Constitutional balanced translocations involving SMARCB1: A rare cause of rhabdoid tumor predisposition syndrome.

Rhabdoid Tumor Predisposition Syndrome 1 (RTPS1) confers an increased risk of developing rhabdoid tumors and is caused by germline mutations in SMARCB1. RTPS1 should be evaluated in all individuals with rhabdoid tumor and is more likely in those with a young age at presentation (occasionally congenital presentation), multiple primary tumors, or a family history of rhabdoid tumor or RTPS1. Proband genetic testing is the standard method for diagnosing RTPS1. Most known RTPS1-related SMARCB1 gene mutations are copy number variants (CNVs) or single nucleotide variants/indels, but structural variant analysis (SVA) is not usually included in the molecular evaluation. Here, we report two children with RTPS1 presenting with atypical teratoid/rhabdoid tumor (ATRT) who had constitutional testing showing balanced chromosome translocations involving SMARCB1. Patient 1 is a 23-year-old female diagnosed with pineal region ATRT at 7 months who was found to have a de novo, constitutional t(16;22)(p13.3;q11.2). Patient 2 is a 24-month-old male diagnosed with a posterior fossa ATRT at 14 months, with subsequent testing showing a constitutional t(5;22)(q14.1;q11.23). These structural rearrangements have not been previously reported in RTPS1. While rare, these cases suggest that structural variants should be considered in the evaluation of children with rhabdoid tumors to provide more accurate genetic counseling on the risks of developing tumors, the need for surveillance, and the risks of passing the disorder on to future children. Further research is needed to understand the prevalence, clinical features, and tumor risks associated with RTPS1-related constitutional balanced translocations.

NCKAP1 Disruptive Variants Lead to a Neurodevelopmental Disorder with Core Features of Autism.

NCKAP1/NAP1 regulates neuronal cytoskeletal dynamics and is essential for neuronal differentiation in the developing brain. Deleterious variants in NCKAP1 have been identified in individuals with autism spectrum disorder (ASD) and intellectual disability; however, its clinical significance remains unclear. To determine its significance, we assemble genotype and phenotype data for 21 affected individuals from 20 unrelated families with predicted deleterious variants in NCKAP1. This includes 16 individuals with de novo (n = 8), transmitted (n = 6), or inheritance unknown (n = 2) truncating variants, two individuals with structural variants, and three with potentially disruptive de novo missense variants. We report a de novo and ultra-rare deleterious variant burden of NCKAP1 in individuals with neurodevelopmental disorders which needs further replication. ASD or autistic features, language and motor delay, and variable expression of intellectual or learning disability are common clinical features. Among inherited cases, there is evidence of deleterious variants segregating with neuropsychiatric disorders. Based on available human brain transcriptomic data, we show that NCKAP1 is broadly and highly expressed in both prenatal and postnatal periods and demostrate enriched expression in excitatory neurons and radial glias but depleted expression in inhibitory neurons. Mouse in utero electroporation experiments reveal that Nckap1 loss of function promotes neuronal migration during early cortical development. Combined, these data support a role for disruptive NCKAP1 variants in neurodevelopmental delay/autism, possibly by interfering with neuronal migration early in cortical development.

Diagnostic criteria for constitutional mismatch repair deficiency (CMMRD): recommendations from the international consensus working group.

