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A novel group of S100- and CD34-positive spindle cell tumors with distinctive stromal and perivascular hyalinization harboring recurrent gene fusions involving kinases including RAF1, BRAF, NTRK1/2/3, and RET have been recently reported. To our knowledge, no such cases harboring ALK rearrangements have been identified. We report a previously healthy 41-year-old male with a 12-cm intramuscular shoulder mass. The tumor was composed of bland-appearing spindled to epithelioid cells, arranged in a patternless pattern in a background of loose myxoid stroma containing striking amianthoid-like stromal collagen and perivascular rings. In accordance with the previously reported tumors, the tumor cells showed diffuse immunopositivity with S100 and CD34, while lacking SOX10 expression. Targeted RNA-based next-generation sequencing identified a novel serine/threonine-protein phosphatase PP1-beta-catalytic subunit (PPP1CB)-ALK fusion gene. Although ALK break-apart was not detected by FISH, likely due to a paracentric inversion of chromosome 2, the presence of the fusion was confirmed by Sanger sequencing showing a 10-bp linker between exon 6 of PPP1CB and intron 19 of ALK while maintaining reading frame. Subsequent ALK-1 immunostain exhibited diffuse cytoplasmic staining in the tumor cells. Our case expands the molecular genetic spectrum of the distinctive group of spindle cell tumors with CD34/S100+ immunophenotype, supporting the important role of various kinases as drivers of oncogenesis. Awareness of this entity including its unique morphologic and immunophenotypic features as well as its interchangeable kinase gene fusions is crucial for correct classification and potential targeted therapy, particularly in aggressive subsets.

Context.— Next-generation sequencing–based assays are being increasingly used in the clinical setting for the detection of somatic variants in solid tumors, but limited data are available regarding the interlaboratory performance of these assays. Objective.— To examine proficiency testing data from the initial College of American Pathologists (CAP) Next-Generation Sequencing Solid Tumor survey to report on laboratory performance. Design.— CAP proficiency testing results from 111 laboratories were analyzed for accuracy and associated assay performance characteristics. Results.— The overall accuracy observed for all variants was 98.3%. Rare false-negative results could not be attributed to sequencing platform, selection method, or other assay characteristics. The median and average of the variant allele fractions reported by the laboratories were within 10% of those orthogonally determined by digital polymerase chain reaction for each variant. The median coverage reported at the variant sites ranged from 1922 to 3297. Conclusions.— Laboratories demonstrated an overall accuracy of greater than 98% with high specificity when examining 10 clinically relevant somatic single-nucleotide variants with a variant allele fraction of 15% or greater. These initial data suggest excellent performance, but further ongoing studies are needed to evaluate the performance of lower variant allele fractions and additional variant types.

CONTEXT: In adults, noninvasive follicular variant of papillary thyroid carcinoma (FVPTC) is considered a low risk for metastasis and persistent/recurrent disease. OBJECTIVE: The goal of this study was to assess the clinical, sonographic, and histopathologic features of FVPTC in a pediatric cohort. DESIGN: A retrospective review of subjects

Background: Inhibition of the WEE1 kinase by adavosertib (AZD1775) potentiates replicative stress from genomic instability or chemotherapy, and demonstrated anti-tumor activity in preclinical models of pediatric cancer. This study reports the phase 2 expansion of the ADVL1312 phase I/II trial combining irinotecan and adavosertib in children and adolescents with relapsed/refractory solid and CNS tumors. Methods: Patients (< 21 yrs old) with measurable or MIBG-evaluable relapsed/refractory neuroblastoma (Part B), medulloblastoma/CNS embryonal tumors (Part C) or rhabdomyosarcoma (Part D) were treated with irinotecan (90 mg/m2/dose) and adavosertib (85 mg/m2/dose) orally for 5-days every 21-days. Any patient who received at least one dose was considered evaluable for response. Using a Simon's two stage design the combination was considered effective if there were three out of twenty responses in parts B and D or six out of nineteen responses in part C. Tumor tissue was analyzed for ATRX deficiency by multiplex immunofluorescence of ultrabright telomere foci and ATRX, and where available, prior tumor genomic analyses. Results: Twenty eligible patients with neuroblastoma, with a median age of nine years old (6-19) were included in Part B. They had a median of three prior chemotherapy regimens (1-7); nineteen patients (95%) had prior irinotecan and seventeen (85%) received prior radiation therapy. The combination therapy resulted in three objective responses confirmed by central review (estimated response rate of 16.7%) meeting the protocol defined efficacy endpoint for Part B. The responses included a measurable partial response (11 cycles), MIBG evaluable complete response (9 cycles) and MIBG and marrow evaluable partial response (18 cycles). In addition, there were three patients with prolonged stable disease of 8, 11 and 13 cycles. Two of the three patients with objective responses had tumors with predicted ATRX deficiency, while the third did not have available archival tumor. Of the nine neuroblastoma patient tumors with predicted ATRX deficiency, 4 (44%) had objective responses or prolonged stable disease. In part C, of 9 patients eligible for response, 1 patient with pineoblastoma had a confirmed partial response (9 cycles) and another with medulloblastoma had prolonged stable disease (11 cycles). In part D, of 10 eligible patients, 2 had stable disease of 8 and 10 cycles. Part C and D did not meet the protocol defined efficacy endpoint. The combination was well tolerated with one patient experiencing a dose limiting toxicity that resolved with dose reduction. Conclusion: This the first phase 2 clinical trial of adavosertib in pediatrics and the first in combination with irinotecan. The combination was of sufficient activity to support further study in neuroblastoma, and possibly other pediatric tumor types with recurrent ATRX mutation. Citation Format: Kristina A. Cole, Heba Ijaz, Lea Surrey, Mariarita Santi-vicini, Xiaowei Liu, Charles G. Minard, John M. Maris, Stephan Voss, Elizabeth Fox, Brenda Weigal. Pediatric phase 2 trial of the WEE1 inhibitor adavosertib (AZD1775) and irinotecan: A Children's Oncology Group Study (ADVL1312) [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 CT029.

