Increased Frequency of Clonal Hematopoiesis of Indeterminate Potential in Bloom Syndrome Probands and Carriers

Background

Bloom Syndrome (BSyn) is an autosomal recessive disorder caused by biallelic germline variants in BLM, which functions to maintain genomic stability. BSyn patients have poor growth, immune defects, insulin resistance, and a significantly increased risk of malignancies, most commonly hematologic. The malignancy risk in carriers of pathogenic variants in BLM (BLM variant carriers) remains understudied. Clonal hematopoiesis of indeterminate potential (CHIP) is defined by presence of somatic mutations in leukemia-related genes in blood of individuals without leukemia and is associated with increased risk of leukemia. We hypothesize that somatic mutations driving clonal expansion may be an underlying mechanism leading to increased cancer risk in BSyn patients and BLM variant carriers.

Methods

To determine whether de novo or somatic variation is increased in BSyn patients or carriers, we performed and analyzed exome sequencing on BSyn and control trios.

Results

We discovered that both BSyn patients and carriers had increased numbers of low-frequency, putative somatic variants in CHIP genes compared to controls. Furthermore, BLM variant carriers had increased numbers of somatic variants in DNA methylation genes compared to controls. There was no statistical difference in the numbers of de novo variants in BSyn probands compared to control probands.

Conclusion

Our findings of increased CHIP in BSyn probands and carriers suggest that one or two germline pathogenic variants in BLM could be sufficient to increase the risk of clonal hematopoiesis. These findings warrant further studies in larger cohorts to determine the significance of CHIP as a potential biomarker of aging, cancer, cardiovascular disease, morbidity and mortality.

Bloom syndrome patients and mice display accelerated epigenetic aging

Bloom syndrome (BSyn) is an autosomal recessive disorder caused by variants in the BLM gene, which is involved in genome stability. Patients with BSyn present with poor growth, sun sensitivity, mild immunodeficiency, diabetes, and increased risk of cancer, most commonly leukemias. Interestingly, patients with BSyn do not have other signs of premature aging such as early, progressive hair loss and cataracts. We set out to determine epigenetic age in BSyn, which can be a better predictor of health and disease over chronological age. Our results show for the first time that patients with BSyn have evidence of accelerated epigenetic aging across several measures in blood lymphocytes, as compared to carriers. Additionally, homozygous Blm mice exhibit accelerated methylation age in multiple tissues, including brain, blood, kidney, heart, and skin, according to the brain methylation clock. Overall, we find that Bloom syndrome is associated with accelerated epigenetic aging effects in multiple tissues and more generally a strong effect on CpG methylation levels.

An unusual presentation of bilateral optic pathway glioma in Crouzon Syndrome

Crouzon Syndrome is a genetic craniosynostosis disorder associated with a high risk of ophthalmologic sequelae secondary to structural causes. However, ophthalmologic disorders due to intrinsic nerve aberrations in Crouzon Syndrome have not been described. Optic pathway gliomas (OPGs) are low grade gliomas that are intrinsic to the visual pathway, frequently associated with Neurofibromatosis type 1 (NF-1). OPGs involving both optic nerves without affecting the optic chiasm are rarely seen outside of NF-1. We report an unusual case of bilateral optic nerve glioma without chiasmatic involvement in a 17-month-old male patient with Crouzon Syndrome without any clinical or genetic findings of NF-1. This case suggests that close ophthalmologic follow up and orbital MRIs may benefit patients with Crouzon Syndrome.

Approaches to address bias in letters of recommendation

Letters of recommendation are ubiquitous in the research enterprise. Requesting, writing, and reviewing letters of recommendation are all fraught with bias, especially for individuals from groups historically excluded from research environments. We detail how letter reviewers, requesters, and writers can make letters of recommendation a more equitable tool to evaluate scientists.

RecQ Helicase Somatic Alterations in Cancer

Named the “caretakers” of the genome, RecQ helicases function in several pathways to maintain genomic stability and repair DNA. This highly conserved family of enzymes consist of five different proteins in humans: RECQL1, BLM, WRN, RECQL4, and RECQL5. Biallelic germline mutations in BLM, WRN, and RECQL4 have been linked to rare cancer-predisposing syndromes. Emerging research has also implicated somatic alterations in RecQ helicases in a variety of cancers, including hematological malignancies, breast cancer, osteosarcoma, amongst others. These alterations in RecQ helicases, particularly overexpression, may lead to increased resistance of cancer cells to conventional chemotherapy. Downregulation of these proteins may allow for increased sensitivity to chemotherapy, and, therefore, may be important therapeutic targets. Here we provide a comprehensive review of our current understanding of the role of RecQ DNA helicases in cancer and discuss the potential therapeutic opportunities in targeting these helicases.

