Large-scale application of ClinGen-InSiGHT APC-specific ACMG/AMP variant classification criteria leads to substantial reduction in VUS.

Pathogenic constitutional APC variants underlie familial adenomatous polyposis, the most common hereditary gastrointestinal polyposis syndrome. To improve variant classification and resolve the interpretative challenges of variants of uncertain significance (VUSs), APC-specific variant classification criteria were developed by the ClinGen-InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel (VCEP) based on the criteria of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP). A streamlined algorithm using the APC-specific criteria was developed and applied to assess all APC variants in ClinVar and the International Society for Gastrointestinal Hereditary Tumours (InSiGHT) international reference APC Leiden Open Variation Database (LOVD) variant database, which included a total of 10,228 unique APC variants. Among the ClinVar and LOVD variants with an initial classification of (likely) benign or (likely) pathogenic, 94% and 96% remained in their original categories, respectively. In contrast, 41% ClinVar and 61% LOVD VUSs were reclassified into clinically meaningful classes, the vast majority as (likely) benign. The total number of VUSs was reduced by 37%. In 24 out of 37 (65%) promising APC variants that remained VUS despite evidence for pathogenicity, a data-mining-driven work-up allowed their reclassification as (likely) pathogenic. These results demonstrated that the application of APC-specific criteria substantially reduced the number of VUSs in ClinVar and LOVD. The study also demonstrated the feasibility of a systematic approach to variant classification in large datasets, which might serve as a generalizable model for other gene- or disease-specific variant interpretation initiatives. It also allowed for the prioritization of VUSs that will benefit from in-depth evidence collection. This subset of APC variants was approved by the VCEP and made publicly available through ClinVar and LOVD for widespread clinical use.

Implementation of a dyadic nomenclature for monogenic diseases.

A core task when establishing the strength of evidence for a gene's role in a monogenic disorder is determining the appropriate disease entity to curate. Establishing this concept determines which evidence can be applied and quantified toward the final gene-disease validity, variant pathogenicity, or actionability classification. Genes with implications in more than one phenotype can necessitate a process of lumping and splitting, disease reorganization, and updates to disease nomenclature. Reappraisal of the names that are used as labels for disease entities is therefore a necessary and perpetual process. The Clinical Genome Resource (ClinGen), in collaboration with representatives from Monarch Disease Ontology (Mondo) and Online Inheritance in Man (OMIM), formed the Disease Naming Advisory Committee (DNAC) to develop guidance for groups faced with the need to establish the "curated disease entity" for gene-phenotype validity and variant pathogenicity and to update disease names for clinical use when necessary. The objective of this group was to harmonize guidance for disease naming across these nosologic entities and among ClinGen curation groups in collaboration with other disease-related professional groups. Here, we present the initial guidance developed by the DNAC with representative examples provided by the ClinGen expert panels and working groups that warranted nomenclature updates. We also discuss the broader implications of these efforts and their benefits for harmonization of gene-disease validity curation. Overall, this work sheds light on current inconsistencies and/or discrepancies and is designed to engage the broader community on how ClinGen defines monogenic disorders using a consistent approach for disease naming.

Update on Recommendations for Cancer Screening and Surveillance in Children with Genomic Instability Disorders.

Genomic instability disorders are characterized by DNA or chromosomal instability resulting in various clinical manifestations including developmental anomalies, immunodeficiency, and increased risk to develop cancers beginning in childhood. Many of these genomic instability disorders also present with exquisite sensitivity to anticancer treatments such as ionizing radiation and chemotherapy, which may further increase the risk of second cancers. In July 2023, the American Association of Cancer Research held the second Childhood Cancer Predisposition Workshop where multidisciplinary international experts discussed, reviewed, and updated recommendations for children with cancer predisposition syndromes. This article will discuss childhood cancer risks and surveillance recommendations for the group of genomic instability disorders with predominantly recessive inheritance, including the DNA repair disorders ataxia telangiectasia, Nijmegen breakage syndrome, Fanconi anemia, Xeroderma Pigmentosum, Bloom syndrome, and Rothmund-Thomson syndrome, as well as the telomere biology disorders and mosaic variegated aneuploidy. Recognition of children with genomic instability disorders is important in order to make the proper diagnosis, enable genetic counseling, and inform cancer screening, cancer risk reduction, and choice of anti-cancer therapy.