Dysembryoplastic neuroepithelial tumors (DNT) lacking key diagnostic criteria are challenging to diagnose and sometimes fall into the broader category of mixed neuronal-glial tumors (MNGT) or the recently described polymorphous low-grade neuroepithelial tumor of the young (PLNTY). We examined 41 patients with DNT, MNGT, or PLNTY for histologic features, genomic findings, and progression-free survival (PFS). Genomic analysis included sequence and copy number variants and RNA-sequencing. Classic DNT (n = 26) was compared with those with diffuse growth without cortical nodules (n = 15), 6 of which exhibited impressive CD34 staining classifying them as PLNTY. Genomic analysis was complete in 33, with sequence alterations recurrently identified in BRAF, FGFR1, NF1, and PDGFRA, as well as 7 fusion genes involving FGFR2, FGFR1, NTRK2, and BRAF. Genetic alterations did not distinguish between MNGTs, DNTs, or PLNTYs; however, FGFR1 alterations were confined to DNT, and PLNTYs contained BRAF V600E or FGFR2 fusion genes. Analysis of PFS showed no significant difference by histology or genetic alteration; however, numbers were small and follow-up time short. Further molecular characterization of a PLNTY-related gene fusion, FGFR2-CTNNA3, demonstrated oncogenic potential via MAPK/PI3K/mTOR pathway activation. Overall, DNT-MNGT spectrum tumors exhibit diverse genomic alterations, with more than half (19/33) leading to MAPK/PI3K pathway alterations.

Introduction: The American Joint Committee Cancer (AJCC) TNM system predicts survival in patients with differentiated thyroid cancer (DTC). In the eighth edition of the AJCC TNM, microscopic extrat...

Sclerosing epithelioid fibrosarcoma (SEF) is an uncommon neoplasm that rarely presents in bone. It is characterized by epithelioid cells arranged in nests and single-file cords within a sclerotic stromal background which may mimic neoplastic bone. SEF harbors an EWSR1 translocation, which may complicate its distinction from Ewing sarcoma in cases with histomorphologic overlap. We present a diagnostically challenging case of SEF in the mandible of a 16-year-old girl. Our experience highlights the lack of specificity of traditional morphology and EWSR1 break-apart fluorescent in situ hybridization. Open-ended RNA-based fusion gene testing coupled with MUC4 immunohistochemistry aided the eventual diagnosis in this case. Herein, we report the third case of SEF with EWSR1-CREB3L3 translocation and show that this fusion leads to aberrant upregulation of the phosphoinositide 3-kinase/mammalian target of rapamycin signaling pathway in heterologous cell models.

Background Liver fibrosis is a serious complication of single ventricle Fontan survivors. Its causes are of great interest, and potential solutions to halt or delay progression are needed. The purpose of this study is to investigate if prior hemodynamics and anatomy can predict liver fibrosis severity in these patients. Methods Twenty-one Fontan patients with cardiac magnetic resonance (CMR) data obtained greater than 1 year before liver biopsy data were included. Computational fluid dynamic simulations were performed to quantify total cavopulmonary connection (TCPC) flow dynamics using patient-specific anatomies and blood flow waveforms reconstructed from CMR data. Collagen deposition (a measure of liver fibrosis) was quantified by digital image analysis of Sirius red–stained slides. Statistical analyses were performed to investigate potential relationships between Fontan hemodynamics and liver fibrosis. Results With an average time of 6.7 ± 2.9 years (range, 2-11 years) between CMR and biopsy, TCPC resistance and left pulmonary artery stenosis showed significant, positive correlations with magnitude of liver fibrosis (r = 0.54, P = .026; and r = 0.55, P = .028, respectively). The change in inferior vena cava flow rate over time also showed a significant positive correlation with magnitude of liver fibrosis (r = 0.91, P = .001). Conclusions TCPC resistance, left pulmonary artery stenosis, and increased inferior vena cava flow are positively associated with liver fibrosis after Fontan operation and hold promise as important predictors of hepatic decline. These findings encourage preprocedural planning and interventional strategies to improve TCPC performance and reduce vessel stenosis. Further investigation is warranted to design the ideal Fontan circulation and optimize flow dynamics to reduce the risk of liver fibrosis.

Classic dysembryoplastic neuroepithelial tumor (DNT) is a low-grade pediatric neoplasm defined histologically by specific glioneuronal elements with mucin-matrix floating neurons. However, many tumors preclude confident morphologic classification and are better designated as mixed neuronal-glial tumors (MNGTs). To determine if a molecular signature is associated with classic DNT morphology, we retrospectively examined the histological, genetic and molecular profile of a DNT/MNGT cohort. In this multi-institutional study, 34 patients with DNT (11) and MNGT (23) were included. Methodology included combinations of fusion detection by anchored multiplex PCR or RNA sequencing, sequence alterations in 238 cancer gene panel or whole genome by next generation sequencing (NGS), and copy number variants (CNVs) by genome wide array or NGS. A novel fusion was characterized by generating NIH3T3 stable cells for pathway analysis and transformation assays. Based on genetic profiles, tumors were classified as follows: ‘BRAF-altered’ included 23% (8/34) with BRAF V600E or BRAF-fusions; ‘FGFR-altered’ included 20.5% (7/34), where we further characterized the rare FGFR2-CTNNA3 fusion; ‘Other alteration’ encompassed 26% (9/34) with NTRK2 fusion, KDM5C and PDGFRA mutations or CNVs; ‘no alteration’ included 29% (10/34) with no known pathogenic mutations (variants of unknown significance excluded). Three patients had potential cancer predisposition syndromes (ATMx2, NF1). In cell models, FGFR2-CTNNA3 was an oncogenic driver activating MAPK/PI3K pathways. Overall, we found genetic alterations affecting MAPK/PI3K pathways in 44% (15/34) of tumors, including 20.5% with gene fusions. Given the spectrum of abnormalities and small cohort size, a definitive genetic profile distinguishing classic DNT from MNGT was not identified. However, all the BRAF-altered cases exhibited MNGT histology, whereas the other 3 sub-groups spanned both histologies. The BRAF-altered group also showed recurrence free survival (maximum follow-up of 60 months). This study highlights the genetic diversity prevalent across DNT/MNGT and the difficulty of assigning a molecular classifier to this tumor group.

