P502: CLINICAL IMPLEMENTATION OF GERMLINE GENETIC TESTING FOR HEMATOLOGIC DISORDERS

Clinical Impact of TERT A1062T Mutations in Younger Patients with Acute Myeloblastic Leukemia

Hypertrophic cardiomyopathy (HCM) is a common monogenetic cardiac disease with a prevalence of 0.2%1 that usually is inherited as an autosomal dominant trait with variable penetrance and expression. Clinically, HCM is defined by the presence of left ventricular (LV) hypertrophy (LVH) unexplained by abnormal loading conditions.1 The natural history varies from an asymptomatic course to drug-refractory angina/dyspnea, sudden cardiac death (SCD), and end-stage heart failure. The incidence of HCM-related SCD is approximately 1% to 2% in children and adolescents and 0.5% to 1% in adults.2,3 In this review, we examine the impact of advanced diagnostic imaging technologies on HCM, with particular emphasis on the detection of particular genetic subtypes. In ≈60% of cases, HCM is inherited as an autosomal dominant trait caused by mutations in genes coding for cardiac sarcomere proteins (Figure 1).4–7 Mutations in genes encoding Z-disc proteins and proteins involved in calcium regulation account for <5% of cases. The absence of sarcomeric gene mutations can be explained by limitations of current mutation detection techniques or mutations in as yet unidentified genes, but in some cases, hypertrophy is caused by other diseases that mimic the phenotype of sarcomeric protein disease. Table 1 lists genetic disorders associated with HCM. Figure 1. A schematic illustration of a cardiac sarcomere. View this table: Table 1. Currently Known Genes Implicated in HCM More than 600 different sarcomeric gene mutations are reported in patients with HCM.8–16 The majority are missense mutations, but nonsense, frameshift, and in-frame insertion/deletion mutations also occur. Most mutations are characterized by incomplete penetrance and variable clinical expression likely due to locus heterogeneity and the effect of mutations at different locations within the same gene. Most mutations probably have a dominant negative effect on sarcomere function, but in some cases, haploinsufficiency (ie, only a single functional …

Renal medullary carcinomas: histopathologic phenotype associated with diverse genotypes