Neuropilin 1 regulates bone marrow vascular regeneration and hematopoietic reconstitution

Ionizing radiation and chemotherapy deplete hematopoietic stem cells and damage the vascular niche wherein hematopoietic stem cells reside. Hematopoietic stem cell regeneration requires signaling from an intact bone marrow (BM) vascular niche, but the mechanisms that control BM vascular niche regeneration are poorly understood. We report that BM vascular endothelial cells secrete semaphorin 3 A (SEMA3A) in response to myeloablation and SEMA3A induces p53 - mediated apoptosis in BM endothelial cells via signaling through its receptor, Neuropilin 1 (NRP1), and activation of cyclin dependent kinase 5. Endothelial cell - specific deletion of Nrp1 or Sema3a or administration of anti-NRP1 antibody suppresses BM endothelial cell apoptosis, accelerates BM vascular regeneration and concordantly drives hematopoietic reconstitution in irradiated mice. In response to NRP1 inhibition, BM endothelial cells increase expression and secretion of the Wnt signal amplifying protein, R spondin 2. Systemic administration of anti - R spondin 2 blocks HSC regeneration and hematopoietic reconstitution which otherwise occurrs in response to NRP1 inhibition. SEMA3A - NRP1 signaling promotes BM vascular regression following myelosuppression and therapeutic blockade of SEMA3A - NRP1 signaling in BM endothelial cells accelerates vascular and hematopoietic regeneration in vivo.

Abstract 261: Long-read sequencing characterization of a patient with bilateral Wilms tumor of unknown etiology

Wilms tumor is the most common childhood kidney cancer. 15% of patients with Wilms tumor have germline pathogenic variants in genes or regions such as WT1 or the 11p15 region. Variants in these regions can include structural or copy number alterations or alterations in methylation. In the majority of cases of Wilms tumor no known pathogenic variant could be found using the state-of-the-art technologies, including comprehensive approaches such as Illumina whole exome sequencing. One explanation for this is that such technologies have difficulties in detecting structural variants (SVs) in areas associated with repeat or low complexity sequence. In addition, Illumina technology does not immediately support direct methylation detection. Therefore, we hypothesized that analysis of bilateral Wilms tumor of unknown etiology using long-read sequencing could reveal molecular events of potential clinical interest. We performed in-depth genomic analysis on a whole blood DNA sample from a patient with a bilateral Wilms tumor. This patient had no significant family history of cancer, and previously tested negative for Beckwith-Wiedemann syndrome by methylation testing of the 11p15 region; clinical exome sequencing of the patient's germline detected no variants associated with Wilms tumors. We sequenced the genome at 40x depth using PromethION Nanopore sequencing. 29180 SVs (deletions or insertions larger than 30 base pairs) were detected using Sniffles and 26480 were detected with SVIM. Only SVs that were detected by both methods were considered for downstream analysis. Variants were annotated and filtered using a short-read catalog of SVs (gnomAD-SV), a long-read catalog, the Database of Genomic Variants catalog, and by comparison to 11 in-house genomes. We focused on SVs, copy number variants, and methylation events affecting genes previously associated with Wilms tumor. Our long-read sequencing approach detected compound heterozygotes using phased variant calls. A heterozygous missense mutation was identified in haplotype one, while a 300 base pair insertion in an ALU element was present in haplotype two. These two compound heterozygous variants overlap an exon of the OVCH2 gene, and the ALU element was not detected by the prior Illumina analysis. Additionally, we determined the frequency of methylation in CpG sites genomewide using nanopolish. Using a normal blood sample from an unrelated individual as a control, we searched for extreme differences across large and gene promoter regions. Hypermethylation in the promoter regions of genes in the 11p15.5 locus was observed in the patient as compared to the control. Hypomethylation in this region is associated with Beckwith-Wiedemann syndrome. In conclusion, nanopore technology is able to detect variants missed by Illumina sequencing, and has the potential to yield new findings of interest in a case of a child with suspected cancer predisposition syndrome.

Citation Format: Allison R. Cheney, Jean Monlong, Holly C. Beale, Hugh Olsen, Ellen Towle Kephart, Katrina Learned, Shanna White, Julian A. Martinez-Agosto, Noah Federman, Mark Akeson, Miten Jain, Vivian Y. Chang, Olena M. Vaske. Long-read sequencing characterization of a patient with bilateral Wilms tumor of unknown etiology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 261.