BACKGROUND: Constitutional mismatch repair deficiency syndrome (CMMRD) is the most aggressive cancer predisposition syndrome associated with multiorgan cancers, often presenting in childhood. There is variability in age and presentation of cancers and benign manifestations mimicking neurofibromatosis type 1. Genetic testing may not be informative and is complicated by pseudogenes associated with the most commonly associated gene, PMS2. To date, no diagnostic criteria exist. Since surveillance and immune-based therapies are available, establishing a CMMRD diagnosis is key to improve survival. METHODS: In order to establish a robust diagnostic path, a multidisciplinary international working group, with representation from the two largest consortia (International Replication Repair Deficiency (IRRD) consortium and European Consortium Care for CMMRD (C4CMMRD)), was formed to establish diagnostic criteria based on expertise, literature review and consensus. RESULTS: The working group established seven diagnostic criteria for the diagnosis of CMMRD, including four definitive criteria (strong evidence) and three likely diagnostic criteria (moderate evidence). All criteria warrant CMMRD surveillance. The criteria incorporate germline mismatch repair results, ancillary tests and clinical manifestation to determine a diagnosis. Hallmark cancers for CMMRD were defined by the working group after extensive literature review and consultation with the IRRD and C4CMMRD consortia. CONCLUSIONS: This position paper summarises the evidence and rationale to provide specific guidelines for CMMRD diagnosis, which necessitates appropriate surveillance and treatment.

Speaking genomics to parents offered germline testing for cancer predisposition: Use of a 2-visit consent model.

BACKGROUND: Patients with cancer are increasingly offered genomic sequencing, including germline testing for cancer predisposition or other disorders. Such testing is unfamiliar to patients and families, and clear communication is needed to introduce genomic concepts and convey risk and benefit information. METHODS: Parents of children with cancer were offered the opportunity to have their children's tumor and germline examined with clinical genomic sequencing. Families were introduced to the study with a 2-visit informed consent model. Baseline genetic knowledge and self-reported literacy/numeracy were collected before a study introduction visit, during which basic concepts related to genomic sequencing were discussed. Information was reinforced during a second visit, during which informed consent was obtained and a posttest was administered. RESULTS: As reflected by the percentage of correct answers on the pretest and posttest assessments, this model increased genetic knowledge by 11.1% (from 77.8% to 88.9%; P < .0001) in 121 parents participating in both the study introduction and consent visits. The percentage of parents correctly identifying the meaning of somatic and germline mutations increased significantly (from 18% to 59% [somatic] and from 31% to 64% [germline]; P < .0001). Nevertheless, these concepts remained unfamiliar to one-third of the parents. No relation was identified between the change in the overall percentage of correct answers and self-reported literacy, numeracy, or demographics. CONCLUSIONS: The use of a 2-visit communication model improved knowledge of concepts relevant to genomic sequencing, particularly differences between somatic and germline testing; however, these areas remained confusing to many participants, and reinforcement may be necessary to achieve complete understanding.

Germline Mutations in Predisposition Genes in Pediatric Cancer.

BACKGROUND: The prevalence and spectrum of predisposing mutations among children and adolescents with cancer are largely unknown. Knowledge of such mutations may improve the understanding of tumorigenesis, direct patient care, and enable genetic counseling of patients and families. METHODS: In 1120 patients younger than 20 years of age, we sequenced the whole genomes (in 595 patients), whole exomes (in 456), or both (in 69). We analyzed the DNA sequences of 565 genes, including 60 that have been associated with autosomal dominant cancer-predisposition syndromes, for the presence of germline mutations. The pathogenicity of the mutations was determined by a panel of medical experts with the use of cancer-specific and locus-specific genetic databases, the medical literature, computational predictions, and second hits identified in the tumor genome. The same approach was used to analyze data from 966 persons who did not have known cancer in the 1000 Genomes Project, and a similar approach was used to analyze data from an autism study (from 515 persons with autism and 208 persons without autism). RESULTS: Mutations that were deemed to be pathogenic or probably pathogenic were identified in 95 patients with cancer (8.5%), as compared with 1.1% of the persons in the 1000 Genomes Project and 0.6% of the participants in the autism study. The most commonly mutated genes in the affected patients were TP53 (in 50 patients), APC (in 6), BRCA2 (in 6), NF1 (in 4), PMS2 (in 4), RB1 (in 3), and RUNX1 (in 3). A total of 18 additional patients had protein-truncating mutations in tumor-suppressor genes. Of the 58 patients with a predisposing mutation and available information on family history, 23 (40%) had a family history of cancer. CONCLUSIONS: Germline mutations in cancer-predisposing genes were identified in 8.5% of the children and adolescents with cancer. Family history did not predict the presence of an underlying predisposition syndrome in most patients. (Funded by the American Lebanese Syrian Associated Charities and the National Cancer Institute.).