Comparing the Diagnostic Yield of Germline Exome Versus Panel Sequencing in the Diverse Population of the Texas KidsCanSeq Pediatric Cancer Study.

PURPOSE: To evaluate the relative diagnostic yield of clinical germline genomic tests in a diverse pediatric cancer population. PATIENTS AND METHODS: The KidsCanSeq study enrolled pediatric cancer patients across six sites in Texas. Germline analysis included both exome sequencing and a therapy-focused pediatric cancer gene panel. The results were categorized by participants demographics, the presence of pathogenic or likely pathogenic (P/LP) variants, and variants of uncertain significance (VUS) in cancer predisposition genes (CPGs). Pediatric actionable CPGs were defined as those with cancer surveillance recommendations during childhood. RESULTS: Cancer P/LP variants were reported by at least one platform in 103 of 578 (17.8%) participants of which 76 were dominant cancer genes (13.1%) with no significant differences by self-described race or Hispanic ethnicity. However, the proportion of participants with VUS was greater in Asian and African American participants (P = .0029). Diagnostic yield was 16.6% for exome versus 8.5% for panel (P < .0001) with 42 participants with concordant germline results. Exome-only results included P/LP variants in 30 different CPGs in 54 participants, whereas panel-only results included seven participants with a copy number or structural P/LP variants in CPGs. There was no significant difference in diagnostic yield limited to pediatric actionable CPGs (P = .6171). CONCLUSION: Approximately 18% of a diverse pediatric cancer population had germline diagnostic findings with 50% of P/LP variants reported by only one platform because of CPGs not on the targeted panel and copy number variants (CNVs)/rearrangements not reported by exome. Although diagnostic yields were similar in this diverse population, increases in VUS results were observed in Asian and African American populations. Given the clinical significance of CNVs/rearrangements in this cohort, detection is critical to optimize germline analysis of pediatric cancer populations.

Pediatric Cancer Screening in Hereditary Gastrointestinal Cancer Risk Syndromes: An Update from the AACR Childhood Cancer Predisposition Working Group.

Gastrointestinal (GI) polyposis and cancer in pediatric patients is frequently due to an underlying hereditary cancer risk syndrome requiring ongoing cancer screening. Identification of at-risk patients through family history, clinical features of a syndrome, or symptom onset ensures appropriate cancer risk assessment and management in childhood and beyond. In this 2024 perspective, we outline updates to the hereditary GI cancer screening guidelines first published by the American Association of Cancer Research Pediatric Cancer Predisposition Workshop in 2017. These guidelines consider existing recommendations by pediatric and adult gastroenterology consortia to ensure alignment with gastroenterology practices in managing polyposis conditions. We specifically address the recommendations for pediatric screening in familial adenomatous polyposis, Peutz-Jeghers syndrome, and juvenile polyposis syndrome. Further, we emphasize the importance of multidisciplinary care and partnership with gastroenterology, as it is crucial in management of children and families with these conditions.

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.

Clinical Updates and Surveillance Recommendations for DNA Replication Repair Deficiency Syndromes in Children and Young Adults.

