Pathogenic Mutations Research Articles

Cascade genetic testing: an underutilized pathway to equitable cancer care?

The Precision Medicine Initiative was launched upon the potential of genomic information to tailor medical care. Cascade genetic testing represents a powerful application of precision medicine and involves the process of familial diffusion or the "cascade" of genomic risk information. When an individual (proband) is found to carry a cancer-associated germline pathogenic mutation, the information should be cascaded or shared with at-risk relatives. First degree relatives have a 50% likelihood of carrying the same cancer-associated mutation. This process of cascade testing offers at-risk relatives the opportunity for genetic testing and, for those who also carry the cancer-associated mutation, genetically targeted primary disease prevention through intensive cancer surveillance, chemoprevention and risk-reducing surgery, reducing morbidity and preventing mortality. Cascade testing has been designated by the Centers for Disease Control and Prevention as a Tier 1 genomic application for hereditary breast and ovarian cancer. In this manuscript we describe a cascade genetic testing and in particular focus on its potential to provide necessary care to medically underserved and vulnerable populations.

Correlation of serum DKK1 level with skeletal phenotype in children with osteogenesis imperfecta.

We aim to detect serum DKK1 level of pediatric patients with OI and to analyze its relationship with the genotype and phenotype of OI patients. A cohort of pediatric OI patients and age-matched healthy children were enrolled. Serum levels of DKK1 and bone turnover biomarkers were measured by enzyme-linked immunosorbent assay. Bone mineral density (BMD) was measured by Dual-energy X-ray absorptiometry. Pathogenic mutations of OI were detected by next-generation sequencing and confirmed by Sanger sequencing. A total of 62 OI children with mean age of 9.50 (4.86, 12.00) years and 29 healthy children were included in this study. The serum DKK1 concentration in OI children was significantly higher than that in healthy children [5.20 (4.54, 6.32) and 4.08 (3.59, 4.92) ng/mL, P < 0.001]. The serum DKK1 concentration in OI children was negatively correlated with height (r = -0.282), height Z score (r = -0.292), ALP concentration (r = -0.304), lumbar BMD (r = -0.276), BMD Z score of the lumbar spine and femoral neck (r = -0.32; r = -0.27) (all P < 0.05). No significant difference in serum DKK1 concentration was found between OI patients with and without vertebral compression fractures. In patients with spinal deformity (22/62), serum DKK1 concentration was positively correlated with SDI (r = 0.480, P < 0.05). No significant correlation was observed between serum DKK1 concentration and the annual incidence of peripheral fractures, genotype and types of collagen changes in OI children. The serum DKK1 level was not only significantly elevated in OI children, but also closely correlated to their skeletal phenotype, suggesting that DKK1 may become a new biomarker and a potential therapeutic target of OI.

Detection of genetic mutations underlying early-onset systemic lupus erythematosus.

We aimed to investigate the presence of monogenic causes of systemic lupus erythematosus (SLE) in our early-onset SLE patients. Fifteen pediatric SLE cases who had early disease onset (≤6 years) were enrolled in this study. All patients fulfilled the Systemic Lupus International Collaborating Clinics (SLICC) criteria. Genomic DNA was used for whole exome sequencing (WES). Pathogenic variants were confirmed by Sanger sequencing. The median age at diagnosis of 15 early-onset SLE patients included in the study was 4 (2-6) years (F/M = 12/3). Significant gene mutations were detected in five of these patients (33.3%). Patients 1 and 2 with homozygous DNASE1L3 mutations [c.320+4_320+7del and G188A (c.563G>C) variants] had skin involvement and oral ulcers. One of them (patient 1) had arthritis and nephritis, and another (patient 2) had nonscarring alopecia and thrombocytopenia. They are currently clinically inactive but have positive serological findings. Patient 3 with homozygous pathogenic ACP5 mutation [G109R (c.325G>A) variant] had arthritis, nephritis, short stature, and skeletal dysplasia. Patient 4 with a heterozygote novel IFIH1 mutation [L809F (c.2425C>T) variant] had skin findings and leukopenia. Patient 5 with novel C1S variant [homozygous C147W (c.441C>G) variant] had marked skin findings, oral ulcers, nonscarring alopecia, pancytopenia, and low total hemolytic complement CH50 level. All patients have responded to the treatments and have low Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, on therapy. Genetic causes should be investigated in early-onset SLE, for better management and genetic counseling. On the other hand, multicenter studies may help to further define genotype-phenotype associations.

Clinical Case of Rare Genetic Disorder (Proud Syndrome) in a Child

Background. Proud syndrome is rare inherited disease with X-linked inheritance associated with mutations in the homeobox gene ARX. Typical clinical signs of this syndrome are severe mental retardation, intractable epilepsy, agenesis (dysgenesis) of corpus callosum. Less common features are genital abnormalities, microcephaly, facial dysmorphia, and skeletal malformations. Clinical case description. The article describes the clinical findings of Proud syndrome in girl A., admitted to Children’s City Clinical Hospital No. 1 in Nizhny Novgorod. The girl was born without asphyxia at term through natural vaginal delivery after the first uneventful pregnancy. Body weight at birth was 2600 g. The genealogical history is burdened by the presence of epilepsy in girl’s father relatives. There were no deviations in psychomotor skills development before disease onset. Hemi-convulsive seizures (switching sides) have appeared at the age of 6 months. These attacks had status course and were resistant to anticonvulsant therapy. Neuroimaging has revealed agenesis of corpus callosum. Regression of psychomotor development, new behavioral disorders (stereotypes and auto-aggression), hyperexcitability, and sleep disorders were observed in dynamics. The diagnosis of Proud syndrome was confirmed by identification of probably pathogenic mutation in the ARX gene (c.1111C&gt;T, p. Arg 371*64). The features of anticonvulsant management were demonstrated in the patient. Conclusion. This clinical case presents typical clinical picture of Proud syndrome. The disease is non-curable. Such patients should be administered with syndromic therapy: constant anticonvulsant therapy, correction of behavioral disorders (classes with specialist on mental defects), neurologist, epileptologist, psychiatrist observations. Parental examination is crucial ARX mutation search in order to determine the prognosis for further child-bearing (parents refused to perform genetic study at the time of article writing).