Malignant progression of a peripheral nerve sheath tumor in the setting of rhabdoid tumor predisposition syndrome.

Malignant progression of a benign or low-grade tumor in individuals with germline alteration of SMARCB1 gene is not well characterized. In a family in which two carrier children had germline SMARCB1 mutations and atypical teratoid rhabdoid tumor, we report malignant progression of a nerve sheath tumor over a 7-year period in an affected adult family member. Prompt identification of the germline SMARCB1 alteration and the resultant rhabdoid tumor predisposition syndrome can help guide genetic counseling and surveillance in affected family members.

Germline ETV6 Mutations Confer Susceptibility to Acute Lymphoblastic Leukemia and Thrombocytopenia.

Somatic mutations affecting ETV6 often occur in acute lymphoblastic leukemia (ALL), the most common childhood malignancy. The genetic factors that predispose to ALL remain poorly understood. Here we identify a novel germline ETV6 p. L349P mutation in a kindred affected by thrombocytopenia and ALL. A second ETV6 p. N385fs mutation was identified in an unrelated kindred characterized by thrombocytopenia, ALL and secondary myelodysplasia/acute myeloid leukemia. Leukemic cells from the proband in the second kindred showed deletion of wild type ETV6 with retention of the ETV6 p. N385fs. Enforced expression of the ETV6 mutants revealed normal transcript and protein levels, but impaired nuclear localization. Accordingly, these mutants exhibited significantly reduced ability to regulate the transcription of ETV6 target genes. Our findings highlight a novel role for ETV6 in leukemia predisposition.

Integrating next-generation sequencing into pediatric oncology practice: An assessment of physician confidence and understanding of clinical genomics.

BACKGROUND: The incorporation of genomic testing to identify targetable somatic alterations and predisposing germline mutations into the clinical setting is becoming increasingly more common. Despite its potential usefulness, to the authors' knowledge physician confidence with regard to understanding and applying genomic testing remains unclear, particularly within the realm of pediatric oncology. METHODS: Before initiating an institutional feasibility study regarding the integration of clinical genomic testing, the authors surveyed pediatric oncologists regarding their confidence around understanding of genomic testing, perceived usefulness of test results, preferences around the disclosure of germline test results, and possible risks and benefits of testing. RESULTS: Among survey respondents (52 of 88 contacted; response rate of 59%), only a minority were confident in interpreting, using, and discussing somatic (35%) or germline (27%) genomic test results. Providers who were confident in interpreting somatic results were significantly more likely to anticipate using the results to plan the treatment of patients with relapsed or refractory cancers (P = .009). Similarly, providers who reported confidence in interpreting germline results were significantly more likely to discuss and use these results as part of clinical care (P<.0001). The majority of physicians (93%), regardless of their level of confidence, wanted to speak to a genetic counselor before disclosing germline test results. CONCLUSIONS: Among physicians at a comprehensive pediatric cancer center, confidence in the interpretation, use, and discussion of oncology-based genomic test results appears to be low, both in terms of somatic and germline testing. To optimize the integration of genomic sequencing into cancer care, methods must be developed to improve basic competencies around cancer-based genomic testing. Given the complexities surrounding variant interpretation and genotype-phenotype relationships, interdisciplinary collaborations are warranted. Cancer 2017;123:2352-2359. © 2017 American Cancer Society.

Metachronous T-Lymphoblastic Lymphoma and Burkitt Lymphoma in a Child With Constitutional Mismatch Repair Deficiency Syndrome.