There has been a rapid expansion of next-generation sequencing (NGS)-based assays for the detection of somatic variants in solid tumors. However, limited data are available regarding the comparative performance of NGS and non-NGS assays using standardized samples across a large number of laboratories.To compare the performance of NGS and non-NGS assays using well-characterized proficiency testing samples provided by the College of American Pathologists (CAP) Molecular Oncology Committee. A secondary goal was to compare the use of preanalytic and postanalytic practices.A total of 17 343 responses were obtained from participants in theWhile both NGS and non-NGS achieved an acceptable response rate of greater than 95%, the overall performance of NGS methods was significantly better than that of non-NGS methods for the identification of variants inThe overall analytic performance of both methods was excellent. For specific

Gene fusions are one of the most common genomic alterations in pediatric cancer. Many fusions encode oncogenic drivers and play important roles in cancer diagnosis, risk stratification, and treatment selection. We report the development and clinical validation of a large custom-designed RNA sequencing panel, CHOP Fusion panel, using anchored multiplex PCR technology. The panel interrogates 106 cancer genes known to be involved in nearly 600 different fusions reported in hematological malignancies and solid tumors. The panel works well with different types of samples, including formalin-fixed, paraffin-embedded samples. The panel demonstrated excellent analytic accuracy, with 100% sensitivity and specificity on 60 pediatric tumor validation samples. In addition to identifying all known fusions in the validation samples, three unrecognized, yet clinically significant, fusions were also detected. A total of 276 clinical cases were analyzed after the validation, and 51 different fusions were identified in 104 cases. Of these fusions, 16 were not previously reported at the time of discovery. These fusions provided genomic information useful for clinical management. Our experience demonstrates that CHOP Fusion panel can detect the vast majority of known and certain novel clinically relevant fusion genes in pediatric cancers accurately, efficiently, and cost-effectively; and the panel provides an excellent tool for new fusion gene discovery.

Item does not contain fulltext Haploinsufficiency of FOXF1 causes alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV), a lethal neonatal lung developmental disorder. We describe two similar heterozygous CNV deletions involving the FOXF1 enhancer and re-analyze FOXF1 missense mutation, all associated with an unexpectedly mitigated disease phenotype. In one case, the deletion of the maternal allele of the FOXF1 enhancer caused pulmonary hypertension and histopathologically diagnosed MPV without the typical ACD features. In the second case, the deletion of the paternal enhancer resulted in ACDMPV rather than the expected neonatal lethality. In both cases, FOXF1 expression in lung tissue was higher than usually seen or expected in patients with similar deletions, suggesting an increased activity of the remaining allele of the enhancer. Sequencing of these alleles revealed two rare SNVs, rs150502618-A and rs79301423-T, mapping to the partially overlapping binding sites for TFAP2s and CTCF in the core region of the enhancer. Moreover, in a family with three histopathologically-diagnosed ACDMPV siblings whose missense FOXF1 mutation was inherited from the healthy non-mosaic carrier mother, we have identified a rare SNV rs28571077-A within 2-kb of the above-mentioned non-coding SNVs in the FOXF1 enhancer in the mother, that was absent in the affected newborns and 13 unrelated ACDMPV patients with CNV deletions of this genomic region. Based on the low population frequencies of these three variants, their absence in ACDMPV patients, the results of reporter assay, RNAi and EMSA experiments, and in silico predictions, we propose that the described SNVs might have acted on FOXF1 enhancer as hypermorphs.

Simple Summary Melanotic neuroectodermal tumor of infancy (MNTI) is a rare tumor of uncertain origin, morphologically overlapping other rare neoplasms such as pineal anlage tumor (PAT) and a subset of medulloblastomas (i.e., melanotic medulloblastoma). Despite the similarities with MNTI, their possible histogenetic relationship has been traditionally disregarded based on their aggressive behavior and dismal prognosis. The aim of this study was to further characterize the molecular features of MNTI and PAT based on DNA-methylation and copy number variation profiling analysis. We found that MNTI shares a methylation profile with group 3 high-risk medulloblastoma, and potentially with PAT, suggesting a common histogenesis. Most MNTIs in our series lacked copy number variation alterations, whereas their presence in the one PAT deserves further study in larger cohorts to better determine their impact in prognosis and biologic behavior. Abstract MNTI is a rare tumor of indeterminate histogenesis and molecular signature. We performed methylation and copy number variation (CNV) profiles in patients with MNTI (n = 7) and PAT (n = 1) compared to the methylation brain tumor classifier v11b4 (BT-C) and the medulloblastoma (MB) classifier group 3/4 v1.0 (MB3/4-C). The patients’ mean age was 8 months (range: 4–48). The BT-C classified five MNTIs and one PAT (relapse) as class family MB-G3/G4, subclass group 3 (score: >0.9). The remaining two MNTIs and PAT (primary) were classified as class family plexus tumor, subclass pediatric (scores: >0.45). The MB3/4-C classified all MNTIs as high-risk MB-G3, Subtype II (score: >0.45). The primary PAT was classified as subtype III (score: 0.99) and its relapse as subtype II/III. MNTI and PAT clustered close to MB-G3. CNV analysis showed multiple rearrangements in one PAT and two MNTIs. The median follow-up was 54 months (four MNTIs in remission, one PAT died). In conclusion, we demonstrated that MNTI shares a homogenous methylation profile with MB-G3, and possibly with PAT. The role of a multipotent progenitor cell (i.e., early cranial neural crest cell) in their histogenesis and the influence of the anatomical site, tumor microenvironment, and other cytogenetic events in their divergent biologic behavior deserve further investigation.

The Fontan operation is a widely used palliative procedure in patients with single-ventricle anatomy that results in liver injury. As timely identification of liver fibrosis may result in management changes to Fontan patients, the aim of our study was to identify clinically meaningful semi quantitative/quantitative pathologic parameters for biopsy assessment. We performed a retrospective review of 74 liver needle biopsies from Fontan patients. Fibrosis was assessed using quantitative % collagen deposition by Sirius red image analysis, METAVIR, congestive hepatic fibrosis score, sinusoidal fibrosis score, and sinusoidal dilation score. Contemporaneous laboratory, hemodynamic, and ultrasound data were collected. Centrilobular and peri sinusoidal fibrosis was observed in all cases, with 39.2% high grade. Portal fibrosis was observed in 93.2%, with 36.2% high-grade (METAVIR F3-F4). Cirrhosis was observed in 5.4%. % Collagen deposition was increased over control tissue (P < .001) and correlated with time from Fontan (r = 0.3, P = .009) and prothrombin time (r = 0.25, P = .034). Mildly elevated prothrombin time/international normalized ratio was the only measure of liver function consistently associated with multiple high-grade fibrosis scores (METAVIR P = .046, sinusoidal fibrosis P = .018). Abnormal liver echotexture on ultrasound was associated with high-grade congestive hepatic fibrosis score (P = .03). Pathologic gradings and %CD correlated with each other (r = 0.48-0.8, P < .001). Hepatic fibrosis in Fontan patients in our study is universally present, appears to be time dependent, and correlates with few laboratory measurements of liver function. Careful assessment of needle liver biopsies lends a more meaningful measure of liver fibrosis in the Fontan patient than clinical and laboratory data, allowing for appropriate changes to patient management.

