MBRS-73. AN EXPLORATORY ANALYSIS LOOKING AT THE ASSOCIATION OF GERMLINE CODING MUTATIONS WITH IMPAIRED DEVELOPMENT AND ADAPTIVE BEHAVIOR FUNCTION IN PEDIATRIC MEDULLOBLASTOMA PATIENTS TREATED ON HEAD START 4

Children with brain tumors often carry germline mutations known to contribute to tumorigenesis and treatment response; however, little is known about how these mutations impact developmental and behavioral outcomes. As the molecular mechanisms governing cancerous and normal tissues expand, we hypothesize that specific germline variants may impact baseline neurocognitive function and/or treatment-induced toxicities. In this pilot study, ten children on the Head Start 4 (HS4) clinical 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 twenty genes with alterations associated with lower scores with p-values less than 0.05. 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 respectively 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 hypothesize that additional analyses of HS4 patients will reveal alterations in cell-to-cell communication and signal transduction pathways, common molecular perturbations in tumors that would likely impact central nervous system function. Validation studies are essential to improve our understanding of the functional impact of germline variants on both tumor and regular tissue biology, allowing for novel strategies to circumvent these delays.