Constitutional mismatch repair deficiency (CMMRD) is a cancer predisposition syndrome associated with a high risk of developing early-onset malignancies of the blood, brain, and intestinal tract. We present the case of a patient with T-lymphoblastic lymphoma at the age of 3 years, followed by Burkitt lymphoma 10 years later. This patient also exhibited numerous nonmalignant findings including café au lait spots, lipomas, bilateral renal nodules, a nonossifying fibroma, multiple colonic adenomas, and a rapidly enlarging pilomatrixoma. The spectrum of malignant and nonmalignant neoplasms in this patient highlights the remarkable diversity, and early onset, of lesions seen in children with CMMRD.

Parathyroid Cancer in the Pediatric Patient.

CONTEXT: Parathyroid carcinoma is exceedingly rare in children. We describe a case of parathyroid cancer in a young female who was originally classified as benign and managed surgically. Upon her diagnosis with malignancy, concurrent with metastatic lung involvement, she was referred for medical and surgical palliation to control her symptomatic hypercalcemia. We briefly review published childhood cases, consider the challenges in differentiating malignant from benign hyperparathyroidism in this age group, and discuss the association of CDC73 mutations with parathyroid carcinoma. CASE PRESENTATION: A 13-year-old African American girl with a history of parathyroid adenoma, diagnosed at 8 years of age with multiple recurrences, presented with hypercalcemia and elevated parathyroid hormone when her disease had been reclassified as malignant. Germline gene analysis revealed a heterozygous partial deletion of CDC73. The patient underwent palliative surgery for disease metastatic to her lungs. She continues with medical management of her hypercalcemia. CONCLUSIONS: A case of pediatric parathyroid carcinoma associated with haploinsufficiency of CDC73 is discussed. We review all published cases of pediatric parathyroid carcinoma and offer diagnostic considerations for a parathyroid mass in a child.

Update on Genetic Counselor Practice and Recommendations for Pediatric Cancer Predisposition Evaluation and Surveillance.

In July 2023, the American Association for Cancer Research held the second Childhood Cancer Predisposition Workshop, at which international experts in pediatric cancer predisposition met to update the previously published 2017 consensus statements on pediatric cancer predisposition syndromes. Since 2017, advances in tumor and germline genetic testing and increased understanding of cancer predisposition in patients with pediatric cancer have led to significant changes in clinical care. Here, we provide an updated genetic counseling framework for pediatric oncology professionals. The framework includes referral indications and timing, somatic and germline genetic testing options, testing for adult-onset cancer predisposition syndromes in children with and without cancer, evolving genetic counseling models to meet the increased demand for genetic testing, barriers to cancer genetic testing and surveillance in children, and psychosocial and equity considerations regarding cancer genetic testing and surveillance in children. Adaptable genetic counseling services are needed to provide support to pediatric oncology provider teams and diverse patients with pediatric cancer, cancer predisposition, and their families.

Playing Russian Roulette: Parent and Adolescent Perspectives on Tumor Surveillance for Adolescents with Cancer Predisposition Syndromes.

PURPOSE: Cancer predisposition syndrome (CPS) surveillance allows for the early detection and treatment of neoplasms; however, the psychosocial impact of tumor surveillance is poorly understood for cancer-affected adolescents with CPS and their parents. To gain further insight, we qualitatively characterized the affective and cognitive experience of adolescents undergoing tumor surveillance. EXPERIMENTAL DESIGN: Adolescents with a history of cancer and their parents independently completed semistructured interviews querying their experience with the adolescent's tumor surveillance. Interviews were coded using emotion coding and content analysis before developing themes using thematic analysis. RESULTS: Eight adolescents and 11 parents (seven mothers, four fathers) completed interviews. Parent themes included maternal anxiety, relief following surveillance, fathers' positive expectations and emotions surrounding surveillance results, coping strategies, and perception of going through surveillance together with their child. Adolescent themes included normalization of surveillance, indifference about surveillance but excitement to return to the hospital, focus on physical and logistic aspects, relief focused on being done with scans, and belief that outcomes would be good. Past scans/surveillance experiences influencing surveillance feelings were a theme across both parents and adolescents. CONCLUSIONS: Our findings suggest that tumor surveillance is not causing marked emotional distress for cancer-affected adolescents with CPS. In contrast, mothers of cancer-affected adolescents undergoing surveillance may present with anxiety leading up to tumor surveillance and, for a subset, in between surveillance appointments. These observations highlight a need for ongoing psychosocial screening for families of children with CPS and a role for psychosocial providers in the multidisciplinary management of CPS.

