Actionability and familial uptake following opportunistic genomic screening in a pediatric cancer cohort.

The care for patients with serious conditions is increasingly guided by genomic medicine, and genomic medicine may equally transform care for healthy individual if genomic population screening is implemented. This study examines the medical impact of opportunistic genomic screening (OGS) in a cohort of patients undergoing comprehensive genomic germline DNA testing for childhood cancer, including the impact on their relatives. Medical actionability and uptake after cascade testing in the period following disclosure of OGS results was quantified. A secondary finding was reported to 19/595 (3.2%) probands primarily in genes related to cardiovascular and lipid disorders. After a mean follow up time of 1.6 years (Interquartile range (IQR): 0.57-1.92 yrs.) only 12 (63%) of these variants were found to be medically actionable. Clinical follow up or treatment was planned in 16 relatives, and as in the probands, the prescribed treatment was primarily betablockers or cholesterol lowering therapy. No invasive procedures or implantation of medical devices were performed in probands or relatives, and no reproductive counseling was requested. After an average of 1.6 years of follow-up 2.25 relatives per family with an actionable finding had been tested. This real-world experience of OGS grants new insight into the practical implementation effects and derived health care demands of genotype-first screening. The resulting health care effect and impact on demand for genetic counseling and workup in relatives extends beyond the effect in the probands.

The effect of a single SMARCA4 exon deletion on RNA splicing: Implications for variant classification.

BACKGROUND: Exon deletions are generally considered pathogenic, particularly when they are located out of frame. Here, we describe a pediatric, female patient presenting with hypercalcemia and a small cell carcinoma of the ovary, hypercalcemic type, and carrying a germline de novo SMARCA4 exon 14 deletion. METHODS: The SMARCA4 deletion was identified by whole genome sequencing, and the effect on the RNA level was examined by gel- and capillary electrophoresis and nanopore sequencing. RESULTS: The deletion was in silico predicted to be truncating, but RNA analysis revealed two major transcripts with deletion of exon 14 alone or exon 14 through 15, where the latter was located in-frame. Because the patient's phenotype matched that of other patients with pathogenic germline variants in SMARCA4, the deletion was classified as likely pathogenic. CONCLUSION: We propose to include RNA analysis in classification of single-exon deletions, especially if located outside of known functional domains, as this can identify any disparate effects on the RNA and DNA level, which may have implications for variant classification using the American College of Medical Genetics and Genomics guidelines.

Size matters in telomere biology disorders ‒ expanding phenotypic spectrum in patients with long or short telomeres.

The end of each chromosome consists of a DNA region termed the telomeres. The telomeres serve as a protective shield against degradation of the coding DNA sequence, as the DNA strand inevitably ‒ with each cell division ‒ is shortened. Inherited genetic variants cause telomere biology disorders when located in genes (e.g. DKC1, RTEL1, TERC, TERT) playing a role in the function and maintenance of the telomeres. Subsequently patients with telomere biology disorders associated with both too short or too long telomeres have been recognized. Patients with telomere biology disorders associated with short telomeres are at increased risk of dyskeratosis congenita (nail dystrophy, oral leukoplakia, and hyper- or hypo-pigmentation of the skin), pulmonary fibrosis, hematologic disease (ranging from cytopenia to leukemia) and in rare cases very severe multiorgan manifestations and early death. Patients with telomere biology disorders associated with too long telomeres have in recent years been found to confer an increased risk of melanoma and chronic lymphocytic leukemia. Despite this, many patients have an apparently isolated manifestation rendering telomere biology disorders most likely underdiagnosed. The complexity of telomere biology disorders and many causative genes makes it difficult to design a surveillance program which will ensure identification of early onset disease manifestation without overtreatment.

Germline (epi)genetics reveals high predisposition in females: a 5-year, nationwide, prospective Wilms tumour cohort.