LGG-10. AN UNUSUAL PRESENTATION OF BILATERAL OPTIC NERVE GLIOMA IN CROUZON SYNDROME

Optic pathway gliomas (OPGs) are low grade gliomas intrinsic to the visual pathway, frequently associated with Neurofibromatosis Type 1 (NF-1). Bilateral OPGs without chiasmatic involvement are almost pathognomonic for NF-1. We report an unusual case of bilateral optic nerve glioma without chiasmatic involvement in a 17-month old male patient with craniosynostosis and Crouzon Syndrome, an autosomal dominant disorder caused by activating FGFR2 mutations associated with craniosynostosis and optic atrophy. The patient’s c.1032 G>A pathogenic variant in FGFR2 is a variant known to affect splicing and results in a protein that lacks part of an important domain involved in ligand binding. Although FGFR1 mutations have been implicated in low-grade glioma through MAPK activation, FGFR2 mutations have not yet been described in OPGs, although they have been described in epileptogenic low-grade gliomas and mixed neuronal-glial tumors. Our patient presented with worsening vision in the setting of known Crouzon Syndrome. An eye examination revealed bilateral primary optic atrophy. Brain and orbital MRIs demonstrated fusiform dilation and STIR hyperintensity of the intraorbital segments of the optic nerves bilaterally with normal pre-chiasmatic optic segments. There were no other radiographic or physical stigmata suggestive of NF-1. Next generation sequencing and copy number analysis from peripheral blood were negative for variants in NF1. RNA based studies for NF1 aberrations are pending. Although follow up MRI scans demonstrated stable size of his OPGs, the risk of further visual deficit was considered significant due to his pre-existing optic atrophy and poor baseline visual acuity. Therefore, he was started on vincristine and carboplatin chemotherapy according to A9952, and induction therapy has been well tolerated. To our knowledge, this is the first patient with Crouzon Syndrome who has developed bilateral optic pathway gliomas. Orbital MRIs should be considered for these patients with worsening visual acuity not explained by other causes.

Segmental overgrowth and aneurysms due to mosaic PDGFRB p.(Tyr562Cys)

Activating variants in the platelet-derived growth factor receptor β gene (PDGFRB) have been associated with Kosaki overgrowth syndrome, infantile myofibromatosis, and Penttinen premature aging syndrome. A recently described phenotype with fusiform aneurysm has been associated with mosaic PDGFRB c.1685A > G p.(Tyr562Cys) variant. Few reports however have examined the vascular phenotypes and mosaic effects of PDGFRB variants. We describe clinical characteristics of two patients with a recurrent mosaic PDGFRB p.(Tyr562Cys) variant identified via next-generation sequencing-based genetic testing. We observed intracranial fusiform aneurysm in one patient and found an additional eight patients with aneurysms and phenotypes associated with PDGFRB-activating variants through literature search. The conditions caused by PDGFRB-activating variants share overlapping features including overgrowth, premature aged skin, and vascular malformations including aneurysms. Aneurysms are progressive and can result in morbidities and mortalities in the absence of successful intervention. Germline and/or somatic testing for PDGFRB gene should be obtained when PDGFRB activating variant-related phenotypes are present. Whole-body imaging of the arterial tree and echocardiography are recommended after diagnosis. Repeating the imaging study within a 6- to 12-month period after detection is reasonable. Finally, further evaluation for the effectiveness and safety profile of kinase inhibitors in this patient population is warranted.

Epidermal growth factor receptor-dependent DNA repair promotes murine and human hematopoietic regeneration

Chemotherapy and irradiation cause DNA damage to hematopoietic stem cells (HSCs), leading to HSC depletion and dysfunction and the risk of malignant transformation over time. Extrinsic regulation of HSC DNA repair is not well understood, and therapies to augment HSC DNA repair following myelosuppression remain undeveloped. We report that epidermal growth factor receptor (EGFR) regulates DNA repair in HSCs following irradiation via activation of the DNA-dependent protein kinase-catalytic subunit (DNA-PKcs) and nonhomologous end joining (NHEJ). We show that hematopoietic regeneration in vivo following total body irradiation is dependent upon EGFR-mediated repair of DNA damage via activation of DNA-PKcs. Conditional deletion of EGFR in hematopoietic stem and progenitor cells (HSPCs) significantly decreased DNA-PKcs activity following irradiation, causing increased HSC DNA damage and depressed HSC recovery over time. Systemic administration of epidermal growth factor (EGF) promoted HSC DNA repair and rapid hematologic recovery in chemotherapy-treated mice and had no effect on acute myeloid leukemia growth in vivo. Further, EGF treatment drove the recovery of human HSCs capable of multilineage in vivo repopulation following radiation injury. Whole-genome sequencing analysis revealed no increase in coding region mutations in HSPCs from EGF-treated mice, but increased intergenic copy number variant mutations were detected. These studies demonstrate that EGF promotes HSC DNA repair and hematopoietic regeneration in vivo via augmentation of NHEJ. EGF has therapeutic potential to promote human hematopoietic regeneration, and further studies are warranted to assess long-term hematopoietic effects.