Genomes for Nurses: Understanding and Overcoming Barriers to Nurses Utilizing Genomics.

Background: Genomic testing is an increasingly important technology within pediatric oncology that aids in cancer diagnosis, provides prognostic information, identifies therapeutic targets, and reveals underlying cancer predisposition. However, nurses lack basic knowledge of genomics and have limited self-assurance in using genomic information in their daily practice. This single-institution project was carried out at an academic pediatric cancer hospital in the United States with the aim to explore the barriers to achieving genomics literacy for pediatric oncology nurses. Method: This project assessed barriers to genomic education and preferences for receiving genomics education among pediatric oncology nurses, nurse practitioners, and physician assistants. An electronic survey with demographic questions and 15 genetics-focused questions was developed. The final survey instrument consisted of nine sections and was pilot-tested prior to administration. Data were analyzed using a ranking strategy, and five focus groups were conducted to capture more-nuanced information. The focus group sessions lasted 40 min to 1 hour and were recorded and transcribed. Results: Over 50% of respondents were uncomfortable with or felt unprepared to answer questions from patients and/or family members about genomics. This unease ranked as the top barrier to using genomic information in clinical practice. Discussion: These results reveal that most nurses require additional education to facilitate an understanding of genomics. This project lays the foundation to guide the development of a pediatric cancer genomics curriculum, which will enable the incorporation of genomics into nursing practice.

A content analysis of parents' reflections on pathogenic and uncertain pediatric oncology germline sequencing results.

Germline genomic sequencing is increasingly integrated into pediatric cancer care, with pathogenic cancer-predisposing variants identified among 5-18% of affected children and variants of uncertain significance (VUS) in up to 70%. Given the potential medical implications for children and their families, parents' psychosocial responses to learning results are important to understand. Parents of children with cancer who learned their children's germline pathogenic or VUS results following paired tumor and germline genomic sequencing described their cognitive and affective responses to results in an open-ended write-in question after disclosure (M = 10 months post-disclosure; range = 1-28). Responses were coded and categorized using content analysis, then compared across results using chi-square and Fisher's exact test. Parents of children with pathogenic (n = 9), VUS (n = 52), and pathogenic plus VUS results (n = 9) described negative emotions, positive reactions, mixed emotions (i.e., positive and negative emotions), and neutral reactions. Negative emotions were described significantly more frequently with pathogenic results than VUS only (χ2 = 5.19; p = .02), with peace of mind and empowerment only described for those with VUS. Parents also described approach(es) to coping (e.g., faith, plan of action) and reactions specific to the uncertainty of VUS (e.g., disappointment at no explanation for cancer etiology). A subset with VUS described decreasing worry/distress with increased understanding of results, whereas others displayed misconceptions regarding VUS. Screening for emotional adjustment is warranted for parents of children with cancer receiving pathogenic germline results, and screening for understanding is warranted with VUS. Findings highlight the importance of pre-and posttest genetic counseling.

Update on Cancer Predisposition Syndromes and Surveillance Guidelines for Childhood Brain Tumors.