BACKGROUND: Studies suggest that Wilms tumours (WT) are caused by underlying genetic (5%-10%) and epigenetic (2%-29%) mechanisms, yet studies covering both aspects are sparse. METHODS: We performed prospective whole-genome sequencing of germline DNA in Danish children diagnosed with WT from 2016 to 2021, and linked genotypes to deep phenotypes. RESULTS: Of 24 patients (58% female), 3 (13%, all female) harboured pathogenic germline variants in WT risk genes (FBXW7, WT1 and REST). Only one patient had a family history of WT (3 cases), segregating with the REST variant. Epigenetic testing revealed one (4%) additional patient (female) with uniparental disomy of chromosome 11 and Beckwith-Wiedemann syndrome (BWS). We observed a tendency of higher methylation of the BWS-related imprinting centre 1 in patients with WT than in healthy controls. Three patients (13%, all female) with bilateral tumours and/or features of BWS had higher birth weights (4780 g vs 3575 g; p=0.002). We observed more patients with macrosomia (>4250 g, n=5, all female) than expected (OR 9.98 (95% CI 2.56 to 34.66)). Genes involved in early kidney development were enriched in our constrained gene analysis, including both known (WT1, FBXW7) and candidate (CTNND1, FRMD4A) WT predisposition genes. WT predisposing variants, BWS and/or macrosomia (n=8, all female) were more common in female patients than male patients (p=0.01). CONCLUSION: We find that most females (57%) and 33% of all patients with WT had either a genetic or another indicator of WT predisposition. This emphasises the need for scrutiny when diagnosing patients with WT, as early detection of underlying predisposition may impact treatment, follow-up and genetic counselling.

Perception and management of cancer predisposition in pediatric cancer centers: A European-wide questionnaire-based survey.

The European Union-funded COST Action (LEukaemia GENe Discovery by data sharing, mining, and collaboration) LEGEND was an international and multidisciplinary collaboration between clinicians and researchers that covered a range of aspects of genetic predisposition in childhood leukemia. Within this framework, we explored the perception and handling of genetic predisposition in the daily practice of European treatment centers. Herein, we present the results of our questionnaire-based survey. We found that the overall awareness is quite high, and respondents remarked that identification and treatment of the most common predisposition syndromes were present. Nevertheless, high demand for continuous education and routinely updated resources remains.

Combinatorial batching of DNA for ultralow-cost detection of pathogenic variants.

BACKGROUND: Next-generation sequencing (NGS) based population screening holds great promise for disease prevention and earlier diagnosis, but the costs associated with screening millions of humans remain prohibitive. New methods for population genetic testing that lower the costs of NGS without compromising diagnostic power are needed. METHODS: We developed double batched sequencing where DNA samples are batch-sequenced twice - directly pinpointing individuals with rare variants. We sequenced batches of at-birth blood spot DNA using a commercial 113-gene panel in an explorative (n = 100) and a validation (n = 100) cohort of children who went on to develop pediatric cancers. All results were benchmarked against individual whole genome sequencing data. RESULTS: We demonstrated fully replicable detection of cancer-causing germline variants, with positive and negative predictive values of 100% (95% CI, 0.91-1.00 and 95% CI, 0.98-1.00, respectively). Pathogenic and clinically actionable variants were detected in RB1, TP53, BRCA2, APC, and 19 other genes. Analyses of larger batches indicated that our approach is highly scalable, yielding more than 95% cost reduction or less than 3 cents per gene screened for rare disease-causing mutations. We also show that double batched sequencing could cost-effectively prevent childhood cancer deaths through broad genomic testing. CONCLUSIONS: Our ultracheap genetic diagnostic method, which uses existing sequencing hardware and standard newborn blood spots, should readily open up opportunities for population-wide risk stratification using genetic screening across many fields of clinical genetics and genomics.

Hereditary polyposis syndromes remain a challenging disease entity: Old dilemmas and new insights.

In this editorial we present an overview and insights of the management of hereditary polyposis syndromes. The primary focus was on familial adenomatous polyposis, juvenile polyposis syndrome and Peutz-Jegher syndrome. Genetic testing has become increasingly available and is easier than ever to integrate into clinical practice. Furthermore, several genes have been added to the expanding list of genes associated with hereditary polyposis syndromes, allowing for precise diagnostics and tailored follow-up. Endoscopic evaluation of patients with hereditary polyposis syndromes is paramount in the surveillance strategies. Current endoscopic procedures include both diagnostic procedures and surveillance as well as therapeutic interventions. Recommendations for endoscopic procedures in the upper and lower gastrointestinal canal were described. Surgery is still a key component in the management of patients with hereditary polyposis syndromes. The increased cancer risk in these patients often render prophylactic procedures or intended curative procedures in the case of cancer development. Surgical interventions in the upper and lower gastrointestinal canal were described with relevant considerations. Development of chemopreventive medications is ongoing. Few drugs have been investigated, including nonsteroidal anti-inflammatory drugs. It has been demonstrated that cyclooxygenase-2 inhibitors may lower the number of polyps. Other medications are currently under investigation, but none have, to date, consistently been able to prevent development of disease.