Unveiling a novel GJB2 dominant K22T mutation in a Chinese family with hearing loss.

Hearing loss constitutes one of the most prevalent conditions within the field of otolaryngology. Recent investigations have revealed that mutations in deafness-associated genes, including point mutations and variations in DNA sequences, can cause hearing impairments. With the ethology of deafness remaining unclear for a substantial portion of the affected population, further screenings for pathogenic mutations are imperative to unveil the underlying mechanisms. On this study, by using next-generation sequencing, we examine 129 commonly implicated deafness-related genes in a Chinese family with hearing loss, revealing a novel heterozygous dominant mutation in the GJB2 gene (GJB2: c.65T>G: p. Lys22Thr). This mutation consistently occurs in affected family members but is not detected in unaffected individuals, strongly suggesting its causative role in hearing loss. Structural analysis indicates potential disruption to the Cx26 gap junction channel's hydrogen bond and electrostatic interactions, aligning with predictions from the PolyPhen and SIFT algorithms. In conclusion, our study provides conclusive evidence that the identified heterozygous GJB2 mutation (GJB2: c.65T>G: p. Lys22Thr), specifically the K22T alteration, is the primary determinant of the family's deafness. This contribution enhances our understanding of the interplay between common deafness-associated genes and hearing loss, offering valuable insights for diagnostic guidance and the formulation of therapeutic strategies for this condition.

Li-Fraumeni Syndrome With Six Primary Tumors—Case Report

Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome associated with a high, lifetime risk of a broad spectrum of cancers caused by pathogenic germline TP53 mutations. Numerous different germline TP53 mutations have been associated with LFS, which has an exceptionally diverse clinical spectrum in terms of tumor type and age of onset. Our patient has developed six asynchronous tumors to date: a phyllode tumor of the breast, a pheochromocytoma, a rosette-forming glioneuronal tumor (RGNT), an adrenocortical carcinoma (ACC), a ductal carcinoma of the breast, and a thymoma. The occurrence of such a number of rare tumors is sporadic even among in the population of patients living with cancer predisposition syndromes. In this instance, the omission of pretest genetic counseling and thorough family tree analysis prior to selecting the test led to the oversight of an underlying TP53 likely pathogenic mutation (classified as Class 4). This emphasizes the necessity for such counseling to prevent overlooking crucial genetic information. Neglecting this step could have had profound implications on the patient’s treatment, particularly considering the early onset and occurrence of multiple tumors, which typically raise suspicion of a hereditary component. The implications for family members must be considered.

Columnar Cell Thyroid Carcinoma: A Heterogeneous Entity Demonstrating Overlap Between Papillary Thyroid Carcinoma and Follicular Neoplasms.

Columnar cell papillary thyroid carcinoma (CC-PTC) is a morphologic subtype of papillary thyroid carcinoma with a variable prognosis. It is characterized by neoplastic thyroid follicular-derived cells with pseudostratified columnar morphology arranged in papillary or follicular structures with supranuclear or subnuclear vacuoles. The molecular profile of this subtype has only recently come under scrutiny, with mixed results. The aim of this study is to further explore the morphologic, immunohistochemical, and genetic profile of CC-PTC, as well as to correlate these features with clinical outcomes. CC-PTC cases were identified from 3 institutions. Immunohistochemistry (ER, CDX2) and molecular testing (DNA and RNA sequencing) were performed. Clinicopathologic parameters and patient outcomes were recorded. Twelve cases (2006-2023) were identified, all in adults (age 45-91). Two presented with disease outside the thyroid gland (neck and mediastinum) and two presented with distant metastasis. Four were high-grade differentiated thyroid carcinomas (necrosis or mitoses), one of which died of disease. Four were noninvasive or minimally invasive, one of which locally recurred. Three patients had lymph node metastases. ER and CDX2 were positive in 73% and 50%, respectively. Pathogenic mutations were found in TERT promoter (n = 3), RAS (n = 2), ATM, NOTCH1, APC, and ESR1, along with cases bearing AGK::BRAF fusion (n = 1), BRAF VE1 expression (n = 1), and NF2 loss (n = 1). This study represents the largest molecularly defined cohort of non-oncocytic thyroid carcinomas with columnar cell morphology. These tumors represent a genetically and behaviorally heterogeneous group of neoplasms, some of which have RAS-like or follicular neoplasm-like genetics, some of which have BRAF-p.V600E-like or classic papillary thyroid carcinoma-like genetics, and some of which remain unclear. Noninvasive or minimally invasive tumors showed an indolent course compared to those with angioinvasion, gross extrathyroidal growth, or high-grade morphology. Consideration could be given to reclassification of this neoplasm outside of the subtyping of papillary thyroid carcinoma in light of its genetic diversity, distinct morphology, and clinical behavior more closely aligned with follicular thyroid neoplasms.

Diagnosis of Fabry Disease Using Alpha-Galactosidase A Activity or LysoGb3 in Blood Fails to Identify Up to Two Thirds of Female Patients

Anderson–Fabry disease is a lysosomal storage disorder caused by mutations in the GLA gene, which encodes the enzyme α-galactosidase A. The GLA gene is located on the X-chromosome, causing an X-linked pathology: due to lyonization, female patients usually manifest a variable symptomatology, ranging from asymptomatic to severe phenotypes. The confirmation of the clinical diagnosis of Fabry disease, achieved by measuring α-galactosidase A activity, which is usually the first test used, shows differences between male and female patients. This assay is reliable in male patients with causative mutations in the GLA gene, in whom the enzymatic activity is lower than normal values; on the other hand, in female Fabry patients, the enzymatic activity is extremely variable between normal and pathological values. These fluctuations are also found in female patients’ blood levels of globotriaosylsphingosine (LysoGb3) for the same reason. In this paper, we present a retrospective study conducted in our laboratories on 827 Fabry patients with causative mutations in the GLA gene. Our results show that 100% of male patients had α-galactosidase A activity below the reference value, while more than 70% of female patients had normal values. It can also be observed that almost half of the female patients with pathogenic mutations in the GLA gene showed normal values of LysoGb3 in blood. Furthermore, in women, blood LysoGb3 values can vary over time, as we show in a clinical case presented in this paper. Both these tests could lead to missed diagnoses of Fabry disease in female patients, so the analysis of the GLA gene represents the main diagnostic test for Fabry disease in women to date.