Mutations in the sonic hedgehog pathway cause macrocephaly-associated conditions due to crosstalk to the PI3K/AKT/mTOR pathway

The hedgehog (Hh) pathway is highly conserved and required for embryonic patterning and determination. Mutations in the Hh pathway are observed in sporadic tumors as well as under syndromic conditions. Common to these syndromes are the findings of polydactyly/syndactyly and brain overgrowth. The latter is also a finding most commonly observed in the cases of mutations in the PI3K/AKT/mTOR pathway. We have identified novel Hh pathway mutations and structural copy number variations in individuals with somatic overgrowth, macrocephaly, dysmorphic facial features, and developmental delay, which phenotypically closely resemble patients with phosphatase and tensin homolog (PTEN) mutations. We hypothesized that brain overgrowth and phenotypic overlap with syndromic overgrowth syndromes in these cases may be due to crosstalk between the Hh and PI3K/AKT/mTOR pathways. To test this, we modeled disease-associated variants by generating PTCH1 and Suppressor of Fused (SUFU) heterozygote cell lines using the CRISPR/Cas9 system. These cells demonstrate activation of PI3K signaling and increased phosphorylation of its downstream target p4EBP1 as well as a distinct cellular phenotype. To further investigate the mechanism underlying this crosstalk, we treated human neural stem cells with sonic hedgehog (SHH) ligand and performed transcriptional analysis of components of the mTOR pathway. These studies identified decreased expression of a set of mTOR negative regulators, leading to its activation. We conclude that there is a significant crosstalk between the SHH and PI3K/AKT/mTOR. We propose that this crosstalk is responsible for why mutations in PTCH1 and SUFU lead to macrocephaly phenotypes similar to those observed in PTEN hamartoma and other overgrowth syndromes associated with mutations in PI3K/AKT/mTOR pathway genes.

Burkitt-like lymphoma in a pediatric patient with familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is an autosomal dominant condition that predisposes to multiple malignancies, most commonly colorectal carcinoma, but has rarely been associated with lymphoma. We discuss one patient found to have Burkitt-like Lymphoma (BLL) with 11q aberration in the setting of previously undiagnosed FAP. We review the literature of FAP and associated malignancies and the provisional WHO classification of Burkitt-like lymphoma with 11q aberration. Both FAP and Burkitt-like lymphoma with 11q aberration involve perturbation of the MYC network and this may provide insight into a connection between these two diagnoses. However, further study is needed to elucidate if there is an increased risk of BLL and other subtypes of lymphoma among patients with FAP in order to provide optimal counseling and surveillance for patients with FAP.

CTCF variants in 39 individuals with a variable neurodevelopmental disorder broaden the mutational and clinical spectrum

Purpose

Pathogenic variants in the chromatin organizer CTCF were previously reported in seven individuals with a neurodevelopmental disorder (NDD).

Methods

Through international collaboration we collected data from 39 subjects with variants in CTCF. We performed transcriptome analysis on RNA from blood samples and utilized Drosophila melanogaster to investigate the impact of Ctcf dosage alteration on nervous system development and function.

Results

The individuals in our cohort carried 2 deletions, 8 likely gene-disruptive, 2 splice-site, and 20 different missense variants, most of them de novo. Two cases were familial. The associated phenotype was of variable severity extending from mild developmental delay or normal IQ to severe intellectual disability. Feeding difficulties and behavioral abnormalities were common, and variable other findings including growth restriction and cardiac defects were observed. RNA-sequencing in five individuals identified 3828 deregulated genes enriched for known NDD genes and biological processes such as transcriptional regulation. Ctcf dosage alteration in Drosophila resulted in impaired gross neurological functioning and learning and memory deficits.

Conclusion

We significantly broaden the mutational and clinical spectrum ofCTCF-associated NDDs. Our data shed light onto the functional role of CTCF by identifying deregulated genes and show that Ctcf alterations result in nervous system defects in Drosophila.

Is polycystic kidney disease associated with malignancy in children?

Background

Polycystic kidney disease (PKD) is an inherited condition characterized by progressive development of end‐stage renal disease, hypertension, hepatic fibrosis, and cysts in the kidney, liver, pancreas, spleen, thyroid, and epididymis. While malignancies have been reported in association with PKD in adults, the incidence of malignancies in children with PKD is not currently known.

Methods

We report on five patients with a known history of PKD who developed a malignancy as children at the University of California, Los Angeles and the University of Colorado Anschutz Medical Campus. Patients were included from 2012 to 2017.

Results

We present five patients with a history of PKD diagnosed with a malignancy during childhood without any additional known mutations to suggest a genetic predisposition to develop cancer. This includes the first reported case of hepatocellular carcinoma in a patient with autosomal recessive polycystic kidney disease.

Conclusion

Our report illustrates the potential that PKD may be associated with an increased risk for developing cancer, even in children. Further research is necessary to better understand this relationship.

Pharmacogenetics of Chemotherapy-Induced Cardiotoxicity

PURPOSE OF REVIEW

The goal of this review is to summarize current understanding of pharmacogenetics and pharmacogenomics in chemotherapy-induced cardiotoxicity.

RECENT FINDINGS

Most of the studies rely on in vitro cytotoxic assays. There have been several smaller scale candidate gene approaches and a handful of genome-wide studies linking genetic variation to susceptibility to chemotherapy-induced cardiotoxicity. Currently, pharmacogenomic testing of all childhood cancer patients with an indication for doxorubicin or daunorubicin therapy for RARG rs2229774, SLC28A3 rs7853758, and UGT1A6*4 rs17863783 variants is recommended. There is no recommendation regarding testing in adults. There is clear evidence pointing to the role of pharmacogenetics and pharmacogenomics in cardiotoxicity susceptibility to chemotherapeutic agents. Larger scale studies are needed to further identify susceptibility markers and to develop pharmacogenomics-based risk profiling to improve quality of life and life expectancy in cancer survivors.