Genomic alterations are important biological markers for cancer diagnosis and prognosis, disease classification, risk stratification, and treatment selection. Chromosomal microarray analysis (CMA) and next-generation sequencing (NGS) technologies are superb new tools for evaluating cancer genomes. These state-of-the-art technologies offer high-throughput, highly accurate, targeted and whole-genome evaluation of genomic alterations in tumor tissues. The application of CMA and NGS technologies in cancer research has generated a wealth of useful information about the landscape of genomic alterations in cancer and their implications in cancer care. As the knowledge base in cancer genomics and genome biology grows, the focus of research is now shifting toward the clinical applications of these technologies to improve patient care. Although not yet standard of care in cancer, there is an increasing interest among the cancer genomics communities in applying these new technologies to cancer diagnosis in the Clinical Laboratory Improvement Amendments (CLIA)-certified laboratories. Many clinical laboratories have already started adopting these technologies for cancer genomic analysis. We anticipate that CMA and NGS will soon become the major diagnostic means for cancer genomic analysis to meet the increasing demands of precision cancer care.

Introduction: Pediatric histiocytic neoplasms are clonal hematopoietic disorders driven by mutations activating the mitogen-activated protein kinase (MAPK) pathway, such as BRAF- V600E. In non-BRAFV600E cases, we investigated alternative MAPK mutations and found two novel BRAF gene fusions. We have previously shown effective targeting of BRAF fusions (KIAA1549-BRAF) in pediatric low-grade gliomas (PLGGs) with paradox breaker RAF inhibitor (RAFi), PLX8394 and MEK inhibitors (MEKi). Here, we investigate the distinct responsiveness of novel BRAF fusions to RAFi therapies and explore the mechanistic basis of such differential responses compared to other BRAF fusions. Method: Two histiocytic patient tumors were analyzed using the CHOP Comprehensive Next- Gen Sequencing Solid Tumor Panel and a targeted RNA-seq panel for 106 fusion partner genes. Novel BRAF fusions identified were sub-cloned to create heterologous cell models. Immunoblotting of serum starved cells measured MAPK and PI3K pathway activation and soft agar assay tested for oncogenic phenotypes driven by BRAF fusions, along with response to PLX8394, LY3009120 (pan-RAF dimer inhibitor), and MEKi. Co-immunoprecipitation assays using Myc- and Flag-tagged BRAF fusion constructs assessed dimerization profiles, with or without inhibitors. Result: In the two M- and L-type histiocytic neoplasms assessed, we found novel and rare BRAF gene fusions, MTAP-BRAF and MS4A6A-BRAF, respectively. Both BRAF fusions activated the MAPK/ PI3K pathways and showed homo- and hetero-dimerization with BRAF and the respective N-terminal fusion partner. Compared to common BRAF fusions, MTAP-BRAF and MS4A6A- BRAF did not respond to PLX8394 due to no disruption of active fusion homo- and hetero-dimers, which was in turn was due to the untargeted, stable dimerization mediated by the N-terminal fusion partners. Conversely, we observed robust suppression with LY3009120 that bound fusion dimers and kept them in an inactivate confirmation. MEKi selumetinib and trametinib also suppressed fusion driven signaling and oncogenic phenotypes. Conclusion: We show that novel MTAP-BRAF and MS4A6A-BRAF fusions, found in histiocytic tumors, do not respond to RAFi PLX8394 but are targeted by LY3009120 or MEKi. Our finding that PLX8394 does not disrupt MTAP-BRAF or MS4A6A-BRAF dimerization due to contribution of N-terminal partners defines a novel paradigm for the distinct mechanisms sought by BRAF fusions in response to RAFi therapy. We show potent suppression of these mechanistically distinct BRAF fusions with MEKi or LY3009120 which function independent of vulnerability to fusion dimerization. Overall, this study highlights the unique and differential biology hijacked by BRAF fusions in response to RAFi and further warrants detailed mechanistic classification of BRAF fusions based on their responsiveness to targeted agents. Citation Format: Payal Jain, Lea F. Surrey, Joshua Straka, Pierre Russo, Richard Womer, Marilyn Li, Phillip B. Storm, Angela J. Waanders, Michael Hogarty, Jennifer Picarsic, Adam C. Resnick. Novel BRAF gene fusions in pediatric histiocytic neoplasms respond differentially to RAF targeted therapies based on dimerization profiles [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 632.