Epidemiology of rotavirus infection: the evolution of the pathogen and the success of vaccination

The review presents data on the spread of various rotavirus genotypes and its variability in the world and in Russia, which occur both due to natural causes and under the influence of vaccination against rotavirus infection, as well as on the transformation of clinical and epidemiological features of the course of this disease in children as a result of the pathogen mutations.

Outcomes of a universal germline screening program in a community urology practice.

The role of germline genetic testing in urologic oncology has expanded in recent years. However, implementation of genetic testing in community practices remains a challenge, often due to limited access to qualified genetics trained providers. In this study, we report outcomes of a universal germline screening program in a community urology practice. Between November 2021 and September 2022, all patients referred for urology clinic visits at Frederick Health (Frederick, MD, USA) were provided an online genetics screening questionnaire prior to the visit. Responses were compared against National Comprehensive Cancer Network (NCCN) criteria for germline testing. Those who met criteria were provided educational materials at the end of the questionnaire, and then counseled by a trained urologic oncologist (HC) in the clinic or referred to a genetic counselor prior to testing. Testing was performed with a 36-gene pan-cancer panel (CancerNext) or a 14-gene targeted prostate cancer panel (ProstateNext), with or without additional RNA analysis (RNAinsight) (Ambry Genetics, CA, USA). Demographic and clinical parameters, as well as genetic testing results, were retrospectively collected under IRB approval. In the study period, 765 patients were seen over 1370 clinic visits. Of these, 505 patients (66.0%) completed the screening questionnaire. The majority were completed via email (54.5%) with the remainder (45.5%) via text message. Of the patients who completed screening, 125/505 (24.7%) met NCCN criteria for germline testing. 58/125 patients (46.4%) who met criteria underwent germline testing, of whom 5/58 (8.6%) had distinct pathogenic mutations identified. These included actionable mutations in BRCA1, BRCA2, and CHEK2, as well as an additional pathogenic mutation in NBN. Variants of unknown significance were identified in 8/58 patients (13.8%) in 11 total genes. Challenges to implementation of this program included meeting institutional requirements for genetic testing consent, facilitating specimen collection in clinic, and integration of results into the electronic health record. Genetic risk assessment for high-risk individuals is feasible as part of a universal screening program in a community urology practice. Approximately 8% of tested patients were found to have pathogenic germline mutations, which is consistent with contemporary tertiary referral cohorts.

Abstract PO4-08-10: Genetic mutations and associated rates of pathologic complete response among a diverse patient population with early stage triple negative breast cancer

Abstract Background: Combination treatment with chemotherapy and immunotherapy remains the standard of care for high risk, early-stage triple negative breast cancer (TNBC). Although the addition of immunotherapy improves rates of pathologic complete response (pCR) and event-free survival, approximately 50% of patients achieve pCR with neoadjuvant chemotherapy alone suggesting that some patients may safely avoid the potential toxicities of immunotherapy without compromising outcomes.1,2 Markers of immune activation including PD-L1 expression and tumor infiltrating lymphocytes have demonstrated prognostic significance; however, identifying a predictive biomarker to aid in selecting those patients most likely to benefit from immunotherapy remains an unmet need.3,4 Genetic mutations are suggestive of DNA susceptibility to damage and the role they may play as a potential marker of immune response is unclear.5,6 This study explores genetic analysis and mutation rates among a diverse cohort of patients with TNBC to identify patterns associated with and without pCR. Methods: We evaluated 105 women diagnosed with Stage I-III TNBC and treated with combination neoadjuvant chemotherapy and immunotherapy at Ochsner Cancer Center between December 2019 through June 2022. Exclusion criteria included ER+, PR+, HER2+, or unknown receptor status, no pembrolizumab in the neoadjuvant setting, no definitive surgery following neoadjuvant treatment, absence of documented race and age less than 18 years of age. Data was collected utilizing Epic Slicer Dicer program, in addition to chart review. Genetic analysis was performed using a variety of DNA-based next generation sequencing analysis platforms. Results: 91 patients met inclusion criteria. 17 patients were found to have pathogenic mutations (BRCA1/2, POLE and ATM), 38 patients had variants of undetermined significance (VUS) and 36 patients had neither. Among patients with pathogenic genetic mutations, 81.25% had a pCR following neoadjuvant treatment compared to 58.33% of those with a VUS and 47.06% of those with no known mutation (p=0.07). Before adjusting for age and stage, patients with a pathogenic mutation were 73% more likely to achieve pCR than those with no known genetic mutations (crude RR: 1.73, 95% CI: 1.13-2.65). After adjusting for age and stage, the relationship was not statistically significant (aRR: 1.15, 95% CI: 0.78-1.34). Among the 47 Black patients, 5 were found to have a pathogenic mutation and 29 had a VUS. 11 of the 39 White patients were found to have a pathogenic mutation while only 6 had a VUS. Across all genetic mutation categories, Black patients experienced lower rates of pCR than White patients. White patients with a known pathogenic mutation had the highest rate of pCR at 90.91%, while Black patients with no identified mutation had the lowest rate of pCR at 38.46%. The generalizability of these results may be limited due to small sample size. Conclusion: Our results demonstrating higher rates of genetic variants among patients achieving pCR regardless of race highlight the importance of better understanding how these variants correlate with tumor mutational burden (TMB) and further, the role this may play in predicting immune-response. Larger studies are needed to assess TMB as a predictive biomarker in early-stage TNBC as this may provide opportunities to further individualize treatment and minimize toxicity among this group of patients. Additionally, given differences in the prevalence of pathogenic mutations and VUS among Black patients, better understanding the relationship between mutation status and immune response is imperative to optimize outcomes in this high-risk population. Table. Citation Format: Caitlin Taylor, Melanie Sheen, Rabia Cattie, Victoria Chung, Melyssa Bratton, Meredith Lakey, Erin Biggs. Genetic mutations and associated rates of pathologic complete response among a diverse patient population with early stage triple negative breast cancer [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 PO4-08-10.