Cancer and Central Nervous System Tumor Surveillance in Pediatric Neurofibromatosis 1

Although the neurofibromatoses consist of at least three autosomal dominantly inherited disorders, neurofibromatosis 1 (NF1), neurofibromatosis 2 (NF2), and schwannomatosis, NF1 represents a multisystem pleiotropic condition very different from the other two. NF1 is a genetic syndrome first manifesting in childhood; affecting multiple organs, childhood development, and neurocognitive status; and presenting the clinician with often complex management decisions that require a multidisciplinary approach. Molecular genetic testing (see article for detailed discussion) is recommended to confirm NF1, particularly in children fulfilling only pigmentary features of the diagnostic criteria. Although cancer risk is not the major issue facing an individual with NF1 during childhood, the condition causes significantly increased malignancy risks compared with the general population. Specifically, NF1 is associated with highly elevated risks of juvenile myelomonocytic leukemia, rhabdomyosarcoma, and malignant peripheral nerve sheath tumor as well as substantial risks of noninvasive pilocytic astrocytoma, particularly optic pathway glioma (OPG), which represent a major management issue. Until 8 years of age, clinical assessment for OPG is advised every 6 to 12 months, but routine MRI assessment is not currently advised in asymptomatic individuals with NF1 and no signs of clinical visual pathway disturbance. Routine surveillance for other malignancies is not recommended, but clinicians and parents should be aware of the small risks (<1%) of certain specific individual malignancies (e.g., rhabdomyosarcoma). Tumors do contribute to both morbidity and mortality, especially later in life. A single whole-body MRI should be considered at transition to adulthood to assist in determining approaches to long-term follow-up. Clin Cancer Res; 23(12); e46-e53. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Cancer and Central Nervous System Tumor Surveillance in Pediatric Neurofibromatosis 2 and Related Disorders

The neurofibromatoses consist of at least three autosomal-dominant inherited disorders: neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis. For over 80 years, these conditions were inextricably tied together under generalized neurofibromatosis. In 1987, the localization of NF1 to chromosome 17q and NF2 (bilateral vestibular schwannoma) to 22q led to a consensus conference at Bethesda, Maryland. The two main neurofibromatoses, NF1 and NF2, were formally separated. More recently, the SMARCB1 and LZTR1 genes on 22q have been confirmed as causing a subset of schwannomatosis. The last 26 years have seen a great improvement in understanding of the clinical and molecular features of these conditions as well as insights into management. Childhood presentation of NF2 (often with meningioma) in particular predicts a severe multitumor disease course. Malignancy is rare in NF2, particularly in childhood; however, there are substantial risks from benign and low-grade central nervous system (CNS) tumors necessitating MRI surveillance to optimize management. At least annual brain MRI, including high-resolution images through the auditory meatus, and a clinical examination and auditory assessment are required from diagnosis or from around 10 to 12 years of age if asymptomatic. Spinal imaging at baseline and every 2 to 3 years is advised with more frequent imaging if warranted on the basis of sites of tumor involvement. The malignancy risk in schwannomatosis is not well defined but may include an increased risk of malignant peripheral nerve sheath tumor in SMARCB1 Imaging protocols are also proposed for SMARCB1 and LZTR1 schwannomatosis and SMARCE1-related meningioma predisposition. Clin Cancer Res; 23(12); e54-e61. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Young endothelial cells revive aging blood

The hematopoietic system declines with age, resulting in decreased hematopoietic stem cell (HSC) self-renewal capacity, myeloid skewing, and immune cell depletion. Aging of the hematopoietic system is associated with an increased incidence of myeloid malignancies and a decline in adaptive immunity. Therefore, strategies to rejuvenate the hematopoietic system have important clinical implications. In this issue of the JCI, Poulos and colleagues demonstrate that infusions of bone marrow (BM) endothelial cells (ECs) from young mice promoted HSC self-renewal and restored immune cell content in aged mice. Additionally, delivery of young BM ECs along with HSCs following total body irradiation improved HSC engraftment and enhanced survival. These results suggest an important role for BM endothelial cells (ECs) in regulating hematopoietic aging and support further research to identify the rejuvenating factors elaborated by BM ECs that restore HSC function and the immune repertoire in aged mice.