Background: Prior work from our group has shown a high rate of familial breast cancer (BC) among rural BC patients (pts), with 33% reporting &amp;gt; 1 first-degree family members with BC and 55% meeting NCCN germline genetic testing (GGT) criteria (Shelton CH et al. NC Med. J; 2022). In 2018, we increased GGT to include all BC pts and observed: 1) many pts were out-of-criteria per NCCN guidelines but had actionable pathogenic germline variants (PGVs) and 2) knowledge of GGT factored significantly into shared decision making by providers and patients, including for positive and negative results. Beginning in 2019, concurrent with the recommendation from the American Society of Breast Surgeons, we expanded this model of universal GGT to an IRB-approved study to measure the impact of prospective testing on shared decision-making. Herein we report the real-world implementation of universal GGT for patients with BC and genetics-informed treatment decision-making in a rural community practice. Methods: From 2019-2022 all BC pts at a small, rural community hospital were offered GGT. Demographics, clinical features, and GGT results were collected along with clinician-reported clinical recommendations for treatment based on GGT results. Descriptive statistics and two-tailed Fisher’s exact test were employed and significance was set at p&amp;lt; 0.05. Results: 210 BC pts were offered GGT and 192 (91%) underwent testing [97% female, 95% non-Hispanic White, mean age at diagnosis of 62, 75% Stage I], with all but 7 pts completing GGT before primary treatment decisions. 104 (54%) of patients were in-criteria (IC) and 88 (46%) out-of-criteria (OOC) with NCCN GGT guidelines. PGVs were identified in 25 pts (13%) and 15 genes, most commonly BRCA1/2 (5 pts), PALB2 (3), monoallelic MUTYH (3) and ATM, BARD1, CHEK2 (2 pts each). PGV frequencies were 15% in IC and 11% in OOC patients (p=0.495). 46 (24%) pts had only a variant of uncertain significance (VUS) results. 70% of patients had &amp;gt; 1 clinical management change based on their GGT results. Changes in breast surgery, uptake of risk-reducing bilateral salpingo-oophorectomy, surveillance and clinical follow-up were significantly higher in patients with PGV compared to those with VUS/negative results (p &amp;lt; 0.0001). Compared to those with negative results, patients with PGVs in BRCA1 and BRCA2 were significantly more likely to undergo bilateral mastectomy (BLM) while those with PGVs in other genes or with VUS were not significantly more likely to elect for BLM than those with negative results. Clinicians reported that return of GGT reinforced their recommendation for 73/138 (53%) of patients who underwent breast-conserving therapy. GGT results aided in radiation therapy strategy for 54% of pts, most often resulting in dose de-escalation (accelerated fractionation) for negative/VUS pts (Table). Conclusions: Universal GGT for patients with BC was successfully implemented in a rural community practice with &amp;gt;90% uptake. Treatment was enhanced in those with clinically actionable PGVs and de-escalated in those without PGVs. Universal GGT for patients with BC is feasible to implement as the standard of practice within rural populations, enabling optimization of clinical care to patients’ genetic profile and may reduce unnecessary healthcare resource utilization. Universal Germline Genetic Testing for Breast Cancer: Implementation in a Rural Practice and Impact on Shared Decision Making Changes in Radiation Therapy Strategy based on GGT Citation Format: Charles Shelton, Sarah Nielsen, Antonio Ruiz, Lauren Shelton, Karen Freas, Sarah Poll, Brandie Heald, Daniel Pineda-Alvarez, Edward Esplin, Rachel Ellsworth, Hannah Montgomery. Universal Germline Genetic Testing for Breast Cancer: Implementation in a Rural Practice and Impact on Shared Decision Making [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 PO1-08-04.

Background: Breast cancer is the most common non-cutaneous malignancy among women, with around 10% of cases involving germline mutations in DNA repair genes. Germline mutations in BRCA1/2 genes significantly increase breast cancer risk. Other relevant genes to increase the risk of breast cancer include TP53, PTEN, PALB2, CHEK2, and ATM. Multigene panel testing can sequence many genes, sometimes identifying non-disease-related genes and variants of unknown significance. Methods: We reviewed patients with newly diagnosed breast cancer diagnosis from 2022 to 2024 in our institution. Germline genetic testing was offered to all newly diagnosed breast cancer patients at the time of diagnosis irrespective of their family history. Testing was offered to patients with invasive breast cancer and ductal carcinoma in situ. The goal of this study was to identify the prevalence of genes not attributed to increasing the risk of breast cancer and the implications of those results. Results: A total of 478 patients (Invasive cancer and DCIS) were seen in our oncology clinic from January 2022 to December 2024. The median age at diagnosis was 66 years (range 28-91). Invasive ductal cancer (IDC) was the most common subtype (66%), followed by DCIS (18%). Most patients had estrogen-positive cancer (81%), and approximately 14% had HER2-positive disease (62% HER2 low). We found 27 patients with pathogenic germline mutations which are not related to breast cancer risk. The most common mutation was MUYTH (7 patients), followed by FH gene (3 patients). MSH3, LZTR1, and HOXB13 genes were each found in 2 patients. APC, BAP1, BLM, BRIP1, NTHL1, SDHA, SDHB, MSH6, MITF, and FLCN genes were each identified in one patient. All patients with MUYTH mutations had hormone-positive (HER 2 negative) disease contrary to the limited observation of triple-negative breast cancer related to the MUYTH gene in the available literature. Patients with positive mutations were offered genetic counseling and referred to a high-risk genetics' clinic. FANCM was observed in one patient which has rarely been associated with an increased risk of triple-negative breast cancer. Conclusion: We present our single institution's experience of germline mutations in breast cancer patients. Previously, we observed CHEK2 being the most common breast cancer-related germline mutation in our patient population. This analysis focuses on identifying germline mutations without an increased risk of breast cancer. MUTYH was the most common pathogenic mutation identified. Further studies are needed to determine the actual risk percentage of breast cancer associated with the MUTYH gene. Universal testing for all breast cancer patients is feasible with the lower cost of multi-gene panels. However, identifying other non-disease-related genes, as observed in our study, has implications. Patients must be informed about the consequences of a positive result, including genetic counseling, additional screening tests, and testing of immediate family members. Citation Format: M. Zafar, M. Krishnakumar, A. Reddy. Non-breast cancer related germline mutations in breast cancer patients: a single institution experience [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS3-05-18.