Abstract PO4-19-08: Randomized phase II study of talazoparib vs talazoparib plus atezolizumab for patients with premenopausal HR+/HER2- metastatic breast cancer harboring homologous recombination deficiency scar (Young-PALETTA, KCSG BR21-09)

Abstract Background Cyclin D kinase-4/6(CDK4/6) inhibitor combined with endocrine treatment have significantly increased progression free survival(PFS) and overall survival(OS) of patients with hormone receptor(HR)-positive/HER2-negative metastatic breast cancer, and currently is a standard 1st line endocrine treatment option. Homologous recombination deficiency(HRD) including germline(g) BRCA1/2 pathogenic mutation is known to be prevalent among young premenopausal patients. Recently several retrospective data suggested that patients with germline BRCA1/2 pathogenic mutation or HRD have poorer outcome with CDK4/6 inhibitor treatment, however there is no prospective evidence. Poly ADP-ribose polymerase(PARP) inhibitors have shown significant benefit over standard chemotherapy in patients with HER2-neg metastatic breast cancer and gBRCA1/2 pathogenic mutation in two Phase 3 trials. Since preclinical data suggested that PARP inhibitors play a role in anti-tumor immune modulation, immunotherapy combined with PARP inhibitors were explored and showed promising antitumor efficacy in several single arm trials. In this trial, we investigate talazoparib and atezolizumab combination compared with talazoparib monotherapy in premenopausal women with HR+/HER2- metastatic breast cancer with HRD-scar after failure with 1st line palbociclib and endocrine treatment combination. Methods This study is a multicenter, randomized, open-label phase II trial comparing talazoparib versus talazoparib with atezolizumab in premenopausal women with HR+/HER2- metastatic breast cancer harboring HRD scar whose disease have progressed with endocrine and palbociclib combination as the 1st-line endocrine treatment. Prior one line of cytotoxic chemotherapy other than platinum for metastatic setting is allowed, but prior palliative endocrine treatment is not allowed. Eligible patients will be pre-screened with tumor tissue biopsy and peripheral blood sampling before endocrine and palbociclib treatment commencement. HRD status is determined through targeted sequencing(SOLIDaccuTestTM by NGeneBio) of tumor tissue and germline HRD genes including BRCA1/2 variant test. Whole genome sequencing and RNA sequencing are performed for biomarker analyses. Patients harboring HRD scar will receive first line endocrine treatment with palbociclib plus aromatase inhibitor with ovarian suppression. After progression with 1L endocrine treatment, patients will be randomized to either talazoparib alone or talazoparib plus atezolizumab combination. Germline BRCA1/2 pathogenic mutation is a stratification factor. Primary endpoint is a progression free survival after randomization(PFS2). Secondary objectives are a composite of PFS1 and PFS2, PFS1, overall survival, patient reported outcome, and biomarkers for treatment response. A total of 178 subjects are required to detect hazard ratio of 0.62 (median PFS2 of at least 10.5 months with talazoparib and atezolizumab combination vs 6.5 months with talazoparib alone), to achieve 80% power at a two-sided a significance level at 10%, considering drop-out rate of 5%. The study period is expected to be 72 months overall(36 months for accrual and randomization and 24 months of follow-up for primary endpoint PFS2). Citation Format: Hee Kyung Ahn, Jieun Lee, Jee Hung Kim, Kyung-Hun Lee, Jee Hyun Kim, Min Hwan Kim, Minsuk Kwon, Han Jo Kim, Kyung Hae Jung, Yeon Hee Park. Randomized phase II study of talazoparib vs talazoparib plus atezolizumab for patients with premenopausal HR+/HER2- metastatic breast cancer harboring homologous recombination deficiency scar (Young-PALETTA, KCSG BR21-09) [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 PO4-19-08.

Abstract PO1-09-03: Clinical Impact of Multigene Panel Testing in Patients with a Personal or Family History of Breast or Ovarian Cancer Previously Negative for BRCA1/2 Genes

Abstract Rapid developments in cancer genetics and hereditary cancer risk assessments have enabled the identification of individuals at elevated risk for hereditary malignancies to guide enhanced cancer screening and prevention efforts. Multigene panel testing has emerged as the standard approach as emphasized in the National Comprehensive Cancer Network (NCCN) guidelines. The purpose of this study was to investigate the frequency of other pathogenic mutations identified through multigene panel testing in individuals who previously tested negative for germline BRCA1/2 and assess the clinical impact of panel testing. Patients either previously diagnosed with breast cancer or with a family history of breast or ovarian cancer that had also been seen by Oncology Genetics at a single institution and tested negative for BRCA1/2 genes but had not undergone prior multigene panel testing were invited via a letter to return for an additional genetic counseling visit to discuss multigene panel testing. Patients were also able to opt-in to a survey component of the study and received an email to fill out the Multidimensional Impact of Cancer Risk Assessment (MICRA) and Cancer Worry Scale (CWS). Surveys were completed prior to the initial genetic counseling appointment and repeated after discussion of the multigene panel test results. A total 24 women met with a genetic counselor of which 22 (92%) had a personal history of breast cancer, 1 (4%) had a family history of breast cancer, and 1 (4%) had a family history of ovarian cancer. The mean age was 52.6 years (range, 42-68) and 100% of women were Caucasian. Of the 24 women, 17 (71%) completed multigene panel testing. Of the women that underwent testing, 7 (41%) had negative results, 6 (35%) had variants of unknown significance (VUS), and 4 (24%) had a pathogenic mutation identified in another gene (CDKN2A, CHEK2, and CFTR). There was no significant change in MICRA or CWS scores after multigene panel results were reviewed in the 9 patients that completed both pre- and post-genetic testing surveys. The mean/median summary MICRA scores pre- and post-counselling were 30 (SD 12.4), median 26 (min 18, max 56), and 21.2 (SD 15.4), median 21 (min 3, max 43), respectively (p=0.19, Wilcoxon signed ranks test). The mean/median summary CWS scores pre- and post-counselling were 14.3 (SD 5), median 15 (min 7, max 24), and 13.6 (SD 2.59), median 14 (min 10, max 17), respectively (p=0.53, Wilcoxon signed ranks test). Of the 4 patients with newly identified pathogenic mutations, 2 started new screening protocols and 1 underwent a prophylactic mastectomy. In conclusion, multigene panel testing identified pathogenic mutations in a subset of individuals who previously tested negative for BRCA1/2 genes leading to changes in clinical management. The completion of multigene panel testing did not lead to a significant increase in MICRA or CWS scores. Key limitations of this study include a small sample size and an all Caucasian population. Citation Format: Devon Miller, Stephanie Pritzl, Angela Tess, Jessica Gooding, Lisa Barroilhet, Lori Dubenske, Kari Wisinski. Clinical Impact of Multigene Panel Testing in Patients with a Personal or Family History of Breast or Ovarian Cancer Previously Negative for BRCA1/2 Genes [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 PO1-09-03.