Recommendations for Childhood Cancer Screening and Surveillance in DNA Repair Disorders

DNA repair syndromes are heterogeneous disorders caused by pathogenic variants in genes encoding proteins key in DNA replication and/or the cellular response to DNA damage. The majority of these syndromes are inherited in an autosomal-recessive manner, but autosomal-dominant and X-linked recessive disorders also exist. The clinical features of patients with DNA repair syndromes are highly varied and dependent on the underlying genetic cause. Notably, all patients have elevated risks of syndrome-associated cancers, and many of these cancers present in childhood. Although it is clear that the risk of cancer is increased, there are limited data defining the true incidence of cancer and almost no evidence-based approaches to cancer surveillance in patients with DNA repair disorders. This article is the product of the October 2016 AACR Childhood Cancer Predisposition Workshop, which brought together experts from around the world to discuss and develop cancer surveillance guidelines for children with cancer-prone disorders. Herein, we focus on the more common of the rare DNA repair disorders: ataxia telangiectasia, Bloom syndrome, Fanconi anemia, dyskeratosis congenita, Nijmegen breakage syndrome, Rothmund-Thomson syndrome, and Xeroderma pigmentosum. Dedicated syndrome registries and a combination of basic science and clinical research have led to important insights into the underlying biology of these disorders. Given the rarity of these disorders, it is recommended that centralized centers of excellence be involved directly or through consultation in caring for patients with heritable DNA repair syndromes. Clin Cancer Res; 23(11); e23-e31. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Novel association of familial testicular germ cell tumor and autosomal dominant polycystic kidney disease with PKD1 mutation

Adolescent brothers were diagnosed with testicular germ cell tumors within the same month. Both were found to have multiple renal cysts on pretreatment imaging done for staging. The proband, his brother, and their mother, were all found to have a novel splice variant in intron 8 of the PKD1 gene by clinical exome sequencing. This is the second family reported with both familial testicular germ cell tumor (FTGCT) and autosomal dominant polycystic kidney disease (ADPKD), and the first described association of FTGCT with a splice variant in PKD1. We suggest that this novel variant in PKD1 may convey increased risk for FTGCT in addition to causing ADPKD.

Optimizing Combination Therapy for Acute Lymphoblastic Leukemia Using a Phenotypic Personalized Medicine Digital Health Platform: Retrospective Optimization Individualizes Patient Regimens to Maximize Efficacy and Safety

Acute lymphoblastic leukemia (ALL) is a blood cancer that is characterized by the overproduction of lymphoblasts in the bone marrow. Treatment for pediatric ALL typically uses combination chemotherapy in phases, including a prolonged maintenance phase with oral methotrexate and 6-mercaptopurine, which often requires dose adjustment to balance side effects and efficacy. However, a major challenge confronting combination therapy for virtually every disease indication is the inability to pinpoint drug doses that are optimized for each patient, and the ability to adaptively and continuously optimize these doses to address comorbidities and other patient-specific physiological changes. To address this challenge, we developed a powerful digital health technology platform based on phenotypic personalized medicine (PPM). PPM identifies patient-specific maps that parabolically correlate drug inputs with phenotypic outputs. In a disease mechanism-independent fashion, we individualized drug ratios/dosages for two pediatric patients with standard-risk ALL in this study via PPM-mediated retrospective optimization. PPM optimization demonstrated that dynamically adjusted dosing of combination chemotherapy could enhance treatment outcomes while also substantially reducing the amount of chemotherapy administered. This may lead to more effective maintenance therapy, with the potential for shortening duration and reducing the risk of serious side effects.

Childhood Exposures and Risk of Malignancy in Adulthood

Pediatricians have significant roles in preventive health care, and understanding how various exposures during childhood can have long-lasting effects on cancer risk is critical in promoting future health. With the exception of rare genetic syndromes conferring increased cancer susceptibility, most cancers are considered idiopathic and may be influenced by modifiable exposures and risks. This review aims to serve as a brief overview of a subset of known exposures during childhood that have been associated with an increased risk of malignancy in adulthood, including the effects of radiation, chemotherapy, pesticides, nutrition, puberty, and infection.

Clinical exome sequencing for genetic identification of rare Mendelian disorders

IMPORTANCE

Clinical exome sequencing (CES) is rapidly becoming a common molecular diagnostic test for individuals with rare genetic disorders.

OBJECTIVE

To report on initial clinical indications for CES referrals and molecular diagnostic rates for different indications and for different test types.

DESIGN, SETTING, AND PARTICIPANTS

Clinical exome sequencing was performed on 814 consecutive patients with undiagnosed, suspected genetic conditions at the University of California, Los Angeles, Clinical Genomics Center between January 2012 and August 2014. Clinical exome sequencing was conducted as trio-CES (both parents and their affected child sequenced simultaneously) to effectively detect de novo and compound heterozygous variants or as proband-CES (only the affected individual sequenced) when parental samples were not available.

MAIN OUTCOMES AND MEASURES

Clinical indications for CES requests, molecular diagnostic rates of CES overall and for phenotypic subgroups, and differences in molecular diagnostic rates between trio-CES and proband-CES.

