associations of published FBC risk loci with risk of MBC and by assessing associations between a FBC polygenic risk score and MBC. All statistical tests were 2-sided.ResultsThe genome-wide association study identified 3 novel MBC susceptibility loci that attained genome-wide statistical significance (P < 5 × 10–08). Genetic correlation analysis revealed a strong shared genetic basis with estrogen receptor–positive FBC. Men in the top quintile of genetic risk had a fourfold increased risk of breast cancer relative to those in the bottom quintile (odds ratio = 3.86, 95% confidence interval = 3.07 to 4.87, P = 2.08 × 10–30).ConclusionsThese findings advance our understanding of the genetic basis of MBC, providing support for an overlapping genetic etiology with FBC and identifying a fourfold high-risk group of susceptible men.

Family-based exome sequencing combined with linkage analyses identifies rare susceptibility variants of MUC4 for gastric cancer.

Genome-wide association studies of gastric cancer (GC) cases have revealed common gastric cancer susceptibility loci with low effect size. We investigated rare variants with high effect size via whole-exome sequencing (WES) of subjects with familial clustering of gastric cancer. WES of DNAs from the blood of 19 gastric cancer patients and 36 unaffected family members from 14 families with two or more gastric cancer patients were tested. Linkage analysis combined with association tests were performed using Pedigree Variant Annotation, Analysis, and Search Tool (pVAAST) software. Based on the logarithm of odds (LOD) and permutation-based composite likelihood ratio test (CLRT) from pVAAST, MUC4 was identified as a predisposing gene (LOD P-value = 1.9×10-5; permutation-based P-value of CLRT ≤ 9.9×10-9). In a larger cohort consisting of 597 GC patients and 9,759 healthy controls genotyped with SNP array, we discovered common variants in MUC4 regions (rs148735556, rs11717039, and rs547775645) significantly associated with GC supporting the association of MUC4 with gastric cancer. And the MUC4 variants were found in higher frequency in The Cancer Genome Atlas Study (TCGA) germline samples of patients with multiple cancer types. Immunohistochemistry indicated that MUC4 was downregulated in the noncancerous gastric mucosa of subjects with MUC4 germline missense variants, suggesting that loss of the protective function of MUC4 predisposes an individual to gastric cancer. Rare variants in MUC4 can be novel gastric cancer susceptibility loci in Koreans possessing the familial clustering of gastric cancer.

Common genetic susceptibility loci link PFAPA syndrome, Behçet's disease, and recurrent aphthous stomatitis.

Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is the most common periodic fever syndrome in children. The disease appears to cluster in families, but the pathogenesis is unknown. We queried two European-American cohorts and one Turkish cohort (total n = 231) of individuals with PFAPA for common variants previously associated with two other oropharyngeal ulcerative disorders, Behçet's disease and recurrent aphthous stomatitis. In a metaanalysis, we found that a variant upstream of IL12A (rs17753641) is strongly associated with PFAPA (OR 2.13, P = 6 × 10-9). We demonstrated that monocytes from individuals who are heterozygous or homozygous for this risk allele produce significantly higher levels of IL-12p70 upon IFN-γ and LPS stimulation than those from individuals without the risk allele. We also found that variants near STAT4, IL10, and CCR1-CCR3 were significant susceptibility loci for PFAPA, suggesting that the pathogenesis of PFAPA involves abnormal antigen-presenting cell function and T cell activity and polarization, thereby implicating both innate and adaptive immune responses at the oropharyngeal mucosa. Our results illustrate genetic similarities among recurrent aphthous stomatitis, PFAPA, and Behçet's disease, placing these disorders on a common spectrum, with recurrent aphthous stomatitis on the mild end, Behçet's disease on the severe end, and PFAPA intermediate. We propose naming these disorders Behçet's spectrum disorders to highlight their relationship. HLA alleles may be factors that influence phenotypes along this spectrum as we found new class I and II HLA associations for PFAPA distinct from Behçet's disease and recurrent aphthous stomatitis.

Abstract IA22: A comprehensive and integrated approach to identify factors associated with aggressive prostate cancer in African-Americans: The RESPOND Study

Abstract IA22: A comprehensive and integrated approach to identify factors associated with aggressive prostate cancer in African-Americans: The RESPOND Study