Replication repair deficiency (RRD) is a pan-cancer mechanism characterized by abnormalities in the DNA mismatch repair (MMR) system due to pathogenic variants in the PMS2, MSH6, MSH2, or MLH1 genes, and/or in the polymerase-proofreading genes POLE and POLD1. RRD predisposition syndromes (constitutional MMR deficiency, Lynch, and polymerase proofreading-associated polyposis) share overlapping phenotypic and biological characteristics. Moreover, cancers stemming from germline defects of one mechanism can acquire somatic defects in another, leading to complete RRD. Here we describe the recent advances in the diagnostics, surveillance, and clinical management for children with RRD syndromes. For patients with constitutional MMR deficiency, new data combining clinical insights and cancer genomics have revealed genotype-phenotype associations and helped in the development of novel functional assays, diagnostic guidelines, and surveillance recommendations. Recognition of non-gastrointestinal/genitourinary malignancies, particularly aggressive brain tumors, in select children with Lynch and polymerase proofreading-associated polyposis syndromes harboring an RRD biology have led to new management considerations. Additionally, universal hypermutation and microsatellite instability have allowed immunotherapy to be a paradigm shift in the treatment of RRD cancers independent of their germline etiology. These advances have also stimulated a need for expert recommendations about genetic counseling for these patients and their families. Future collaborative work will focus on newer technologies such as quantitative measurement of circulating tumor DNA and functional genomics to tailor surveillance and clinical care, improving immune surveillance; develop prevention strategies; and deliver these novel discoveries to resource-limited settings to maximize benefits for patients globally.

Systematic large-scale application of ClinGen InSiGHT APC -specific ACMG/AMP variant classification criteria substantially alleviates the burden of variants of uncertain significance in ClinVar and LOVD databases.

Background: Pathogenic constitutional APC variants underlie familial adenomatous polyposis, the most common hereditary gastrointestinal polyposis syndrome. To improve variant classification and resolve the interpretative challenges of variants of uncertain significance (VUS), APC-specific ACMG/AMP variant classification criteria were developed by the ClinGen-InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel (VCEP). Methods: A streamlined algorithm using the APC -specific criteria was developed and applied to assess all APC variants in ClinVar and the InSiGHT international reference APC LOVD variant database. Results: A total of 10,228 unique APC variants were analysed. Among the ClinVar and LOVD variants with an initial classification of (Likely) Benign or (Likely) Pathogenic, 94% and 96% remained in their original categories, respectively. In contrast, 41% ClinVar and 61% LOVD VUS were reclassified into clinically actionable classes, the vast majority as (Likely) Benign. The total number of VUS was reduced by 37%. In 21 out of 36 (58%) promising APC variants that remained VUS despite evidence for pathogenicity, a data mining-driven work-up allowed their reclassification as (Likely) Pathogenic. Conclusions: The application of APC -specific criteria substantially reduced the number of VUS in ClinVar and LOVD. The study also demonstrated the feasibility of a systematic approach to variant classification in large datasets, which might serve as a generalisable model for other gene-/disease-specific variant interpretation initiatives. It also allowed for the prioritization of VUS that will benefit from in-depth evidence collection. This subset of APC variants was approved by the VCEP and made publicly available through ClinVar and LOVD for widespread clinical use.

Genomic sequencing research in pediatric cancer care: Decision making, attitudes, and perceived utility among adolescents and young adults and their parents.

PURPOSE: Professional guidelines recommend engaging adolescents and young adults (AYAs) in medical decision making (DM), including whether to undergo genomic sequencing (GS). We explored DM around GS and attitudes after return of GS results among a diverse group of AYAs with cancer and their parents. METHODS: We surveyed AYAs with cancer (n = 75) and their parents (n = 52) 6 months after receiving GS results through the Texas KidsCanSeq study. We analyzed AYAs' DM role in GS research enrollment and their satisfaction with that role. We compared AYAs' and parents' self-reported understanding of, attitudes toward, and perceived utility of the AYA's GS results. RESULTS: Most AYAs reported equally sharing DM with their parents (55%) or leading DM (36%) about GS research. Compared with their cancer care DM role, 56% of AYAs reported the same level of involvement in GS research DM, whereas 32% were more involved, and 13% were less involved (P = .011). AYAs were satisfied (99%) with their DM role regarding GS study participation. AYAs and parents had similar self-reported understanding of, attitudes toward, and perceived utility of the GS results. CONCLUSION: Our results support engaging AYAs in DM about GS research and provide insights into AYAs' DM preferences and positive attitudes toward GS.