Tumors of the central nervous system (CNS) comprise the second most common group of neoplasms in childhood. The incidence of germline predisposition among children with brain tumors continues to grow as our knowledge on disease etiology increases. Some children with brain tumors may present with nonmalignant phenotypic features of specific syndromes (e.g., nevoid basal cell carcinoma syndrome, neurofibromatosis type 1 and type 2, DICER1 syndrome, and constitutional mismatch-repair deficiency), while others may present with a strong family history of cancer (e.g., Li-Fraumeni syndrome) or with a rare tumor commonly found in the context of germline predisposition (e.g., rhabdoid tumor predisposition syndrome). Approximately 50% of patients with a brain tumor may be the first in a family identified to have a predisposition. The past decade has witnessed a rapid expansion in our molecular understanding of CNS tumors. A significant proportion of CNS tumors are now well characterized and known to harbor specific genetic changes that can be found in the germline. Additional novel predisposition syndromes are also being described. Identification of these germline syndromes in individual patients has not only enabled cascade testing of family members and early tumor surveillance but also increasingly affected cancer management in those patients. Therefore, the AACR Cancer Predisposition Working Group chose to highlight these advances in CNS tumor predisposition and summarize and/or generate surveillance recommendations for established and more recently emerging pediatric brain tumor predisposition syndromes.

Performance of Tumor Surveillance for Children With Cancer Predisposition.

Importance: Pediatric oncology patients are increasingly recognized as having an underlying cancer predisposition syndrome (CPS). Surveillance is often recommended to detect new tumors at their earliest and most curable stages. Data on the effectiveness and outcomes of surveillance for children with CPS are limited. Objective: To evaluate the performance of surveillance across a wide spectrum of CPSs. Design, Setting, and Participants: This cohort study reviewed surveillance outcomes for children and young adults from birth to age 23 years with a clinical and/or molecular CPS diagnosis from January 1, 2009, through September 31, 2021. Patients were monitored using standard surveillance regimens for their corresponding CPS at a specialty pediatric oncology center. Patients with hereditary retinoblastoma and bone marrow failure syndromes were excluded. Data were analyzed between August 1, 2021, and December 6, 2023. Exposure: Cancer predisposition syndrome. Main Outcomes and Measures: Outcomes of surveillance were reviewed to evaluate the incidence, spectrum, and clinical course of newly detected tumors. Surveillance modalities were classified for accuracy and assessed for common strengths and weaknesses. Results: A total of 274 children and young adults (mean age, 8 years [range, birth to 23 years]; 144 female [52.6%]) with 35 different CPSs were included, with a median follow-up of 3 years (range, 1 month to 12 years). During the study period, 35 asymptomatic tumors were detected in 27 patients through surveillance (9.9% of the cohort), while 5 symptomatic tumors were detected in 5 patients (1.8% of the cohort) outside of surveillance, 2 of whom also had tumors detected through surveillance. Ten of the 35 tumors (28.6%) were identified on first surveillance imaging. Malignant solid and brain tumors identified through surveillance were more often localized (20 of 24 [83.3%]) than similar tumors detected before CPS diagnosis (71 of 125 [56.8%]; P < .001). Of the 24 tumors identified through surveillance and surgically resected, 17 (70.8%) had completely negative margins. When analyzed across all imaging modalities, the sensitivity (96.4%), specificity (99.6%), positive predictive value (94.3%), and negative predictive value (99.6%) of surveillance were high, with few false-positive (6 [0.4%]) or false-negative (5 [0.3%]) findings. Conclusions and Relevance: These findings suggest that standardized surveillance enables early detection of new tumors across a wide spectrum of CPSs, allowing for complete surgical resection and successful treatment in the majority of patients.

Update on Recommendations for Surveillance for Children with Predisposition to Hematopoietic Malignancy.

