3323 Juvenile Polyposis Syndrome Patients Without a Mutation in SMAD4 or BMPR1A: Clinical Presentation and Novel Drivers of Disease

OBJECTIVES/SPECIFIC AIMS: Juvenile Polyposis Syndrome (JPS) is an inherited cancer predisposition syndrome sometimes attributed to a germline mutation in SMAD4 or BMPR1A. However, many patients meet clinical criteria for JPS without having a pathogenic alteration in either gene. Herein, we perform a cross-sectional analysis of JPS patients at a pediatric and adult tertiary referral center to understand potential differences in the clinical presentation and outcomes of patients with or without a known causative gene mutation. Additionally, we conduct whole exome sequencing (WES) on a subset of the pediatric patients to evaluate for novel genomic drivers of disease. METHODS/STUDY POPULATION: Data were abstracted from medical charts using IRB-approved protocols at the Children’s Hospital of Philadelphia (CHOP) and the University of Pennsylvania (Penn). Records were reviewed for patients with a clinical diagnosis of JPS and genetic testing result and seen at either institution in the last 10 years (2008-2018). Patients recruited for sequencing were consented for blood draw through the CHOP IRB protocol, and had whole exome sequencing completed at 70X depth, with data analyzed through institutional pipeline. RESULTS/ANTICIPATED RESULTS: Records were reviewed for 41 patients at CHOP and 19 patients at Penn, for a total of 60 JPS patients. Mean age of CHOP cohort was 11 years: 58.5% male, mean length of follow up 3.9 years. Mean age Penn cohort was 33 years: 47.4% male, mean length of follow up 9.3 years. In the pediatric cohort, 7 patients (17%) had a mutation in BMPR1A (n=6) or SMAD4 (n=1); in the adult cohort, 15 patients (79%) had a mutation in BMPR1A (n=3) or SMAD4 (n=12). The average number of polyps in the pediatric cohort was not significantly higher in patients with a SMAD4 or BMPR1A mutation (9.3 polyps/year of surveillance with a SMAD4 or BMPR1A mutation, vs 5.7 polyps/year; p=0.19). In combined cohort review, all individuals that required gastrectomy and/or colectomy (n=8) as well as all those who developed gastrointestinal cancer (n=3) had a mutation in SMAD4 or BMPR1A. Of the patients who underwent whole exome sequencing (n=13), potential causative germline mutations were identified in four patients (30.8%); all potential drivers identified were within the TNF/BMP pathway. DISCUSSION/SIGNIFICANCE OF IMPACT: This data from a dual-institution review demonstrates that the rate of SMAD4/BMPR1A mutation in JPS is lower in a pediatric cohort compared to an adult cohort. Furthermore, although individuals with JPS may have similar clinical presentations in childhood regardless of whether or not a causative mutation is present, the presence of a mutation in SMAD4 or BMPR1A is associated with a more severe course of disease in adulthood. Further study and a larger cohort will be required to fully validate these findings. Approximately 30% of patients who underwent germline WES had a potential novel driver identified, with further validation underway.