Generating Clinical-Grade Gene-Disease Validity Classifications Through the ClinGen Data Platforms.

Clinical genetic laboratories must have access to clinically validated biomedical data for precision medicine. A lack of accessibility, normalized structure, and consistency in evaluation complicates interpretation of disease causality, resulting in confusion in assessing the clinical validity of genes and genetic variants for diagnosis. A key goal of the Clinical Genome Resource (ClinGen) is to fill the knowledge gap concerning the strength of evidence supporting the role of a gene in a monogenic disease, which is achieved through a process known as Gene-Disease Validity curation. Here we review the work of ClinGen in developing a curation infrastructure that supports the standardization, harmonization, and dissemination of Gene-Disease Validity data through the creation of frameworks and the utilization of common data standards. This infrastructure is based on several applications, including the ClinGen GeneTracker, Gene Curation Interface, Data Exchange, GeneGraph, and website.

Defining and Reducing Variant Classification Disparities.

Background: Multiplexed Assays of Variant Effects (MAVEs) can test all possible single variants in a gene of interest. The resulting saturation-style data may help resolve variant classification disparities between populations, especially for variants of uncertain significance (VUS). Methods: We analyzed clinical significance classifications in 213,663 individuals of European-like genetic ancestry versus 206,975 individuals of non-European-like genetic ancestry from All of Us and the Genome Aggregation Database. Then, we incorporated clinically calibrated MAVE data into the Clinical Genome Resource's Variant Curation Expert Panel rules to automate VUS reclassification for BRCA1, TP53, and PTEN . Results: Using two orthogonal statistical approaches, we show a higher prevalence ( p ≤5.95e-06) of VUS in individuals of non-European-like genetic ancestry across all medical specialties assessed in all three databases. Further, in the non-European-like genetic ancestry group, higher rates of Benign or Likely Benign and variants with no clinical designation ( p ≤2.5e-05) were found across many medical specialties, whereas Pathogenic or Likely Pathogenic assignments were higher in individuals of European-like genetic ancestry ( p ≤2.5e-05). Using MAVE data, we reclassified VUS in individuals of non-European-like genetic ancestry at a significantly higher rate in comparison to reclassified VUS from European-like genetic ancestry ( p =9.1e-03) effectively compensating for the VUS disparity. Further, essential code analysis showed equitable impact of MAVE evidence codes but inequitable impact of allele frequency ( p =7.47e-06) and computational predictor ( p =6.92e-05) evidence codes for individuals of non-European-like genetic ancestry. Conclusions: Generation of saturation-style MAVE data should be a priority to reduce VUS disparities and produce equitable training data for future computational predictors.

Germline Genetic Testing and Survival Outcomes Among Children With Rhabdomyosarcoma: A Report From the Children's Oncology Group.