ABSTRACTIntroduction: Telomere biology disorders (TBDs) encompass a group of illnesses caused by germline mutations in genes regulating telomere maintenance, resulting in very short telomeres. Possible TBD manifestations range from complex multisystem disorders with onset in childhood such as dyskeratosis congenita (DC), Hoyeraal-Hreidarsson syndrome, Revesz syndrome and Coats plus to adults presenting with one or two DC-related features.Areas covered: The discovery of multiple genetic causes and inheritance patterns has led to the recognition of a spectrum of clinical features affecting multiple organ systems. Patients with DC and associated TBDs are at high risk of bone marrow failure, cancer, liver and pulmonary disease. Recently, vascular diseases, including pulmonary arteriovenous malformations and gastrointestinal telangiectasias, have been recognized as additional manifestations. Diagnostics include detection of very short leukocyte telomeres and germline genetic testing. Hematopoietic cell transplantation and lung transplantation are the only current therapeutic modalities but are complicated by numerous comorbidities. This review summarizes the pathophysiology underlying TBDs, associated clinical features, management recommendations and therapeutic options.Expert opinion: Understanding TBDs as complex, multisystem disorders with a heterogenous genetic background and diverse phenotypes, highlights the importance of clinical surveillance and the urgent need to develop new therapeutic strategies to improve health outcomes.

Deleterious Germline Mutations in Telomere Maintenance Genes Identified in a Subset of Patients with Myelodysplastic Syndrome and Idiopathic Pulmonary Fibrosis

Germline Variants Associated with Cancer Predisposition and Bone Marrow Failure Are Common in KMT2A-r Infant Acute Lymphoblastic Leukemia Patients

Neurofibromin 1 gene Mutations Are Recurrent Events in Adult Patients with Acute Myeloid Leukemia (AML), Associate with Poor Outcome and Refine the Adverse European Leukemianet (ELN) Risk Category

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired GPI deficiency caused by somatic mutation of the PIGA gene in one or several hematopoietic stem cells. Recently, PNH caused by somatic mutation of one allele of the PIGT gene in combination with a germline mutation of the other allele was reported, showing that PIGA is not the only gene responsible for PNH, though other causes are rare. These mutant cells become GPI deficient, expand clonally and differentiate into all of the hematopoietic lineages. When GPI deficient erythrocytes increase in proportion, massive hemolysis occurs due to activated complement attack during infection. As the complement regulatory proteins such as CD59 and DAF are GPI anchored proteins, they are defective on GPI deficient erythrocytes and these abnormal erythrocytes are thereby left unprotected from complement attack. Hemolytic anemia, venous thrombosis, and bone marrow failure are thus the resulting triad of symptoms. Clonal expansion does not occur with PIGA deficiency alone. We hypothesize that PIGA deficient cells acquire a proliferative phenotype via additional gene mutations within the associated environment of bone marrow failure. This hypothesis will be explained by introducing recent reports.

