Clinical and molecular characteristics of NF1 mutations identified on hereditary cancer multi-gene panels.

e13612Background: Somatic mutations to the NF1 gene have been shown to play a role in several tumor types. Evaluation of patients with Neurofibromatosis type 1 (NF1) has led to the longstanding clinical observation of a high rate of somatic mosaicism in NF1. We explored the clinical and genetic features of patients with NF1 mutations identified through cancer susceptibility testing. Methods: Results from a cohort of 118,768 patients who underwent multigene panel testing (MGPT) were queried to identify probands with a NF1 pathogenic/ likely pathogenic variant. Next generation sequencing was performed on panels of 2-67 hereditary cancer genes. Review of test requisition forms and available clinical history/pedigree was performed. NF1 cases were defined by concordance with NIH criteria. Additionally, we used a biphasic distribution to define a cutoff, dividing non-NF cases into normal and low variant allele frequency (VAF). Results: 158 total patients were identified; 89 patients had a reported clinical diag...