Neurofibromatosis and cancer. NF1 is one of he most frequent genetic cancer susceptibility syndromes. In this symposium we will review the clinical diagnosis and management of optic glioma in children with NF1, including a discussion of new drugs with activity in this challenging and unpredictable tumor. In addition, we will review new data comparing gene expression patterns in children with peripheral nerve tumors, with and without NF1. Finally we will review current understanding of the role of NF1 mutations in JMML and describe new approaches to diagnosis of JMML and measurement of minimal residual disease in JMML.