Importance: Determining the impact of germline cancer-predisposition variants (CPVs) on outcomes could inform novel approaches to testing and treating children with rhabdomyosarcoma. Objective: To assess whether CPVs are associated with outcome among children with rhabdomyosarcoma. Design, Setting, and Participants: In this cohort study, data were obtained for individuals, aged 0.01-23.23 years, newly diagnosed with rhabdomyosarcoma who were treated across 171 Children's Oncology Group sites from March 15, 1999, to December 8, 2017. Data analysis was performed from June 16, 2021, to May 15, 2023. Exposure: The presence of a CPV in 24 rhabdomyosarcoma-associated cancer-predisposition genes (CPGs) or an expanded set of 63 autosomal-dominant CPGs. Main Outcomes and Measures: Overall survival (OS) and event-free survival (EFS) were the main outcomes, using the Kaplan-Meier estimator to assess survival probabilities and the Cox proportional hazards regression model to adjust for clinical covariates. Analyses were stratified by tumor histology and the fusion status of PAX3 or PAX7 to the FOXO1 gene. Results: In this study of 580 individuals with rhabdomyosarcoma, the median patient age was 5.9 years (range, 0.01-23.23 years), and the male-to-female ratio was 1.5 to 1 (351 [60.5%] male). For patients with CPVs in rhabdomyosarcoma-associated CPGs, EFS was 48.4% compared with 57.8% for patients without a CPV (P = .10), and OS was 53.7% compared with 65.3% for patients without a CPV (P = .06). After adjustment, patients with CPVs had significantly worse OS (adjusted hazard ratio [AHR], 2.49 [95% CI, 1.39-4.45]; P = .002), and the outcomes were not better among patients with embryonal histology (EFS: AHR, 2.25 [95% CI, 1.25-4.06]; P = .007]; OS: AHR, 2.83 [95% CI, 1.47-5.43]; P = .002]). These associations were not due to the development of a second malignant neoplasm, and importantly, patients with fusion-negative rhabdomyosarcoma who harbored a CPV had similarly inferior outcomes as patients with fusion-positive rhabdomyosarcoma without CPVs (EFS: AHR, 1.35 [95% CI, 0.71-2.59]; P = .37; OS: AHR, 1.71 [95% CI, 0.84-3.47]; P = .14). There were no significant differences in outcome by CPV status of the 63 CPG set. Conclusions and Relevance: This cohort study identified a group of patients with embryonal rhabdomyosarcoma who had a particularly poor outcome. Other important clinical findings included that individuals with TP53 had poor outcomes independent of second malignant neoplasms and that patients with fusion-negative rhabdomyosarcoma who harbored a CPV had outcomes comparable to patients with fusion-positive rhabdomyosarcoma. These findings suggest that germline CPV testing may aid in clinical prognosis and should be considered in prospective risk-based clinical trials.

Adult-Onset Cancer Predisposition Syndromes in Children and Adolescents-To Test or not to Test?

With the increasing use of comprehensive germline genetic testing of children and adolescents with cancer, it has become evident that pathogenic variants (PV) in adult-onset cancer predisposition genes (aoCPG) underlying adult-onset cancer predisposition syndromes, such as Lynch syndrome or hereditary breast and ovarian cancer, are enriched and reported in 1% to 2% of children and adolescents with cancer. However, the causal relationship between PVs in aoCPGs and childhood cancer is still under investigation. The best-studied examples include heterozygous PVs in mismatch repair genes associated with Lynch syndrome in children with mismatch repair deficient high-grade glioma, heterozygous PVs in BARD1 in childhood neuroblastoma, and heterozygous PVs in BRCA2 in children with rhabdomyosarcoma. The low penetrance for pediatric cancers is considered to result from a combination of the low baseline risk of cancer in childhood and the report of only a modest relative risk of disease in childhood. Therefore, we do not advise that healthy children empirically be tested for PVs in an aoCPG before adulthood outside a research study. However, germline panel testing is increasingly being performed in children and adolescents with cancer, and exome and genome sequencing may be offered more commonly in this population in the future. The precise pediatric cancer risks and spectra associated with PVs in aoCPGs, underlying cellular mechanisms and somatic mutational signatures, as well as treatment response, second neoplasm risks, and psycho-oncological aspects require further research.

Families' experiences accessing care after genomic sequencing in the pediatric cancer context: "It's just been a big juggle".

