NCOG-46. A PILOT STUDY OF GERMLINE CODING MUTATIONS ASSOCIATED WITH IMPAIRED DEVELOPMENT AND ADAPTIVE BEHAVIOR IN PEDIATRIC MEDULLOBLASTOMA PATIENTS TREATED ON HEAD START 4

Abstract Children with brain tumors often carry germline mutations that have long been known to contribute to tumorigenesis and treatment response. However, less is known about how germline mutations may impact developmental and behavioral outcomes for children with tumors of the central nervous system (CNS). As the molecular mechanisms governing cancerous and normal tissue expand, we hypothesize that particular germline variants may impact baseline neurocognitive function and/or treatment-induced toxicities. In this preliminary study, 10 children on the Head Start 4 trial diagnosed with medulloblastoma were assessed for baseline adaptive functioning using the Adaptive Behavior Assessment System Third Edition (ABAS-III) and germline whole-exome sequencing was performed. After filtering for high impact variants, Welch’s T-tests were used to identify mutations associated with lower ABAS-III General Adaptive Composite (GAC) scores, reflecting developmental and adaptive behavior delays compared with peers their age. We found 20 genes with alterations associated with lower scores with P-values less than 0.05, although none met FDR significance cutoffs. Genes found to be significant included LAMC1 (P=0.04) and KRTAP1-1 (P=0.045), which encode members of the laminin and keratin family and are involved in extracellular matrix adhesion. Mutations in PITX1, a known suppressor of RAS, were also associated with lower ABAS-III GAC scores (P=0.007). We suspect that follow-up studies with more patients will reveal alterations in cell-to-cell communication and signal transduction pathways, as these are common molecular perturbations in tumors that would likely impact regular CNS function. Future research with larger cohorts is essential to validate these findings and to improve our understanding of the functional impact of germline variants on both tumor and regular tissue biology, allowing for a more comprehensive view of the spectrum of neurodevelopmental impairment and novel strategies to circumvent these impairments. Funding: Thrasher Research Fund (JF, AC). R01CA108633, RC2CA148190, U10CA180850(NCI), and OSUCCC (AC).