Germ-Line and Somatic Mutations in Familial Myeloproliferative Neoplasms (MPNs). a Pilot Study

Characterization of Mutant MUTYH Proteins Associated With Familial Colorectal Cancer

Objective.To estimate the frequency of germline mutations in homologous recombination genes in a population of patients with pancreatic cancer and to assess the possibility to predict the risk of mutation carriage based on the clinical and anamnestic data.Materials and methods.The study included patients diagnosed with pancreatic cancer, blood samples of which were taken to detect clinically significant germline mutations in the BRCA1, BRCA2, CHEK2, BLM, NBS1, and PALB2 genes. Clinical data and family history data were collected for each patient.Results.The study included 99 patients. Mutations in BRCA1 gene were detected in 4 % of cases, in CHEK2 gene – in 2 %. No mutations were detected in the BRCA2, as in BLM, NBS1, and PALB2 genes. Localization of primary tumor, presence of distant metastases, stage of disease, family history of malignant neoplasms did not correlate with the risk of BRCA1 mutation (p&gt;0.05). The patient’s eligibility for NCCN criteria for BRCA1 gene mutation diagnosis proved to be a significant marker of germline mutation presence (p=0.043).Conclusions.NCCN criteria for genetic testing are the best predictor of BRCA1 germline mutation in patients with pancreatic cancer.

Abstract Background: Mutations in hereditary breast cancer genes play an essential role in cancer risk. Little is known of the type and frequency of mutations in Hispanic populations in the United States and Central American countries, including Guatemala. Methods: We used exome sequencing to identify mutations in blood DNA from unselected Hispanic breast cancer cases from community recruitment and from two hospitals each in Texas and Guatemala. Data from a structured questionnaire was used to compare mutation carriers of medium and high penetrance genes. Variants were annotated with ClinVar and VarSome. Results: We recruited 262 Hispanic US women, 37 (14%) from community-based recruitment and 225 (86%) from hospitals in Texas. In addition, we ascertained 633 patients from two hospitals in Guatemala City. A total of 91 out of 895 subjects (10%) had a variant classified as pathogenic in a gene with known high or medium penetrance for inherited breast cancer. The most frequently mutated genes were the high penetrance BRCA1 (44/895, 4.9%) followed by BRCA2 (23/895, 2.6%), PALB2 (5/895, 0.6%), CHEK2 (5/895 0.6%), ATM (6/895, 0.7%) and TP53 (6/895, 0.7%). Pathogenic variants were also detected in the moderate penetrance genes BARD1 and MSH6, and rare pathogenic variants detected in the low penetrance genes AXIN2, FH, MLH1, MSH2, MUTYH, NF1, and SDHB. The high ratio of BRCA1/BRCA2 mutations is due to the presence of two potential founder mutations, BRCA1 c.212+1G&amp;gt;A splice mutation (18 cases) and BRCA1 c.799delT (9 cases) in Guatemala. Compared to all others, cases with pathogenic mutations had a significantly earlier age at diagnosis (45 vs. 52 years, P&amp;lt;0.001) and were more likely to have a diagnosis before menopause. A higher percentage of mutation carriers had a relative with any cancer (51% vs. 37%, P=0.038) or breast cancer (33% vs. 15%, P&amp;lt;0.001). Patients with pathogenic mutations had a significantly higher percentage of triple-negative disease (60% vs. 13%, P=0.00046). Finally, mammography usage was less frequent in women with a lower socioeconomic status, indicating that this group is less likely to be screened for breast cancer (P&amp;lt;0.001). Conclusions: Guatemalan women have rates of hereditary breast cancer mutations like other populations, and these women are more likely to have early age at diagnosis, triple-negative disease, and family history. Patient recruitment was higher using hospital-based versus community enrollment. This data supports genetic testing in breast cancer patients and those at high risk as part of a strategy to reduce breast cancer mortality in Hispanic women. Citation Format: Jesica Godinez Paredes, Isabel Rodriguez, Megan Ren, Anali Orozco, Jeremy Ortiz, Anaseidy Albanez, Catherine Jones, Zeina Nahleh, Lilian Barreda, Lisa Garland, Dongjing Wu, Jiahui Wang, Victor Argueta, Roberto Orozco, Eduardo Gharzouzi, Michael Dean. Germline mutations in breast cancer genes are associated with early age of diagnosis and triple negative disease in Guatemalan and US Hispanic women [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 1938.

Germline Contributions to Clonal Hematopoiesis in Solid Cancer Patients