Access to genomic sequencing (GS) and resulting recommendations have not been well described in pediatric oncology. GS results may provide a cancer predisposition syndrome (CPS) diagnosis that warrants screening and specialist visits beyond cancer treatment, including testing or surveillance for family members. The Texas KidsCanSeq (KCS) Study evaluated implementation of GS in a diverse pediatric oncology population. We conducted semi-structured interviews (n = 20) to explore experiences of KCS patients' families around learning about a CPS diagnosis and following up on recommended care. We used qualitative content analysis to develop themes and subthemes across families' descriptions of their experiences accessing care and to understand which factors presented barriers and/or facilitators. We found participants had difficulty differentiating which follow-up care recommendations were made for their child's current cancer treatment versus the CPS. In families' access to follow-up care for CPS, organizational factors were crucial: travel time and distance were common hardships, while coordination of care to streamline multiple appointments with different providers helped facilitate CPS care. Financial factors also impacted families' access to CPS-related follow-up care: having financial assistance and insurance were facilitators for families, while costs and lack of insurance posed as barriers for patients who lost coverage during transitions from pediatric to adult care, and for adult family members who had no coverage. Factors related to beliefs and perceptions, specifically perceiving the risk as less salient to them and feeling overwhelmed with the patient's cancer care, presented barriers to follow-up care primarily for family members. Regarding social factors, competing life priorities made it difficult for families to access follow-up care, though having community support alleviated these barriers. We suggest interventions to improve coordination of cancer treatment and CPS-related care and adherence to surveillance protocols for families as children age, such as care navigators and integrating longitudinal genetic counseling into hereditary cancer centers.

Pediatric cancer incidence among individuals with overgrowth syndromes and overgrowth features: A population-based assessment in seven million children.

BACKGROUND: Overgrowth syndromes (e.g., Beckwith-Wiedemann) are associated with an increased risk of pediatric cancer, although there are few population-based estimates of risk. There are also limited studies describing associations between other overgrowth features (e.g., hepatosplenomegaly) and pediatric cancer. Therefore, cancer risk among children with these conditions was evaluated with data from a large, diverse population-based registry linkage study. METHODS: This study includes all live births in Texas during the years 1999-2017. Children with overgrowth features and syndromes were identified from the Texas Birth Defects Registry; children with cancer were identified by linkage to the Texas Cancer Registry. Cox regression models were used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for the association between each overgrowth syndrome/feature and cancer, which were adjusted for infant sex and maternal age. RESULTS: In the total birth cohort (n = 6,997,422), 21,207 children were identified as having an overgrowth syndrome or feature. Children with Beckwith-Wiedemann syndrome were 42 times more likely to develop pediatric cancer (95% CI, 24.20-71.83), with hepatoblastoma being the most common, followed by Wilms tumor. The presence of any isolated overgrowth feature was associated with increased cancer risk (HR, 4.70; 95% CI, 3.83-5.77); associations were strongest for hepatosplenomegaly (HR, 23.04; 95% CI, 13.37-39.69) and macroglossia (HR, 11.18; 95% CI, 6.35-19.70). CONCLUSIONS: This population-based assessment confirmed prior findings that children with either overgrowth syndromes or features were significantly more likely to develop cancer. Overall, this study supports recommendations for cancer surveillance in children with these conditions and may also inform future research into cancer etiology.

Gene-specific ACMG/AMP classification criteria for germline APC variants: Recommendations from the ClinGen InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel.

PURPOSE: The Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel (VCEP) was established by the International Society for Gastrointestinal Hereditary Tumours and the Clinical Genome Resource, who set out to develop recommendations for the interpretation of germline APC variants underlying Familial Adenomatous Polyposis, the most frequent hereditary polyposis syndrome. METHODS: Through a rigorous process of database analysis, literature review, and expert elicitation, the APC VCEP derived gene-specific modifications to the ACMG/AMP (American College of Medical Genetics and Genomics and Association for Molecular Pathology) variant classification guidelines and validated such criteria through the pilot classification of 58 variants. RESULTS: The APC-specific criteria represented gene- and disease-informed specifications, including a quantitative approach to allele frequency thresholds, a stepwise decision tool for truncating variants, and semiquantitative evaluations of experimental and clinical data. Using the APC-specific criteria, 47% (27/58) of pilot variants were reclassified including 14 previous variants of uncertain significance (VUS). CONCLUSION: The APC-specific ACMG/AMP criteria preserved the classification of well-characterized variants on ClinVar while substantially reducing the number of VUS by 56% (14/25). Moving forward, the APC VCEP will continue to interpret prioritized lists of VUS, the results of which will represent the most authoritative variant classification for widespread clinical use.