Introduction: In children, approximately 7% of the non-CNS solid tumors include extremely rare histologies such as angiosarcomas and histiocytic neoplasms. While most recurrent histologies can be identified with a commonly occurring alteration or associated with a known biologic mechanism, rare solid tumors remain poorly characterized given their low frequency of occurrence and intrapatient tumor heterogeneity. Our group and others have demonstrated gene fusions (GFs) as unique oncogenic alterations in pediatric gliomas to guide prognosis, diagnosis, and therapeutic interventions. Here, we investigated the role of unique GFs as individualized therapeutic targets in 3 patients with rare non-CNS malignancies and explored GF-directed precision medicine approaches. Methods: We selected a patient with the rare diagnosis of pediatric angiosarcoma (pAS) and two with pediatric histiocytic neoplasms spanning the juvenille xanthogranuloma (JXG) family and malignant histiocytoses groups. Neoplasms were analyzed using the CHOP Comprehensive Next-Generation Sequencing Solid Tumor Panel as well as a targeted RNA-seq panel for 106 fusion partner genes. For novel gene fusions identified, we performed molecular and therapeutic characterization, including subcloning to create heterologous cell models. Cellular assays were used to assess oncogenic transformation, test mechanistic activation of related downstream signaling pathways via cellular assays, and examine targeting of GFs with specific small-molecule inhibitors. Results and Discussion: We identified a novel NOTCH1-ROS1 gene fusion in pAs, and rare BRAF-fusions, MTAP-BRAF and MS4A6A-BRAF, in malignant and JXG family histiocytic neoplasms, respectively. We also identified a germline TP53 p.T123Wfs*12 pathogenic variant, and the cancer predisposition team confirmed Li Fraumeni syndrome in the angiosarcoma patient. Our studies demonstrate that the NOTCH1-ROS1 fusion and both BRAF-fusions are potent oncogenes capable of inducing neoplastic transformation in cells and tumor formation in a murine allograft model. The kinase domains of ROS1 and BRAF are retained and activate the MAPK/PI3K/mTOR and JAK-STAT pathways in respective GF- expressing models, driven by potent dimerization of the GFs. Upon testing ROS1-targeted tyrosine kinase inhibitors (TKI) against NOTCH1-ROS1, we observe dose-dependent suppression of Notch1-Ros1 driven cellular activity and concurrent inhibition of tumor growth as well as prolonged survival after oral monotherapy. Interestingly, BRAF-fusions do not respond to second-generation BRAF inhibitors but can be suppressed by RAF dimer-inhibitor LY3009120 and MEK inhibitors. Overall, these data suggest that ongoing genomic profiling of rare pediatric tumors may reveal actionable drivers, and molecular testing of putative oncogenic fusions is imperative for improvement of patient outcomes through precision therapy. Citation Format: Payal Jain, Lea F. Surrey, Joshua Straka, Tiffany Smith, Sudarshan Iyer, Elizabeth Fox, Monika Davare, Jennifer Picarsic, Marilyn Li, Angela J. Waanders, Adam C. Resnick. Unique gene fusions inform targeted therapeutic strategies across extremely rare, non-CNS pediatric solid tumors [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr A37.

e13666 Background: Molecular profiling using NGS technology is critical for tumor diagnosis, risk stratification, and treatment selection. There are limited data in childhood cancers regarding evolution of genomic changes under the selective pressure of chemoradiotherapy. Here we report on serial testing of hematologic and solid pediatric tumor specimens across the spectrum of diagnosis, during treatment and disease relapse. Methods: Since 2016, 2,144 somatic NGS assays from 1,727 unique cancer patients were performed using the Comprehensive Hematological Malignancy Panel (CHMP) or the Comprehensive Solid Tumor Panel (CSTP). Serial tumor analysis was performed on 155 patients. All tumors were profiled for SNVs/indels, copy number alterations (CNAs), and fusions. The clinical impact on diagnosis, prognosis, and therapy was assessed. Results: 85 and 70 patients were tested with CHMP and CSTP, respectively. 86.5% (134/155) of patients underwent 1 subsequent genetic testing, while 13.5% (21/155) were serially tested for 3 - 6 times. Relapsed or therapy-refractory tumor was the most common indication for repeat CHMP and CSTP analysis of tumor genomics (64.5%, 100/155), primarily to survey for new targetable cancer driver mutations. The second most common reason for serial testing with CHMP was to monitor clonal evolution for patients with bone marrow failure syndromes and/or myelodysplastic syndromes, which resulted in a new cancer diagnosis in 14.6% (6/41) patients. For CSTP, the second most common reason for serial testing was to test a different part of the same tumor for tumors with histologic and/or radiographic heterogeneity (27.1%, 19/70). Of all patients with serial testing, 70 had at least one clinically significant new SNV/indel, 44 had distinct CNAs, and 4 had new clinically actionable fusions. Overall, clinically significant new results were detected in 81 (52.3%) patients, including 53 patients with new clonal changes indicating disease evolution, 31 of diagnostic significance, 9 of prognostic significance, and 8 suggesting new treatment options. Conclusions: Taken together, these data highlight the clinical importance of serial testing of pediatric tumors for potential biomarkers that may impact patients’ care at various time points across the spectrum of their diseases.

Mutations in SETD2 are found in many tumors, including central nervous system (CNS) tumors. Previous work has shown these mutations occur specifically in high grade gliomas of the cerebral hemispheres in pediatric and young adult patients. We investigated SETD2 mutations in a cohort of approximately 640 CNS tumors via next generation sequencing; 23 mutations were detected across 19 primary CNS tumors. Mutations were found in a wide variety of tumors and locations at a broad range of allele frequencies. SETD2 mutations were seen in both low and high grade gliomas as well as non-glial tumors, and occurred in patients greater than 55 years of age, in addition to pediatric and young adult patients. High grade gliomas at first occurrence demonstrated either frameshift/truncating mutations or point mutations at high allele frequencies, whereas recurrent high grade gliomas frequently harbored subclones with point mutations in SETD2 at lower allele frequencies in the setting of higher mutational burdens. Comparison with the TCGA dataset demonstrated consistent findings. Finally, immunohistochemistry showed decreased staining for H3K36me3 in our cohort of SETD2 mutant tumors compared to wildtype controls. Our data further describe the spectrum of tumors in which SETD2 mutations are found and provide a context for interpretation of these mutations in the clinical setting.

Beckwith-Wiedemann syndrome (BWS) is a genetic syndrome associated with overgrowth and cancer predisposition, including predisposition to Wilms tumor (WT). Patients with BWS and BWS spectrum (BWSp) are screened from birth to age 7 years for BWS-associated cancers. However, in some cases a BWS-associated cancer may be the first recognized manifestation of the syndrome. We describe 12 patients diagnosed with BWS after presenting with a WT. We discuss the features of BWS in these patients and hypothesize that earlier detection of BWS by attention to its subtler manifestations could lead to earlier detection of children at risk for associated malignancies.