Abstract PO1-20-01: A Prospective Single-Arm Pilot Interventional Trial to Assess Individual Breast Cancer Risk Prior to Gender-Affirming Chest Masculinization Surgery

Abstract Background: The number of individuals who identify as transgender and/or gender-diverse (TGD) is steadily increasing and the number of individuals seeking chest masculinization surgery, commonly called “top-surgery,” is also increasing. In persons assigned female at birth, top surgery removes most breast tissue to allow the chest to appear masculine. However, top surgery is not equivalent to oncologic risk-reducing mastectomies (RRM), which aim to remove all breast tissue to reduce future breast cancer (BC) risk. While top surgery has significant psychological and health benefits, its impact on future BC risk is unclear, especially for those individuals who are at high-risk for future BC development (defined as ≥17% by international consensus guidelines) and/or have a pathogenic germline mutation for BC. The aims of this study are to 1) determine the percentage of TGD persons assigned female at birth who are considering undergoing top surgery and are at elevated BC risk using validated risk models, 2) determine the percentage of TGD persons at elevated BC risk who choose to undergo RRM as part of top surgery, and 3) assess and compare self-perceived BC risk compared to calculated risk. Methods: A single-institution prospective single-arm pilot study is currently underway from March 2023 through January 2024. Individuals assigned female at birth, who are age ≥18 years, and considering undergoing top surgery, but have not yet undergone top surgery, are eligible to enroll (goal accrual N=35). Participants are being actively recruited form our institution’s Comprehensive LGBTQIA+ Inclusion Health Clinic and Plastic Surgery Clinic. Consented participants undergo a personalized BC risk assessment the validated IBIS and Gail (for those ≥35 years old) BC risk models. Those with an average lifetime BC risk (&amp;lt; 17%) are recommended to continue top surgery as planned/no intervention, participants with a moderate lifetime BC risk (17-30%) are counseled they may consider RRM as part of their top surgery operation given that sparse data exists in this space, while those with a high lifetime BC risk ( &amp;gt;30% or pathogenic germline variant) are counseled on the potential benefits of RRM. Participants with a family history suggestive of a hereditary cancer syndrome meet with a certified Genetics counselor for consideration of genetic testing, per NCCN guidelines. Results: We anticipate reporting 1) general demographic description of the cohort, 2) the percentage who have an elevated lifetime BC risk and/or a pathogenic genetic mutation, 3) the percentage of those with an elevated risk who choose to undergo RRM as part of top surgery, and 4) report the differences between self-perceived vs calculated lifetime BC risk. Conclusion: Our findings will inform TGD persons and surgeons on the utility of a personalized BC risk assessment prior to top surgery to assist in surgical decision-making, report the accuracy of self-perceived BC risk in TGD persons, and potentially change the standard pre-operative evaluation for TGD persons considering top surgery to include a formal BC risk assessment to ensure high-risk individuals have the option to undergo RRM to appropriately reduce their future BC risk. Citation Format: Chandler Cortina, Anna Purdy, Samantha Stachowiak, Kristen Klement, Sarah Sasor, Kate Krucoff, Andrew Petroll, Kevin Robertson, Annie Lakatos, Erin Doren. A Prospective Single-Arm Pilot Interventional Trial to Assess Individual Breast Cancer Risk Prior to Gender-Affirming Chest Masculinization Surgery [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 PO1-20-01.

Abstract PO1-22-03: Radiation Toxicity and Treatment Outcomes in Breast Cancer Patients with ATM Pathogenic and VUS Mutations: Implications for Personalized Therapy