Should secondary pharmacogenomic variants be actively screened and reported when diagnostic genome-wide sequencing is performed in a child?

This white paper was prepared by the Global Alliance for Genomics and Health Regulatory and Ethics Work Stream's Pediatric Task Team to review and provide perspective with respect to ethical, legal, and social issues regarding the return of secondary pharmacogenomic variants in children who have a serious disease or developmental disorder and are undergoing exome or genome sequencing to identify a genetic cause of their condition. We discuss actively searching for and reporting pharmacogenetic/genomic variants in pediatric patients, different methods of returning secondary pharmacogenomic findings to the patient/parents and/or treating clinicians, maintaining these data in the patient's health record over time, decision supports to assist using pharmacogenetic results in future treatment decisions, and sharing information in public databases to improve the clinical interpretation of pharmacogenetic variants identified in other children. We conclude by presenting a series of points to consider for clinicians and policymakers regarding whether, and under what circumstances, routine screening and return of pharmacogenomic variants unrelated to the indications for testing is appropriate in children who are undergoing genome-wide sequencing to assist in the diagnosis of a suspected genetic disease.

Combined Bioinformatic and Splicing Analysis of Likely Benign Intronic and Synonymous Variants Reveals Evidence for Pathogenicity.

Background: Current clinical variant analysis pipelines focus on coding variants and intronic variants within 10-20 bases of an exon-intron boundary that may affect splicing. The impact of newer splicing prediction algorithms combined with in vitro splicing assays on rare variants currently considered Benign/Likely Benign (B/LB) is unknown. Methods: Exome sequencing data from 576 pediatric cancer patients enrolled in the Texas KidsCanSeq study were filtered for intronic or synonymous variants absent from population databases, predicted to alter splicing via SpliceAI (>0.20), and scored as potentially deleterious by CADD (>10.0). Total cellular RNA was extracted from monocytes and RT-PCR products analyzed. Subsequently, rare synonymous or intronic B/LB variants in a subset of genes submitted to ClinVar were similarly evaluated. Variants predicted to lead to a frameshifted splicing product were functionally assessed using an in vitro splicing reporter assay in HEK-293T cells. Results: KidsCanSeq exome data analysis revealed a rare, heterozygous, intronic variant (NM_177438.3(DICER1):c.574-26A>G) predicted by SpliceAI to result in gain of a secondary splice acceptor site. The proband had a personal and family history of pleuropulmonary blastoma consistent with DICER1 syndrome but negative clinical sequencing reports. Proband RNA analysis revealed alternative DICER1 transcripts including the SpliceAI-predicted transcript.Similar bioinformatic analysis of synonymous or intronic B/LB variants (n=31,715) in ClinVar from 61 Mendelian disease genes yielded 18 variants, none of which could be scored by MaxEntScan. Eight of these variants were assessed (DICER1 n=4, CDH1 n=2, PALB2 n=2) using in vitro splice reporter assay and demonstrated abnormal splice products (mean 66%; range 6% to 100%). Available phenotypic information from submitting laboratories demonstrated DICER1 phenotypes in 2 families (1 variant) and breast cancer phenotypes for PALB2 in 3 families (2 variants). Conclusions: Our results demonstrate the power of newer predictive splicing algorithms to highlight rare variants previously considered B/LB in patients with features of hereditary conditions. Incorporation of SpliceAI annotation of existing variant data combined with either direct RNA analysis or in vitro assays has the potential to identify disease-associated variants in patients without a molecular diagnosis.

Circulating tumor DNA sequencing of pediatric solid and brain tumor patients: An institutional feasibility study.