ContextAdults with differentiated thyroid cancer (DTC) and Graves disease (GD) demonstrate a greater reported disease burden and aggressive DTC behavior. To date, no studies have examined the impact and long-term outcome of concurrent GD and DTC (GD-DTC) in children and young adults.DesignSingle institution, retrospective longitudinal cohort study between 1997 and 2016.ParticipantsOne hundred thirty-nine children and young adults with DTC, diagnosed at median age 15 (range, 5 to 23) years, compared with 12 patients with GD-DTC, median age 18 (range, 12 to 20) years.Major Outcome MeasuresPatient demographics, preoperative imaging, fine needle aspiration (FNA) cytology, operative and pathological reports, laboratory studies, treatment, and subsequent 2-year outcomes.ResultsCompared with DTC, patients with GD-DTC were significantly older at the time of DTC diagnosis (P < 0.01). Patients with GD-DTC were more likely to exhibit microcarcinoma (P < 0.01), and 2 of 12 (17%) demonstrated tall cell variant papillary thyroid cancer (PTC) vs 2 of 139 (2%) in patients who had DTC alone (P = 0.03). Although patients with DTC showed greater lymphovascular invasion (60% vs 25%; P = 0.03), no group differences were noted in extrathyroidal extension, regional lymph node, and distant or lung metastasis. There were no group differences in the 2-year outcome for remission, persistent disease, or recurrence.ConclusionsConcurrent DTC in pediatric patients with GD is not associated with a greater disease burden at presentation and shows no significant difference in 2-year outcomes compared with DTC alone. Similar to adults, microcarcinoma and tall cell variant PTC is prevalent in pediatric patients with GD-DTC. For patients who have GD-DTC with an identified nodule on ultrasound imaging prior to definitive therapy, FNA biopsy is recommended to guide definitive treatment.

The staged Fontan procedure has shown promising short-term outcomes in patients with single ventricles. However, Fontan-associated liver disease is a marked problem as patients age. The purpose of this study is to investigate the relationship between hemodynamics and liver fibrosis in patients undergoing the Fontan.A total of 33 patients undergoing the Fontan with liver fibrosis were included in this study. Cardiac magnetic resonance and phase-contrast cardiac magnetic resonance data, as well as catheterization measurements and liver biopsies, were obtained for each patient. Computational fluid dynamic simulations were performed to quantify total cavopulmonary connection hemodynamics using patient-specific anatomies and blood flow waveforms reconstructed from cardiac magnetic resonance data. Collagen deposition (as a measure of liver fibrosis) was quantified by digital image analysis of Sirius Red stained slides. Statistical analyses were performed to investigate potential relationships between liver fibrosis and Fontan hemodynamics.Liver fibrosis was found to be related to global metrics (inferior vena cava flow, ventricle power output) rather than to local total cavopulmonary connection hemodynamics and efficiency. Indexed inferior vena cava flow showed a significant, positive correlation with liver fibrosis (rho = 0.624, P .001). Upper and lower Sirius Red tertile comparisons showed a significant difference in indexed inferior vena cava flow (P = .008).Significant increases in inferior vena cava flow consistent with fibrosis induced arterialization and ventricular power output suggest a burden being placed on the single ventricle from liver fibrosis. Local total cavopulmonary connection flow dynamics do not seem to influence the degree of fibrosis. Favorable total cavopulmonary connection hemodynamics may not be enough to overcome the power shortage and elevated venous pressures inherent to a Fontan circulation.

Background Congestive hepatopathy is a recognized complication of Fontan physiology. Data regarding the incidence of hepatopathy and risk factors are lacking. Methods and Results Liver biopsies and cardiac catherizations were performed as part of an evaluation offered to all patients ≥10 years after Fontan. Quantitative determination of hepatic fibrosis was performed using Sirius red staining with automated calculation of collagen deposition per slide (% CD ). Biopsies from included subjects were compared to stained specimens from controls without known fibrotic liver disease. Patient characteristics, echocardiographic findings, and hemodynamic measures were evaluated as potential risk factors. The cohort consisted of 67 patients (31 female) at mean age of 17.3±4.5 years and mean time from Fontan of 14.9±4.5 years. Right ventricular morphology was present in 37 subjects. Median % CD by Sirius red staining was 21.6% (range 8.7% to 49.4%) compared to 2.6% (range 2.2% to 3.0%) in controls. There was a significant correlation between time from Fontan and degree of Sirius red staining ( r =0.33, P CD . The median inferior vena cava pressure was 13 mm Hg (range 6‐24 mm Hg) and did not correlate with % CD . There was no difference in % CD based on ventricular morphology or severity of atrioventricular valve insufficiency. Conclusions In this cohort of predominantly asymptomatic children and adolescents electively evaluated after a Fontan operation, all exhibited evidence for hepatic fibrosis as measured by collagen deposition in the liver. Time from Fontan was the only factor significantly associated with collagen deposition. These findings demonstrate that liver fibrosis is an inherent feature of Fontan physiology and that the degree of fibrosis increases over time.

Molecular characterization of pediatric low-grade gliomas (pLGG) have identified recurrent alterations, most commonly involving BRAF and NF1, which have been exploited to aid in diagnosis and treatment decisions. However, a significant portion do not have these canonical alterations, and the genetics and clinical course of these tumors remains unknown. We molecularly characterized a cohort of 986 patients diagnosed at SickKids from 1990–2017 with comprehensive long-term clinical data. For the rare non-canonical alterations uncovered, data was supplemented with cases from the Taskforce. Within the SickKids cohort, 72% were driven by canonical alterations in either BRAF (38% fusions, 16% V600E) or NF1 (18%). 11.5% were driven via recurrent non-canonical events involving FGFR1 (6%), FGFR2 (1%), MYB (1%), MYBL1 (1%), H3F3A (2%) or IDH1 (0.5%). The Taskforce supplemented cohort revealed that most FGFR1/2 fusions (n=51) were hemispheric and benign, with no deaths observed. In contrast, FGFR1 activating mutations (n=29) were commonly observed as a second hit, occurred throughout the neuraxis, and at an older age. These tumors were more aggressive, having a poor response to therapy and resulting in death. MYB/MYBL1 alterations (n=19) were seen exclusively in angiocentric gliomas and diffuse astrocytomas, respectively. Both are primarily hemispheric and often occur as massive lesions in childhood, yet have excellent long-term outcome. IDH1 (n=8) was seen mostly in adolescents (15–18 years). Importantly, several had a long history of seizures and presented with small lesions years prior to surgery. While all tumours eventually progressed, some (n=6) are alive up to 13 years post diagnosis. H3F3A driven pLGGs (n=12) progressed early, (median 11 months) and all patients succumbed to their disease. The work here represents the largest cohort of non-canonical pLGGs assembled. Our work supports a diagnostic workflow which includes these alterations, and we provide preliminary clinical features of these tumors to better equip practicing clinicians.