Abstract Introduction: Previous studies have shown that ATM (ataxia-telangiectasia mutated) mutations may be associated with increased radiation sensitivity and altered treatment response. However, there is a limited understanding of the clinical implications and optimal management strategies for breast cancer patients with ATM mutations receiving radiotherapy (RT). The aim of our study is to assess the impact of ATM mutations on radiation response and treatment outcomes in breast cancer patients undergoing RT. Material and Methods: A total of 79 female patients diagnosed with breast cancer were included in the study, with 31 (39.3%) having pathogenic (P) and likely pathogenic (LP) variants (all of the variants were heterozygous) and 48 (60.8%) having VUS variants detected through whole ATM gene sequencing screening for patients in accordance with NCCN clinical practice guideline. Statistical analysis, including descriptive, graphical, and inferential methods, such as the Kolmogorov-Smirnov test, Mann-Whitney U Test, and Chi-square tests, was conducted using SPSS version 25.0 to evaluate the normal distribution of continuous variable scores and perform quantitative and qualitative comparisons between groups at a 95% confidence level (p &amp;lt; 0.05). Results: The median age of the patients was 44 years (range: 24-74), with 75% of them being 50 years old or younger .The rate of breast cancer in patients with VUS variants was significantly higher in those aged 50 and below compared to those with P/LP variants (83% vs. 61%, p=0.028). There was no statistically significant difference in clinical stage, tumour histological type, and molecular subtype classification based on ATM gene variant type (P/LP vs. VUS) among the patients (p&amp;gt;0.05), but the rate of high tumour grade was significantly higher in the VUS variant group (65% vs. 40%, p=0.034). The rate of patients who received RT was 87%, with 26 patients receiving radiation to the breast or chest wall and 43 patients receiving additional regional lymph node irradiation. There were no statistically significant differences in surgical and systemic treatment types and RT dose based on ATM gene variant type (P/LP vs. VUS) (p&amp;gt;0.05). Among the patients who received RT, 33 (48%) experienced early-stage skin reactions, and 15 (22%) experienced late-stage skin reactions according to Common Terminology Criteria for Adverse Events (CTCAE) v5. No Grade 3, 4 and 5 early and late toxicity were observed . The rate of early (83% vs. 23%; p&amp;lt; 0.001) and late (35% vs. 13%; p=0.029) skin reactions was significantly higher in the P/LP variant group compared to the VUS variant group. Grade I lymphedema was observed in 2 (2.5%) patients, 1 (3.2%) in the P/LP group and 1 (2.1%) in the VUS group (p&amp;gt;0.05). Among the 23 patients who underwent breast reconstruction, 1 (4%) had implant revision and 1 (4%) experienced implant loss, both of which were observed in the pathogenic variant group (p&amp;gt;0.05). Conclusion: Limited clinical data exists on RT toxicity in breast cancer patients with ATM gene mutations, and clear guidelines for decision-making are lacking. Our study revealed higher rates of acute and chronic skin reactions in the P/LP variant group, highlighting the need for further investigation into the impact of these variants on treatment outcomes and patient management. However, it is crucial to manage these reactions effectively and not allow them to hinder treatment. Additional research and interventions are warranted to better understand and address these reactions, aiming to enhance the overall treatment experience and outcomes for patients with ATM gene mutations. Citation Format: Evrim Tezcanli, Seda Eroz, Ugur Ozbek, Ahmet Yesilyurt, CIHAN URAS, Nuran Bese. Radiation Toxicity and Treatment Outcomes in Breast Cancer Patients with ATM Pathogenic and VUS Mutations: Implications for Personalized Therapy [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 PO1-22-03.

Abstract PO5-23-05: The Impact of Bi-Annual Diagnostic Imaging on Detecting Ipsilateral Breast Recurrence in Patients Undergoing Breast Conserving Surgery for Breast Cancer

Abstract Introduction: Breast conserving surgery (BCS) represents the preferred option for surgical treatment for a majority of patients with early-stage breast cancer who are eligible for this approach. When compared with mastectomy approaches, BCS provides patients with equivalent survival while preserving the affected breast. It is necessary to achieve clear surgical margins as positive lumpectomy margins are associated with an increased risk for ipsilateral breast tumor recurrence. With advances in imaging techniques, as well as effective systemic therapy and contemporary radiation therapy, local recurrence after BCS has decreased and overall survival for patients has improved. Retrospective studies have quantified the recurrence rate in unifocal breast cancer as 8 - 15% at 20 years. The NCCN recommends annual mammography at least 6 months after post-lumpectomy radiation therapy, but there is little data regarding more frequent surveillance after lumpectomy in the early post-operative setting. The purpose of this study was to evaluate the impact of short interval surveillance mammography on the detection of early in-breast recurrence in patients undergoing BCS. Methods: Our IRB-approved Breast Cancer Database was queried for patients enrolled from 11/2009 to 6/2023 who underwent breast conservation surgery for a diagnosis of in situ or invasive breast cancer in this retrospective analysis. Per our institutional protocol, patients were recommended to undergo diagnostic mammography of the treated breast(s) every 6 months for 2 years after BCS. After the initial 2 year period, bilateral mammography was performed annually in the absence of other indications. Additional supplemental imaging such as breast ultrasound and MRI were performed at physician discretion and based on patient risk and breast density. Variables of interest included the presence of pathogenic germline mutations, family history of breast cancer, and disease characteristics. Our primary endpoint was ipsilateral breast tumor recurrence. Results: Of 2491 patients who underwent breast conservation surgery for in situ or invasive breast cancer, 191 (7.7%) developed recurrent disease, including ipsilateral and contralateral recurrence, and distant disease, in the study period. A total of 83 (3.2%) patients developed ipsilateral breast recurrence during the entire study period. Of those, 19 (22.9%) were detected within the first two years after surgery. Six of the 19 patients (31.6%) had their recurrences detected on yearly diagnostic mammography while 6 (31.6%) patients had their recurrences detected on interval 6-month unilateral diagnostic imaging. In both groups, 5/6 recurrences were invasive disease after an original diagnosis of invasive cancer, and the remaining patient had recurrent DCIS. The remaining 7/19 patients (36.8%) had their ipsilateral recurrences detected on palpation or other diagnostic imaging. In this group as well, there was one case of recurrent DCIS, with the remaining 6 cases representing recurrent invasive cancer. Of the 19 patients with ipsilateral recurrences, none had pathogenic germline mutations. 4 of the 19 patients (21%) had positive margins after their initial lumpectomy surgery with re- excisions required to achieve clear margins. Conclusion: Interval diagnostic surveillance imaging every 6 months after breast conserving surgery identified almost one-third of the ipsilateral breast tumor recurrences that occurred within the first 2 years after surgery in our population. While our numbers are small, the relationship of re-excision lumpectomy surgery to subsequent risk for local recurrence has been described by others, and bears further study. Particularly in view of our observation that the majority of in-breast recurrences were invasive, our data supports the practice of more frequent imaging follow up in the first 2 years after breast conserving surgery. Citation Format: Pabel Miah, Laura Fiedler, Anthony Baez, Athanasios Sevdalis, Alyssa Marmer, Charles DiMaggio, Linda Pak, Richard Shapiro, Karen Hiotis, Deborah Axelrod, Amber Guth, Freya Schnabel. The Impact of Bi-Annual Diagnostic Imaging on Detecting Ipsilateral Breast Recurrence in Patients Undergoing Breast Conserving Surgery for Breast Cancer [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 PO5-23-05.