Genetic predisposition and evolutionary traces of pediatric cancer risk: a prospective 5-year population-based genome sequencing study of children with CNS tumors.

BACKGROUND: The etiology of central nervous system (CNS) tumors in children is largely unknown and population-based studies of genetic predisposition are lacking. METHODS: In this prospective, population-based study, we performed germline whole-genome sequencing in 128 children with CNS tumors, supplemented by a systematic pedigree analysis covering 3543 close relatives. RESULTS: Thirteen children (10%) harbored pathogenic variants in known cancer genes. These children were more likely to have medulloblastoma (OR 5.9, CI 1.6-21.2) and develop metasynchronous CNS tumors (P = 0.01). Similar carrier frequencies were seen among children with low-grade glioma (12.8%) and high-grade tumors (12.2%). Next, considering the high mortality of childhood CNS tumors throughout most of human evolution, we explored known pediatric-onset cancer genes, showing that they are more evolutionarily constrained than genes associated with risk of adult-onset malignancies (P = 5e-4) and all other genes (P = 5e-17). Based on this observation, we expanded our analysis to 2986 genes exhibiting high evolutionary constraint in 141,456 humans. This analysis identified eight directly causative loss-of-functions variants, and showed a dose-response association between degree of constraint and likelihood of pathogenicity-raising the question of the role of other highly constrained gene alterations detected. CONCLUSIONS: Approximately 10% of pediatric CNS tumors can be attributed to rare variants in known cancer genes. Genes associated with high risk of childhood cancer show evolutionary evidence of constraint.

Preimplantation genetic testing in two Danish couples affected by Peutz-Jeghers syndrome.

BACKGROUND: Guidelines from the European Hereditary Tumor Group as well as The Danish National Guidelines for Peutz-Jeghers Syndrome (PJS) state that both prenatal diagnosis and preimplantation genetic testing for monogenic disorders (PGT-M) should be offered to patients with PJS. However, only a few cases resulting in viable pregnancies have been published. OBJECTIVE: We present two cases of PJS patients going through PGT-M for PJS. We highlight the awareness of this possibility and discuss the technical and ethical challenges of performing PGT-M for PJS. METHODS AND RESULTS: Case 1: A 36-year-old male with PJS and his partner were referred for genetic counseling. The patient carried a pathogenic de novo variant in STK11. After a terminated pregnancy of a fetus carrying the same pathogenic variant, microsatellite polymorphic marker analysis was established, and the patient was offered PGT-M. The female partner of the patient gave birth to a healthy boy after five years of fertility treatment. Case 2: A 35-year-old female with PJS and her partner were referred for genetic counseling. She carried an inherited pathogenic STK11 variant. The couple was offered PGT-M. Genetic testing of the embryos was performed using microsatellite polymorphic markers. After two rounds of oocyte extraction a blastocyst predicted not to be affected by PJS was identified. The blastocyst was transferred; however, this did not result in a viable pregnancy. CONCLUSIONS: PGT-M can be offered to patients with PJS. The process may be long and filled with ethical dilemmas requiring patients to be motivated and persistent.

[Telomere biology disorders].

The end of the chromosomes consists of DNA referred to as telomeres. The telomeres protect chromosomal DNA against shortening when cells divide. Patients with telomere biology disorders carry pathogenic germline variants in a gene involved in telomere function. New technologic advances have enabled us to identify more patients with telomere biology disorders, which in turn have increased our understanding of the phenotypic spectrum. The latter have proved wider than previously thought, and now we know that e.g. patients with isolated lung fibrosis can have an underlying telomere biology disorder.

Novel Genetic Causes of Gastrointestinal Polyposis Syndromes.