Liver fibrosis is a serious complication in Fontan survivors and potential solutions to stop or delay progression are needed. The purpose of this study is to investigate if prior hemodynamics are predictive of future liver fibrosis in Fontan patients. 21 Fontan patients who underwent cardiac

NLRC4-inflammasome hyperactivity causes infantile-onset Macrophage Activation Syndrome and enterocolitis with extraordinary serum IL-18 elevation (NLRC4-MAS). Herein, we report a critically ill infant with severe, refractory NLRC4-MAS who showed sustained response to treatment with experimental IL-18 inhibition.

Introduction: Congestive hepatopathy is increasingly recognized as a complication of Fontan physiology. Prospective data regarding the incidence of hepatopathy and risk factors for its development are lacking. Methods: Liver biopsies were obtained as part of a routine program of comprehensive end-organ evaluation offered to all patients >10 years after Fontan operation (FO) through the Single Ventricle Survivorship Program. Evaluation included cardiac catheterization and contemporaneous percutaneous liver biopsy. Quantitative determination of hepatic fibrosis was performed using Sirius red staining for collagen with automated calculation of percent positive staining per slide. Patient specific characteristics, echocardiographic findings, and hemodynamic measures were assessed and evaluated as potential risk factors for collagen deposition using Pearson correlation. Differences in collagen deposition (%CD) between subgroups were assessed using the student t-test. Results: The cohort consisted of 67 patients (36 male) at mean age of 17.3 ±4.5 years and mean time from Fontan of 14.9 ±4.5 years. Right ventricular morphology was present in 37 subjects; 30 with hypoplastic left heart syndrome. Mean %CD by Sirius red staining was 23.8 ±9.5% (range 8.7-49.4%) as compared to 2.6 ±0.3% in controls. There was significant correlation between time from Fontan and degree of Sirius red staining (r=0.33, p=0.006). Serum liver enzymes and platelet count did not correlate with %CD. The median inferior vena cava (IVC) pressure was 13 mmHg (range 6-24 mmHg) and did not correlate with %CD. There was no difference in %CD between those with a measured IVC pressure ≥13 mmHg versus those with a pressure Conclusion: In this cohort of predominantly asymptomatic children and adolescents electively evaluated after FO, all exhibited evidence for hepatic fibrosis as measured by collagen deposition in the liver. Time from FO was the only factor in this cohort that was significantly associated with collagen. These findings demonstrate that liver fibrosis is an inherent feature of Fontan physiology and that the degree of fibrosis increases over time.

Hypoplastic left heart syndrome (HLHS) is the third most common cause of critical congenital heart disease in newborns, and one of the most challenging forms to treat. Secondary pulmonary lymphangiectasia has been recognized in association with HLHS, an appearance described on fetal MRI as the “nutmeg lung.” To investigate the association of fetal nutmeg lung with HLHS survival. A retrospective search of the fetal MRI database was performed. The nutmeg lung pattern was defined as T2 heterogeneous signal with tubular structures radiating peripherally from the hila. Postnatal echocardiograms and charts were reviewed. Forty-four fetal MR studies met inclusion criteria, of which 4 patients (9%) had the nutmeg lung pattern and 3 of whom also had restrictive lesions. Mortality in this nutmeg lung group was 100% by 5 months of age. Of the 40 patients without nutmeg lung, mortality/orthotopic heart transplant (OHT) was 35%. Of these 40 patients without nutmeg lung, 5 had restriction on echo, 3 of whom died/had OHT before 5 months of age (60% of patients with restriction and non-nutmeg lung). There was a significantly higher incidence of restrictive lesions (P = 0.02) and mortality/OHT (P = 0.02) in patients with nutmeg lung compared to those without. The nutmeg lung MR appearance in HLHS fetuses is associated with increased mortality/OHT (100% in the first 5 months of life compared to 35% with HLHS alone). Not all patients with restrictive lesions develop nutmeg lung, and outcome is not as poor when restriction is present in isolation. Dedicated evaluation for nutmeg lung pattern on fetal MR studies may be useful to guide prognostication and aid clinicians in counseling parents of fetuses with HLHS.

Severe Eosinophilic Gastroenteritis in a Crohn’s Disease Patient Treated With Infliximab and Adalimumab

Thyroid transcription factor-1 (TTF-1) and Napsin-A (NapA) are frequently used to classify a tumor of unknown origin as lung or thyroid primary. Although recent studies have shown that nuclear TTF-1 positivity occasionally occurs in adenocarcinoma of nonpulmonary or thyroid origin dependent upon the antibody clone, TTF-1 has been reported as negative or infrequently positive in tumors of biliary origin. On the basis of an index case of cholangiocarcinoma expressing TTF-1, we were prompted to study TTF-1 and NapA positivity in cholangiocarcinoma. Archived paraffin-embedded tissue blocks from liver, gallbladder, and pancreato-biliary resections were chosen for cholangiocarcinoma (n=33) and non-neoplastic intrahepatic and extrahepatic biliary epithelium control tissue (n=26). Immunohistochemical analysis for TTF-1 and NapA was performed and graded for intensity and quantity. TTF-1 was negative in control biliary tissue but positive in 27.2% of cholangiocarcinomas. All TTF-1-positive cases (n=9) were extrahepatic (P=0.01), and most arose from the upper biliary tract (gallbladder and hepatic ducts). TTF-1 positivity was associated with age 60 years and above (P=0.01) but not with sex. Three TTF-1-positive cases were also NapA positive. NapA staining showed apical granular staining of the adjacent non-neoplastic epithelium in 6 cases (18.1%). In summary, 47.4% of extrahepatic cholangiocarcinoma expressed TTF-1, 33.3% of which coexpressed NapA. Cholangiocarcinoma should be considered in the differential when evaluating a TTF-1-positive tumor of unknown primary. As TTF-1 and NapA are not known for biliary system development or detected in non-neoplastic biliary epithelium, the significance of this "pulmonary" phenotype in a subset of extrahepatic cholangiocarcinoma is unknown and needs further investigation.