Abstract PO1-08-11: The survival rate of hereditary breast cancer in young women of Kazakh population

Abstract Background The study focused on determining survival rates between breast cancer patients with various germinal mutations and those without mutations among Kazakh women. Methods The study included 222 female patients of Kazakh ethnic group diagnosed with stage I-IV stage breast cancer at the age up to 40 years old. DNA samples were tested by next-generation sequencing on the MiSeq Illumina platform using Trusight Cancer kit for the analysis of 94 genes and 287SNPs. Information about dates of diagnosis and death retried from cancer registry system. Survival analyses were performed and compared mutation carriers and non-carriers subgroups. The 5-year survival was calculated using the Kaplan-Meier method. Results Next generation sequencing test identified 11 various pathogenic mutations in 57(25.7%) of overall 222 patients. The 5-year survival analysis for mutation carriers were 72.1%and 82.1% for non-carriers, with no statistically significant difference(P0.232). When stratified by mutational type, the 5-year survival rates were 71.8% for BRCA1 carriers, 81.3% for BRCA2, 53.35% for TP53 and 50% for moderate risk gene PALB2 mutation. These findings suggest that mutations in certain genes may be associated with differences in survival outcomes. Conclusions In breast cancer patients of Kazakh population similar to the world prevalence and predictive value of germline mutations have been found. A subcohort of mutation carriers and non-carriers demonstrated no significant difference in 5-year survival rate which may be associated with an early onset of disease, high-risk predictor of poor prognosis. Long-term survival and detailed PFS will be published according to information of follow-up visits and the cancer register system. Citation Format: Dilyara Kaidarova, Nazgul Omarbayeva, Aliya Abdrakhmanova, Oxana Shatkovskaya, Dilyar Omarov. The survival rate of hereditary breast cancer in young women of Kazakh population [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 PO1-08-11.

Abstract PO1-14-08: Real-world clinical genomics study of HR+/HER2- metastatic breast cancers treated by CDK4/6i plus endocrine therapies revealed a drug resistant tumor segment characterized by ER independence

Abstract Background CDK4/6 inhibitors (CDK4/6i) plus endocrine therapies (ET) are the standard-of-care for hormone receptor–positive/human epidermal receptor 2–negative metastatic breast cancer (HR+/HER2− mBC). However, drug resistance remains a major unmet need. Investigations of drug resistance mechanisms has been hampered by a dearth of tumor molecular profiling data from the post-treatment setting. To address this challenge, we have conducted a real-world clinical genomics study to better understand the molecular mechanism of CDK4/6i resistance as well as to stratify patients based on integrated multi-omics profiles. Methods We retrospectively analyzed a multi-omics dataset of 400 HR+/HER2- mBC patients who had received CDK4/6i plus ET and developed progressive disease (PD) from the de-identified Tempus database. Pre-treatment and post-progression biopsies were taken  1 year prior to starting the CDK4/6i treatment or following PD respectively. Tempus xT next-generation sequencing (DNA-seq of 648 genes) and RNA sequencing assays were performed on 427 tumor FFPE samples, including 200 pre-treatment, 227 post-progression and 26 longitudinal pairs. Results The median age of the patients was 57 (54.9-57.4) and median progression free survival (PFS) is 379 (341-433) days. Two genes were found to harbor a significant increase in genomic alteration frequencies (GAF) after adjusting for FDR at post-progression vs. pre-treatment – ESR1 (41.9% vs. 15%, p=5.4e-10), RB1 (13.2% vs. 3%, p=8.5e-05). ESR1 and RB1 also harbored high frequencies of acquired genomic alterations among 26 paired samples at 34.6% and 11.5% respectively. TP53 mutation at baseline was significantly associated with shorter PFS at baseline (p=4.23e-05, HR=2.081) and TP53 GAF significantly increased after PD (37% vs. 28.5%, p=0.039). BRCA1/2 pathogenic mutations (p=1.63e-04, HR=3.066), APOBEC mutation signature S13 (p=0.0125, HR=1.55) and CCNE1 gene expression (p=0.024, HR=1.46) were significantly associated with shorter PFS. APOBEC signature (p=0.0035) and CCNE1 expression (p=1.33e-06) also significantly increased post-progression. Among the top molecular features associated with longer PFS were markers of estrogen signaling such as PGR gene expression (p=6.76e-04, HR=0.565) and the Hallmark estrogen response signature (p=0.021, HR=0.679). Applying a multi-omics pattern recognition algorithm, we identified a molecularly distinct cluster (IC1) characterized by down-regulation of estrogen signaling. IC1 is significantly associated with shorter PFS (p=3.72e-05, HR=0.22) and increased from 4% pre-treatment to 23% post-progression (p=7.3e-08). Further, IC1 is strongly enriched in markers previously implicated in CDK4/6i resistance including CCNE1 expression, RB1 mutation and MYC/E2F activation. We then developed machine learning models to predict gene-level dependency trained on cancer cell line expression and CRISPR-KO screen data. These models predicted decreased dependency on ESR1 and CDK4 and increased dependency on CDK2 in IC1, strengthening the association between ER independence and CDK4/6i resistance. Conclusions Our real-world clinical genomics study identified a comprehensive list of biomarkers associated with resistance to CDK4/6i plus ET and estimated patient prevalence for these markers in the post-treatment setting. Integrated and machine-learning analyses identified a subset of aggressive tumors with estrogen independence characteristics that are implicated in CDK4/6i resistance and suggested new therapeutic strategies. Citation Format: Zhengyan Kan, Ji Wen, Jennifer Webster, Vinicius Bonato, Whijae Roh, Xinmeng Jasmine Mu, Paul Rejto, Jadwiga Bienkowska. Real-world clinical genomics study of HR+/HER2- metastatic breast cancers treated by CDK4/6i plus endocrine therapies revealed a drug resistant tumor segment characterized by ER independence [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 PO1-14-08.