Hereditary polyposis syndromes are characterized by a large number and/or histopathologically specific polyps in the gastrointestinal tract and a high risk of both colorectal cancer and extracolonic cancer at an early age. While the genes responsible for some of the syndromes, eg, APC in familial adenomatous polyposis and STK11 in Peutz-Jeghers syndrome, have been known for decades, novel genetic causes have recently been detected that have shed light on the broader clinical spectrum of syndromes. Genetic diagnoses are important because they can facilitate a personalized surveillance program. Furthermore, at-risk members of the patient's family can be tested and enrolled in surveillance as needed. In some cases, prenatal diagnostics should be offered. In this paper, we describe the development in germline genetics of the hereditary polyposis syndromes over the last 10-12 years, their clinical characteristics, as well as how to implement genetic analyses in the diagnostic pipeline.

Selection criteria for assembling a pediatric cancer predisposition syndrome gene panel.

Increasing use of genomic sequencing enables standardized screening of all childhood cancer predisposition syndromes (CPS) in children with cancer. Gene panels currently used often include adult-onset CPS genes and genes without substantial evidence linking them to cancer predisposition. We have developed criteria to select genes relevant for childhood-onset CPS and assembled a gene panel for use in children with cancer. We applied our criteria to 381 candidate genes, which were selected through two in-house panels (n = 338), a literature search (n = 39), and by assessing two Genomics England's PanelApp panels (n = 4). We developed evaluation criteria that determined a gene's eligibility for inclusion on a childhood-onset CPS gene panel. These criteria assessed (1) relevance in childhood cancer by a minimum of five childhood cancer patients reported carrying a pathogenic variant in the gene and (2) evidence supporting a causal relation between variants in this gene and cancer development. 138 genes fulfilled the criteria. In this study we have developed criteria to compile a childhood cancer predisposition gene panel which might ultimately be used in a clinical setting, regardless of the specific type of childhood cancer. This panel will be evaluated in a prospective study. The panel is available on (pediatric-cancer-predisposition-genepanel.nl) and will be regularly updated.

Nationwide germline whole genome sequencing of 198 consecutive pediatric cancer patients reveals a high incidence of cancer prone syndromes.

PURPOSE: Historically, cancer predisposition syndromes (CPSs) were rarely established for children with cancer. This nationwide, population-based study investigated how frequently children with cancer had or were likely to have a CPS. METHODS: Children (0-17 years) in Denmark with newly diagnosed cancer were invited to participate in whole-genome sequencing of germline DNA. Suspicion of CPS was assessed according to Jongmans'/McGill Interactive Pediatric OncoGenetic Guidelines (MIPOGG) criteria and familial cancer diagnoses were verified using population-based registries. RESULTS: 198 of 235 (84.3%) eligible patients participated, of whom 94/198 (47.5%) carried pathogenic variants (PVs) in a CPS gene or had clinical features indicating CPS. Twenty-nine of 198 (14.6%) patients harbored a CPS, of whom 21/198 (10.6%) harbored a childhood-onset and 9/198 (4.5%) an adult-onset CPS. In addition, 23/198 (11.6%) patients carried a PV associated with biallelic CPS. Seven of the 54 (12.9%) patients carried two or more variants in different CPS genes. Seventy of 198 (35.4%) patients fulfilled the Jongmans' and/or MIPOGG criteria indicating an underlying CPS, including two of the 9 (22.2%) patients with an adult-onset CPS versus 18 of the 21 (85.7%) patients with a childhood-onset CPS (p = 0.0022), eight of the additional 23 (34.8%) patients with a heterozygous PV associated with biallelic CPS, and 42 patients without PVs. Children with a central nervous system (CNS) tumor had family members with CNS tumors more frequently than patients with other cancers (11/44, p = 0.04), but 42 of 44 (95.5%) cases did not have a PV in a CPS gene. CONCLUSION: These results demonstrate the value of systematically screening pediatric cancer patients for CPSs and indicate that a higher proportion of childhood cancers may be linked to predisposing germline variants than previously supposed.

Germline whole genome sequencing in pediatric oncology in Denmark-Practitioner perspectives.