RESULTS

Of the 814 cases, the overall molecular diagnosis rate was 26% (213 of 814; 95% CI, 23%-29%). The molecular diagnosis rate for trio-CES was 31% (127 of 410 cases; 95% CI, 27%-36%) and 22% (74 of 338 cases; 95% CI, 18%-27%) for proband-CES. In cases of developmental delay in children (<5 years, n = 138), the molecular diagnosis rate was 41% (45 of 109; 95% CI, 32%-51%) for trio-CES cases and 9% (2 of 23, 95% CI, 1%-28%) for proband-CES cases. The significantly higher diagnostic yield (P value = .002; odds ratio, 7.4 [95% CI, 1.6-33.1]) of trio-CES was due to the identification of de novo and compound heterozygous variants.

CONCLUSIONS AND RELEVANCE

In this sample of patients with undiagnosed, suspected genetic conditions, trio-CES was associated with higher molecular diagnostic yield than proband-CES or traditional molecular diagnostic methods. Additional studies designed to validate these findings and to explore the effect of this approach on clinical and economic outcomes are warranted.

Expanding the mutational spectrum of LZTR1 in schwannomatosis

Schwannomatosis is characterized by the development of multiple non-vestibular, non-intradermal schwannomas. Constitutional inactivating variants in two genes, SMARCB1 and, very recently, LZTR1, have been reported. We performed exome sequencing of 13 schwannomatosis patients from 11 families without SMARCB1 deleterious variants. We identified four individuals with heterozygous loss-of-function variants in LZTR1. Sequencing of the germline of 60 additional patients identified 18 additional heterozygous variants in LZTR1. We identified LZTR1 variants in 43% and 30% of familial (three of the seven families) and sporadic patients, respectively. In addition, we tested LZTR1 protein immunostaining in 22 tumors from nine unrelated patients with and without LZTR1 deleterious variants. Tumors from individuals with LZTR1 variants lost the protein expression in at least a subset of tumor cells, consistent with a tumor suppressor mechanism. In conclusion, our study demonstrates that molecular analysis of LZTR1 may contribute to the molecular characterization of schwannomatosis patients, in addition to NF2 mutational analysis and the detection of chromosome 22 losses in tumor tissue. It will be especially useful in differentiating schwannomatosis from mosaic Neurofibromatosis type 2 (NF2). However, the role of LZTR1 in the pathogenesis of schwannomatosis needs further elucidation.

Whole exome sequencing of pediatric gastric adenocarcinoma reveals an atypical presentation of Li-Fraumeni syndrome

BACKGROUND

Gastric adenocarcinoma is a rare diagnosis in childhood. A 14-year-old male patient presented with metastatic gastric adenocarcinoma, and a strong family history of colon cancer. Clinical sequencing of CDH1 and APC were negative. Whole exome sequencing was therefore applied to capture the majority of protein-coding regions for the identification of single-nucleotide variants, small insertion/deletions, and copy number abnormalities in the patient's germline as well as primary tumor.

MATERIALS AND METHODS

DNA was extracted from the patient's blood, primary tumor, and the unaffected mother's blood. DNA libraries were constructed and sequenced on Illumina HiSeq2000. Data were post-processed using Picard and Samtools, then analyzed with the Genome Analysis Toolkit. Variants were annotated using an in-house Ensembl-based program. Copy number was assessed using ExomeCNV.

RESULTS

Each sample was sequenced to a mean depth of coverage of greater than 120×. A rare non-synonymous coding single-nucleotide variant (SNV) in TP53 was identified in the germline. There were 10 somatic cancer protein-damaging variants that were not observed in the unaffected mother genome. ExomeCNV comparing tumor to the patient's germline, identified abnormal copy number, spanning 6,946 genes.

CONCLUSION

We present an unusual case of Li-Fraumeni detected by whole exome sequencing. There were also likely driver somatic mutations in the gastric adenocarcinoma. These results highlight the need for more thorough and broad scale germline and cancer analyses to accurately inform patients of inherited risk to cancer and to identify somatic mutations.

Coexistence of translocation(1,19) and the Philadelphia chromosome in a child's first presentation of chronic myeloid leukemia in blast crisis treated with dasatinib

Chronic myelogenous leukemia (CML) constitutes less than 5% of childhood leukemias. The authors describe a rare case of a 14-year-old boy who presented with CML in blast crisis. Unique to this patient was the evidence of both breakpoint cluster region-c-abl oncogene 1 (BCR-ABL1) fusions as well as an additional unbalanced t(1;19) translocation. This combination has not previously been reported in the same patient. Initial treatment with dasatinib achieved a complete cytogenetic response within 2 months of therapy. This case highlights the heterogeneous presentation of CML in children and rationale for use of dasatinib as a first-line agent for patients with blast crisis.