The potential of circulating tumor DNA (ctDNA) analysis to serve as a real-time "liquid biopsy" for children with central nervous system (CNS) and non-CNS solid tumors remains to be fully elucidated. We conducted a study to investigate the feasibility and potential clinical utility of ctDNA sequencing in pediatric patients enrolled on an institutional clinical genomics trial. A total of 240 patients had tumor DNA profiling performed during the study period. Plasma samples were collected at study enrollment from 217 patients and then longitudinally from a subset of patients. Successful cell-free DNA extraction and quantification occurred in 216 of 217 (99.5%) of these initial samples. Twenty-four patients were identified whose tumors harbored 30 unique variants that were potentially detectable on a commercially-available ctDNA panel. Twenty of these 30 mutations (67%) were successfully detected by next-generation sequencing in the ctDNA from at least one plasma sample. The rate of ctDNA mutation detection was higher in patients with non-CNS solid tumors (7/9, 78%) compared to those with CNS tumors (9/15, 60%). A higher ctDNA mutation detection rate was also observed in patients with metastatic disease (9/10, 90%) compared to non-metastatic disease (7/14, 50%), although tumor-specific variants were detected in a few patients in the absence of radiographic evidence of disease. This study illustrates the feasibility of incorporating longitudinal ctDNA analysis into the management of relapsed or refractory patients with childhood CNS or non-CNS solid tumors.

Associations between birth defects and childhood and adolescent germ cell tumors according to sex, histologic subtype, and site.

BACKGROUND: Studies have reported increased rates of birth defects among children with germ cell tumors (GCTs). However, few studies have evaluated associations by sex, type of defect, or tumor characteristics. METHODS: Birth defect-GCT associations were evaluated among pediatric patients (N = 552) with GCTs enrolled in the Germ Cell Tumor Epidemiology Study and population-based controls (N = 6380) without cancer from the Genetic Overlap Between Anomalies and Cancer in Kids Study. The odds ratio (OR) and 95% confidence interval (CI) of GCTs according to birth defects status were estimated by using unconditional logistic regression. All defects were considered collectively and by genetic and chromosomal syndromes and nonsyndromic defects. Stratification was by sex, tumor histology (yolk sac tumor, teratoma, germinoma, and mixed/other), and location (gonadal, extragonadal, and intracranial). RESULTS: Birth defects and syndromic defects were more common among GCT cases than controls (6.9% vs. 4.0% and 2.7% vs. 0.2%, respectively; both p < .001). In multivariable models, GCT risk was increased among children with birth defects (OR, 1.7; 95% CI, 1.3-2.4) and syndromic defects (OR, 10.4; 95% CI, 4.9-22.1). When stratified by tumor characteristics, birth defects were associated with yolk sac tumors (OR, 2.7; 95% CI, 1.3-5.0) and mixed/other histologies (OR, 2.1; 95% CI, 1.2-3.5) and both gonadal tumors (OR, 1.7; 95% CI, 1.0-2.7) and extragonadal tumors (OR, 3.8; 95% CI, 2.1-6.5). Nonsyndromic defects specifically were not associated with GCTs. In sex-stratified analyses, associations were observed among males but not females. CONCLUSIONS: These data suggest that males with syndromic birth defects are at an increased risk of pediatric GCTs, whereas males with nonsyndromic defects and females are not at an increased risk. PLAIN LANGUAGE SUMMARY: We investigated whether birth defects (such as congenital heart disease or Down syndrome) are linked to childhood germ cell tumors (GCTs), cancers that mainly develop in the ovaries or testes. We studied different types of birth defects (defects that were caused by chromosome changes such as Down syndrome or Klinefelter syndrome and defects that were not) and different types of GCTs. Only chromosome changes such as Down syndrome or Klinefelter syndrome were linked to GCTs. Our study suggests that most children with birth defects are not at an increased risk of GCTs because most birth defects are not caused by chromosome changes.