Children harboring certain germline gene variants have an increased risk of developing myelodysplastic syndrome (MDS) and other hematopoietic malignancies (HM), such as leukemias and lymphomas. Recent studies have identified an expanding number of these predisposition genes, with variants most prevalent in children with MDS but also found in children with other HM. For some hematopoietic malignancy predispositions (HMP), specifically those with a high risk of MDS, early intervention through hematopoietic stem cell transplantation can favorably impact overall survival, providing a rationale for rigorous surveillance. A multidisciplinary panel of experts at the 2023 AACR Childhood Cancer Predisposition Workshop reviewed the latest advances in the field and updated prior 2017 surveillance recommendations for children with HMP. In addition to general guidance for all children with HMP, which includes annual physical examination, education about the signs and symptoms of HM, consultation with experienced providers, and early assessment by a hematopoietic stem cell transplantation specialist, the panel provided specific recommendations for individuals with a higher risk of MDS based on the affected gene. These recommendations include periodic and comprehensive surveillance for individuals with those syndromes associated with higher risk of MDS, including serial bone marrow examinations to monitor for morphologic changes and deep sequencing for somatic changes in genes associated with HM progression. This approach enables close monitoring of disease evolution based on the individual's genetic profile. As more HMP-related genes are discovered and the disorders' natural histories are better defined, these personalized recommendations will serve as a foundation for future guidelines in managing these conditions.

Pathogenic Variants in Adult-Onset Cancer Predisposition Genes in Pediatric Cancer: Prevalence and Impact on Tumor Molecular Features and Clinical Management.

PURPOSE: Clinical genomic sequencing of pediatric tumors is increasingly uncovering pathogenic variants in adult-onset cancer predisposition genes (aoCPG). Nevertheless, it remains poorly understood how often aoCPG variants are of germline origin and whether they influence tumor molecular profiles and/or clinical care. In this study, we examined the prevalence, spectrum, and impacts of aoCPG variants on tumor genomic features and patient management at our institution. EXPERIMENTAL DESIGN: This is a retrospective study of 1,018 children with cancer who underwent clinical genomic sequencing of their tumors. Tumor genomic data were queried for pathogenic variants affecting 24 preselected aoCPGs. Available tumor whole-genome sequencing (WGS) data were evaluated for second hit mutations, loss of heterozygosity (LOH), DNA mutational signatures, and homologous recombination deficiency (HRD). Patients whose tumors harbored one or more pathogenic aoCPG variants underwent subsequent germline testing based on hereditary cancer evaluation and family or provider preference. RESULTS: Thirty-three patients (3%) had tumors harboring pathogenic variants affecting one or more aoCPGs. Among 21 tumors with sufficient WGS sequencing data, six (29%) harbored a second hit or LOH affecting the remaining aoCPG allele with four of these six tumors (67%) also exhibiting a DNA mutational signature consistent with the altered aoCPG. Two additional tumors demonstrated HRD, of uncertain relation to the identified aoCPG variant. Twenty-one of 26 patients (81%) completing germline testing were positive for the aoCPG variant in the germline. All germline-positive patients were counseled regarding future cancer risks, surveillance, and risk-reducing measures. No patients had immediate cancer therapy changed due to aoCPG data. CONCLUSIONS: AoCPG variants are rare in pediatric tumors; however, many originate in the germline. Almost one third of tumor aoCPG variants examined exhibited a second hit and/or conferred an abnormal DNA mutational profile suggesting a role in tumor formation. aoCPG information aids in cancer risk prediction but is not commonly used to alter the treatment of pediatric cancers.

Parental Understanding of Their Child's Germline Genomic Testing: Intent of Disclosure to Their Child and Family.

Genomic testing is becoming increasingly common in the care of pediatric patients with cancer. Parental understanding of germline results and their intent and timing of results disclosure to their child and family may have significant implications on the family unit. The purpose of this study was to examine parental understanding of germline genomic results and plans for disclosure to their child and other relatives. Semi-structured interviews were conducted with 64 parents of children with cancer, approximately eight weeks after parents had received their child's results. Parents of children with negative results (n = 20), positive results (n = 15), or variants of uncertain significance (n = 29), were interviewed. Fifty-three parents (83%) correctly identified their child's results as negative, uncertain, or positive. Most parents had disclosed results to family members; however, only 11 parents (17%) acknowledged discussing results with their child. Most parents delayed disclosure due to the young age of their child at the time of testing. In summary, most parents appropriately described their child's germline genomic results, yet few discussed the results with their child due to age. Families should be followed with supportive counseling to assist parents in the timing and content of result disclosure to their children.