B-acute lymphoblastic leukemia and cystinuria in a patient with duplication 22q11.21 detected by chromosomal microarray analysis

Duplication 22q11.2 syndrome is the result of a microduplication of the same chromosomal region that is deleted in DiGeorge and Velocardiofacial syndromes. We describe a patient with dysmorphic features who was diagnosed with pre-B acute lymphoblastic leukemia, and developed cystinuria and pancreatitis during treatment. Duplication 22q11.2 has not been previously described in association with hematologic abnormalities. Chromosomal microarray technology was used to diagnose duplication 22q11.2 syndrome. In this era of advanced genomics, this technology has become an important method for helping to determine the molecular basis of diseases, best treatments and ultimately patient outcomes.

Interns overestimate the effectiveness of their hand-off communication

OBJECTIVE

Theories from the psychology of communication may be applicable in understanding why hand-off communication is inherently problematic. The purpose of this study was to assess whether postcall pediatric interns can correctly estimate the patient care information and rationale received by on-call interns during hand-off communication.

METHODS

Pediatric interns at the University of Chicago were interviewed about the hand-off. Postcall interns were asked to predict what on-call interns would report as the important pieces of information communicated during the hand-off about each patient, with accompanying rationale. Postcall interns also guessed on-call interns' rating of how well the hand-offs went. Then, on-call interns were asked to list the most important pieces of information for each patient that postcall interns communicated during the hand-off, with accompanying rationale. On-call interns also rated how well the hand-offs went. Interns had access to written hand-offs during the interviews.

RESULTS

We conducted 52 interviews, which constituted 59% of eligible interviews. Seventy-two patients were discussed. The most important piece of information about a patient was not successfully communicated 60% of the time, despite the postcall intern's believing that it was communicated. Postcall and on-call interns did not agree on the rationales provided for 60% of items. In addition, an item was more likely to be effectively communicated when it was a to-do item (65%) or an item related to anticipatory guidance (69%) compared with a knowledge item (38%). Despite the lack of agreement on content and rationale of information communicated during hand-offs, peer ratings of hand-off quality were high.

CONCLUSIONS

Pediatric interns overestimated the effectiveness of their hand-off communication. Theories from communication psychology suggest that miscommunication is caused by egocentric thought processes and a tendency for the speaker to overestimate the receiver's understanding. This study demonstrates that systematic causes of miscommunication may play a role in hand-off quality.

The effects of on-duty napping on intern sleep time and fatigue

BACKGROUND

Naps during extended work shifts are effective in reducing fatigue in other industries, but the use of a nap as a countermeasure to prevent fatigue in residents is uncertain.

OBJECTIVE

To assess the effects of a call-night nap on resident sleep and fatigue.

DESIGN

1-year, within-participant, paired trial with crossover at midmonth.

SETTING

Academic teaching hospital.

PARTICIPANTS

38 of 40 internal medicine interns.

MEASUREMENTS

Sleep was measured by using wristwatch actigraphy. By using the experience sampling method on a personal digital assistant, random alerts prompted interns to rate fatigue on the 7-point Stanford Sleepiness Scale (7 is most tired). Hospital paging logs and structured interviews provided information on use of coverage.

INTERVENTION

For 2 weeks of every month, interns were assigned to the nap schedule, which provided coverage to on-duty interns from midnight to 7:00 a.m. so that they could finish their work and take a nap. The other 2 weeks of the month constituted a standard schedule.

RESULTS

Interns received 41 more minutes of sleep while on call with the nap schedule (185 minutes vs. 144 minutes; P < 0.001). When interns with the nap schedule used coverage, they received 68 more minutes of sleep (210 minutes vs. 142 minutes; P < 0.001). Despite these small increases in sleep, interns reported less overall fatigue while on the nap schedule than while on the standard schedule (1.74 vs. 2.26; P = 0.017). Postcall fatigue with the nap schedule was lower by nearly 1 point (2.23 vs 3.16; P = 0.036), which is almost equivalent to the difference between on-call and postcall fatigue with the standard schedule (2.06 vs. 3.16). However, use of coverage by interns on the nap schedule was impaired by their desire to care for their patients and concerns about discontinuity of care.

LIMITATIONS

This was a single-institution study that did not have the power to examine outcomes related to intern or patient well-being.

CONCLUSIONS

Coverage to allow a nap during an extended duty-hour shift can increase sleep and decrease fatigue for residents.

Experience-dependent modulation of motor corticospinal excitability during action observation

The primate premotor cortex is endowed with an "action observation/execution matching system", that is, the same premotor neurons discharge when actions are performed and when actions are observed. Hence, this system predicts a strong visual input to the motor system. Whether this input is dependent on visual experience or not has not been previously investigated. To address this issue we compared corticospinal excitability while subjects viewed frequently observed and less frequently observed hand actions of others and of themselves. Motor corticospinal excitability was larger when the action orientations were as they are frequently observed (Self-away, subject's own hand facing out from the subject, or Other-toward, an unknown hand facing toward the subject) compared with less frequently observed actions (Self-toward, subject's own hand facing "toward" the subject, or Other-away, an unknown hand facing out from the subject). This finding suggests that the modulation of motor corticospinal excitability during action observation and hence the "action observation/execution matching system" is largely dependent upon visual experience.