BACKGROUND: With the implementation of a research project providing whole genome sequencing (WGS) to all pediatric cancer patients in Denmark (2016-2019), we sought to investigate healthcare professionals' views on WGS as it was actively being implemented in pediatric oncology. METHODS: Semistructured interviews were carried out with pediatric oncologists, clinical geneticists, and research coordinating nurses (N = 17), followed by content analysis of transcribed interviews. Interviews were supplemented by ethnographic observations on Danish pediatric oncology wards. Additionally, questionnaires were distributed to healthcare professionals concerning when they found it appropriate to approach families regarding WGS. The response rate was 74%. RESULTS: Healthcare professionals see imbalances in doctor-patient relationship, especially the double role doctors have as clinicians and researchers. Some were concerned that it might not be possible to obtain meaningful informed consent from all families following diagnosis. Still, 94% of respondents found it acceptable to approach families during the first 4 weeks from the child's diagnosis. Views on the utility of WGS, treatment adaptation, and surveillance differed among interviewees. CONCLUSION: Overall, healthcare professionals see dilemmas arising from WGS in the pediatric oncology clinic, and some advocate for further educational sessions with families and healthcare professionals. Despite concerns, healthcare professionals overwhelmingly supported early approach of families regarding WGS. Interviewees disagree on the benefits of surveillance based on genetic findings.

Pediatric cancer families' participation in whole-genome sequencing research in Denmark: Parent perspectives.

With an impending introduction of genome sequencing into paediatric oncology to facilitate personalised medicine, this study examines parent perspectives on participating in whole genome sequencing (WGS) research in the difficult weeks following diagnosis. As an embedded part of Sequencing Tumor and Germline DNA-Implications and National Guidelines (STAGING), a project aiming to implement WGS of all newly diagnosed paediatric cancer patients in Denmark, a parent perspective study was conducted by a clinical geneticist and anthropologist to document pragmatic, social and ethical dilemmas. Following genetic counselling, systematic debriefings were held and the anthropologist carried out in-depth parent interviews (N = 30 parents to 15 patients). Parents were approached about STAGING 2-28 days after diagnosis. The majority of interviewed parents reported that an early approach had been feasible for them, a few found it too early. Participation was explained in terms of altruism and a desire to learn more about why their child had developed cancer. A number of parents openly disagreed about the amount of information they wanted reported back. Enrolment in WGS research around the time of diagnosis is feasible, however, flexibility from researchers is essential. Notwithstanding high participation rates and a tendency to choose full disclosure, caution as regards the consequences of participating in WGS research is warranted.

[Germ line mutations causing paediatric cancer predisposition syndromes are common in children and adolescents with cancer].

Germ line mutations causing paediatric cancer predisposition syndromes (PCPSs) are more common than previously anticipated and are now recognised as a significant contributor to the incidence of childhood cancer. Advances in and increased clinical application of next-generation sequencing technologies have led to a rise in paediatric patients undergoing whole genome sequencing (WGS). This review focuses on the potential syndromes/diagnoses, which WGS may reveal in patients with childhood cancers, and highlights the clinical and psychosocial impact of PCPSs.

Feasibility of salivary DNA collection in a population-based case-control study: a pilot study of pediatric Crohn's disease.

BACKGROUND: Epidemiologic studies combining exposure and outcome data with the collection of biosamples are needed to study gene-environment interactions that might contribute to the etiology of complex diseases such as pediatric Crohn's disease (CD). Nationwide registries, including those in Denmark and other Scandinavian countries, provide efficient and reliable sources of data for epidemiological studies evaluating the environmental determinants of disease. We performed a pilot study to test the feasibility of collecting salivary DNA to augment registry data in established cases of pediatric CD and randomly selected, population-based controls. SUBJECTS AND METHODS: Cases of CD born after 1995 and residing in the central region of Denmark were identified through the Danish National Patient Registry and confirmed by using standard diagnostic criteria. Age- and gender-matched controls were selected at random through the civil registration system. Cases and controls were contacted by mail and telephone and invited to submit a saliva sample. DNA was extracted and genotyped for six CD-associated single-nucleotide polymorphisms (SNPs). RESULTS: A total of 53 cases of pediatric CD were invited, and 40 contributed a saliva sample (75% response rate). A total of 126 controls were invited, and 54 contributed a saliva sample (44% response rate). As expected, demographic characteristics did not differ between cases and controls. DNA was successfully isolated from 93 of 94 samples. Genotyping was performed with only 2% undetermined genotypes. For five of six SNPs known to be associated with CD, risk allele frequencies were higher in cases than controls. CONCLUSION: This pilot study strongly supports the feasibility of augmenting traditional epidemiological data from Danish population-based registries with the de novo collection of genetic information from population-based cases and controls. This will facilitate rigorous studies of gene-environment interactions in complex chronic conditions such as CD.