A 14-year-old boy with obesity was referred to our center for evaluation of elevated blood pressures. His past medical history was notable for prematurity. Gestational age was 31.5 weeks, and neonatal issues included respiratory distress, hyperbilirubinemia, and grade I intraventricular hemorrhage. He did not have umbilical lines. He also had a history of tonsillectomy, adenoidectomy, and myringotomy tubes. His family history was relevant for his mother having longstanding hypertension and proteinuria, and his maternal grandmother died in her sixth decade of life secondary to cardiac amyloidosis and multiple myeloma. She presented with end-stage kidney disease (ESKD) a few years earlier and did not have a kidney biopsy. Physical examination was unremarkable except for a blood pressure of 154/103 and obesity. On random urinalysis, he had 2+ proteinuria and no microhematuria. His laboratory studies showed normal kidney function with serum creatinine of 0.6 mg/dl, normal electrolytes, mild hypoalbuminemia (albumin 3.5 g/dl) and anemia (hemoglobin 11.3 g/dl), Fig. 1 Kidney biopsy findings. a Light microscopy shows striking glomerulomegaly and lobularity of glomerular tufts, marked mesangial hypercellularity, and markedly increased mesangial matrix [hematoxylin and eosin (H&E) stain, 200×]. b Periodic acid-Schiff (PAS) stain shows increased amounts of PAS-positive material in the capillary loops with irregular thickening (400×). c, d Scattered tubular atrophy, moderate patchy interstitial fibrosis, mild patchy interstitial inflammation, and globally sclerotic glomeruli seen on H&E and trichrome stains, respectively (200×). e Electron microscopy (EM) shows extensive mesangial and subendothelial lightly electron-dense, granular deposits and partial effacement of foot processes. f Fibrillary appearance of deposits (small randomly oriented fibrils) on higher magnification. Note: Immunofluorescence was negative for IgA, IgG, IgM, C3, and C1q, immunohistochemistry was negative for kappa and lambda light chains, and Congo Red staining was negative The answers to these questions can be found at http://dx.doi.org/10.1007/ s00467-015-3128-0.

Germ line mutations in genes that encode proteins involved in the DNA damage response predispose patients to a variety of tumors. Checkpoint kinase 2, encoded by the CHEK2 gene, is important in transducing the DNA damage response. Germ line CHEK2 mutations are seen in a subset of patients with a familial breast cancer and sarcoma phenotype. We report a case of retroperitoneal dedifferentiated liposarcoma in a 61-year-old female with germ line CHEK2 mutation. MDM2 gene amplification normally present and used to aid in the diagnosis of retroperitoneal dedifferentiated liposarcoma was absent in this case. Lack of MDM2 overexpression has similarly been reported in liposarcomas arising in patients with germ line TP53 mutations. We propose this case may highlight a nonamplified MDM2 phenotype in well- and dedifferentiated liposarcomas arising in patients with germ line mutations of genes involved in p53-associated DNA damage response pathways.

Persistence of human papillomavirus (HPV) and cervical disease in the context of HIV co-infection can be influenced by introduction of antiretroviral therapy (ART) and sustained immune activation despite ART. We conducted a cross-sectional study in order to evaluate immune activation/exhaustion in ART-suppressed HIV(+) women with or without high-risk (HR) HPV-related cervical intraepithelial neoplasia (CIN). 55 South African women were recruited in three groups: HR (-) (n = 16) and HR (+) (n = 15) HPV with negative cervical histopathology, and HR (+) HPV with CIN grade 1/2/3 (n = 24). Sampling included endocervical brushing (HPV DNA genotyping), Pap smear (cytology), colposcopic punch biopsy (histopathology, histochemical evaluation of immune cells), and peripheral blood (clinical assessment, flow cytometry-based immune subset characterization). Statistics were done using R2.5.1. Irrespective of the presence of CIN, HR (+) HPV women had higher circulating levels of T cells expressing markers of activation/exhaustion (CD38, PD1, CTLA-4, BTLA, CD160), Tregs, and myeloid subsets expressing corresponding ligands (PDL1, PDL2, CD86, CD40, HVEM) than HR (-) HPV women. A decrease in circulating NK cells was associated with CIN grade. CD4(+) T cell count associated negatively with T cell exhaustion and expression of negative regulators on myeloid cells. Women with CIN when compared to HR (-) HPV women, had higher cervical cell density in stroma and epithelium for CD4(+), CD68(+), and CD11c(+) cells, and only in stroma for CD8(+) cells. We conclude that in ART-suppressed HIV-infected women with HPV co-infection the levels of T and myeloid cell activation/exhaustion are associated with the presence of HR HPV genotypes.

Functioning adrenal adenomas are well-described entities that can rarely occur outside the adrenal gland in the ectopic adrenal tissue. Similarly, myelolipoma is an another benign lesion of the adrenal tissue which can rarely occur outside the adrenal gland. We report the first case of a testosterone producing an extra-adrenal adrenocortical oncocytoma accompanied by a myelolipoma. The patient presented with virilization and elevated androgen levels. Imaging revealed a retroperitoneal mass, which histologically consisted of oncocytes and intermingled myelolipoma. Postoperative androgen levels decreased to normal. The tumor cells were strongly positive for inhibin and Melan-A, supporting the adrenal origin. This case demonstrates a diagnostic challenge in which correlation with histology, immunohistochemistry, and serum endocrine studies led to the final diagnosis.

Friedreich ataxia (FRDA) is an autosomal recessive neuro- and cardiodegenerative disorder for which there are no proven effective treatments. FRDA is caused by decreased expression and/or function of the protein frataxin. Frataxin chaperones iron in the mitochondrial matrix for the assembly of iron-sulfur clusters (ISCs), which are prosthetic groups critical for the function of the Krebs cycle and the mitochondrial electron transport chain (ETC). Decreased expression of frataxin or the yeast frataxin orthologue, Yfh1p, is associated with decreased ISC assembly, mitochondrial iron accumulation, and increased oxidative stress, all of which contribute to mitochondrial dysfunction. Using yeast depleted of Yfh1p, a high-throughput screening (HTS) assay was developed in which mitochondrial function was monitored by reduction of the tetrazolium dye WST-1 in a growth medium with a respiration-only carbon source. Of 101 200 compounds screened, 302 were identified that effectively rescue mitochondrial function. To confirm activities in mammalian cells and begin understanding mechanisms of action, secondary screening assays were developed using murine C2C12 cells and yeast mutants lacking specific complexes of the ETC, respectively. The compounds identified in this study have potential relevance for other neurodegenerative disorders associated with mitochondrial dysfunction, such as Parkinson disease.