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Background: The etiology of central nervous system (CNS) tumors in children is largely unknown and population-based studies of genetic predisposition are lacking., Methods: In this prospective, population-based study, we performed germline whole-genome sequencing in 128 children with CNS tumors, supplemented by a systematic pedigree analysis covering 3543 close relatives., Results: Thirteen children (10%) harbored pathogenic variants in known cancer genes. These children were more likely to have medulloblastoma (OR 5.9, CI 1.6-21.2) and develop metasynchronous CNS tumors (P = 0.01). Similar carrier frequencies were seen among children with low-grade glioma (12.8%) and high-grade tumors (12.2%). Next, considering the high mortality of childhood CNS tumors throughout most of human evolution, we explored known pediatric-onset cancer genes, showing that they are more evolutionarily constrained than genes associated with risk of adult-onset malignancies (P = 5e-4) and all other genes (P = 5e-17). Based on this observation, we expanded our analysis to 2986 genes exhibiting high evolutionary constraint in 141,456 humans. This analysis identified eight directly causative loss-of-functions variants, and showed a dose-response association between degree of constraint and likelihood of pathogenicity-raising the question of the role of other highly constrained gene alterations detected., Conclusions: Approximately 10% of pediatric CNS tumors can be attributed to rare variants in known cancer genes. Genes associated with high risk of childhood cancer show evolutionary evidence of constraint., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: Growth hormone deficiency (GHD) is the most common endocrine late effect in irradiated survivors of childhood brain tumors. This study aimed to determine the prevalence of GHD in adults treated with proton or photon irradiation for a brain tumor in childhood and to detect undiagnosed GHD., Design: This study is a cross-sectional study., Methods: We investigated GHD in 5-year survivors from two health regions in Denmark treated for childhood brain tumors with cranial or craniospinal irradiation in the period 1997-2015. Medical charts were reviewed for endocrinological and other health data. Survivors without a growth hormone (GH) test at final height were invited to a GH stimulation test., Results: Totally 41 (22 females) survivors with a median age of 21.7 years (range: 15.1-33.8 years) at follow-up and 14.8 years (range: 5.1-23.4 years) since diagnosis were included; 11 were treated with proton and 30 with photon irradiation; 18 of 21 survivors were previously found to have GHD; 16 of 20 survivors with no GH test at final height were tested, 8 (50 %) had GHD. In total, 26 of 41 patients (63%) had GHD. Insulin-like growth factor-1 (IGF-1) is associated poorly with the insulin tolerance test (ITT)., Conclusion: This study identified a high prevalence of undiagnosed GHD in survivors with no GH test at final height. The results stress the importance of screening for GHD at final height in survivors of childhood brain tumors with prior exposure to cranial irradiation, irrespective of radiation modality and IGF-1., Significance Statement: This cross-sectional study reports a prevalence of 63% of GHD in irradiated childhood brain tumor survivors. Furthermore, the study identified a considerable number of long-term survivors without a GH test at final height, of whom, 50% subsequently were shown to have undiagnosed GHD. Additionally, this study confirmed that a normal serum IGF-1 measurement cannot exclude the diagnosis of GHD in irradiated survivors. This illustrates the need for improvements in the diagnostic approach to GHD after reaching final height in childhood brain tumor survivors at risk of GHD. In summary, our study stresses the need for GHD testing in all adult survivors treated with cranial irradiation for a brain tumor in childhood irrespective of radiation modality.