Abstract PO5-08-11: Genetic Landscape of Early Breast Cancer in an Ashkenazi Jewish Cohort

Abstract Background: The Ashkenazi Jewish (AJ) population exhibits a distinctive mutation profile in BRCA1 and BRCA2 (BRCA1/2), characterized by 3 common founder mutations: BRCA1 185delAG, BRCA1 5382insC, and BRCA2 6174delT. These 3 mutations are associated with 10% of invasive breast cancer (BC) cases among AJ women. However, the frequency of non-founder pathogenic variants in BRCA1/2 and other BC-related genes in AJ women with BC remains unclear. Methods: This retrospective study included AJ patients diagnosed with stage I-II human epidermal receptor growth factor 2 negative BC between 2004-2022 at the Weill Cornell Breast Center. We collected clinicopathological characteristics and genetic information to determine the frequency of predisposing mutations in BC and non-BC related genes in AJ patients with early BC. We also analyzed the clinicopathological characteristics and outcomes of patients with and without germline mutations in these genes. Results: The study included 232 self-identified AJ patients, with 98% being females. The median age at BC diagnosis was 62 years (IQR: 50-70). Stage I and II cancers accounted for 68% and 32% of cases, respectively. Hormone receptor positivity (HR+) was observed in 71% of patients, while 29% had triple-negative tumors. Genetic testing was performed on 88% (n=203) of the patients, while 5% of patients declined to undergo genetic testing. Among the tested patients, 12% (n=25/203) had pathogenic variants in BRCA1 or BRCA2, with 44% and 16% of these corresponding to the BRCA1 and BRCA2 founder mutations, respectively. Testing beyond BRCA1/2 genes was conducted on 154 patients, and only 6% (n=9/154) were found to have pathogenic variants in CHEK2, while no mutations were detected in other prevalent BC-related genes, including PALB2 and ATM. Fourteen-percent of patients had pathogenic mutations in other genes including APC, CFTR, FH, DIS3L2, FANCC, MUTYH, NF1 and VHL. The frequency of pathogenic BRCA1/2 variants was inversely proportional to the age at BC diagnosis: 50% (n=8/16), 21% (n=8/39), 15% (n=6/40), and 3% (n=3/108) of patients diagnosed at age &amp;lt; 40, 40-49, 50-59, and &amp;gt;60 years, respectively, had a pathogenic variant in either BRCA1 or BRCA2. The frequency of founder mutations varied according to age at diagnosis: 63%, 75%, 17%, and 100% for patients aged &amp;lt; 40, 40-49, 50-59, and &amp;gt;60 years, respectively. Patients with BRCA1/2 mutations exhibited higher-risk clinicopathological features compared to those without mutations, including a higher proportion of high histological grade (88%), and triple-negative tumors (76%). Mastectomy was the primary surgical treatment for 56% and 23% of patients with and without BRCA1/2 mutations, respectively. No difference in disease-free survival was found between patients with and without BRCA1/2 mutations with a median follow up of 3 years (IQR: 1-4). Conclusions: In our cohort, 17% of AJ patients with early BC carried a pathogenic variant in a BC-related gene, with BRCA1/2 being the most commonly affected genes. The proportion of pathogenic variants in BRCA1/2 showed an inverse correlation with the age at BC diagnosis, reaching up to 50% in patients diagnosed under the age of 40. These findings contrast with the lower prevalence of pathogenic variants in BRCA1/2 (38%) reported in the existing literature for this age group. Additionally, 8% of patients had pathogenic variants in other tested cancer genes carrying a genetic predisposition to colorectal cancer (CRC). These findings contribute to our understanding of the genetic landscape of early BC in the AJ population and emphasize the importance of comprehensive genetic testing, particularly among young patients. These results also suggest the need for earlier and more frequent CRC screening in a population of BC patients that may not be adhering to recommended guidelines. Furthermore, our study provides insight into how this genetic landscape may vary when analyzing late-stage BC in women of AJ heritage. Citation Format: Laura Munoz Arcos, Eleonora Nicolò, Maira Pires, Letizia Pontolillo, Leticia Varella, Tessa Cigler, Eleni Andreopolu, Anne Moore, Ashley Schreier, Carlos Munoz-Zuluaga, Lisa Newman, Georgia Syrnioti, Massimo Cristofanilli. Genetic Landscape of Early Breast Cancer in an Ashkenazi Jewish Cohort [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 PO5-08-11.

Abstract PO1-08-01: Identifying a founder BRCA1 variant in the Qatari population With unique genotype – phenotype correlations

Abstract PURPOSE: Hereditary breast and ovarian cancer syndrome (HBOC) is the most common cause of hereditary breast &amp; ovarian cancers in Qatar and worldwide which is caused by pathogenic variants in the BRCA1&amp; BRCA2 genes. The aim of this retrospective study is to describe a common recurrent founder pathogenic variant in the BRCA1 gene that was observed in the native Qatari population with unique genotype-phenotype correlations. METHODS: Medical records of Qatari patients (affected &amp; unaffected) with personal and/or family history of breast &amp; ovarian cancers who carry pathogenic/likely pathogenic mutations in the BRCA1 &amp; BRCA2 genes were reviewed between 2013- 2020. Epidemiological information and clinical data were reviewed including age, gender, ethnic background, personal history of cancer, tumour characteristics and family history. We used frequencies and proportions to describe the data and used Kaplan-Meier curves and log-rank analysis to compare survival rates. For the analysis, we used Stata Corp. 2015. Stata Statistical Software: Release 14, College Station, TX: Stata Corp LP. Result: Our result confirms the presence of a common recurrent pathogenic variant in BRCA1 gene [(c.4787 C&amp;gt;A) (p. Ser 1596*)] among Qatari patients who belong to 8 consanguineous large families followed by BRCA1[ c.4065_4068delTCAA]. BRCA1 c.4787 variant is highly associated with early onset breast cancer specifically Invasive ductal carcinoma (IDC) triple negative breast cancer (stage I, grade III), rather than ovarian cancer. In addition, the c.4787 C&amp;gt;A was found to be highly penetrant in families for young onset breast cancer. Conclusion: We showed that BRCA1 c.4787 C&amp;gt;A pathogenic variant is a highly recurrent variant among Qatari consanguineous families and contributes to the early onset breast cancer in Qatar. Early identification of this variant can aide to improve patient’s survival &amp; guide early personalized treatment and prevention. Citation Format: Salha Al-Bader, Hind Habish, Reem Al Sulaiman, Hajer Al-Mulla, Hafedh Ghazouani. Identifying a founder BRCA1 variant in the Qatari population With unique genotype – phenotype correlations [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 PO1-08-01.