About half of MPNSTs occur in people with neurofibromatosis type 1 (NF1), an autosomal dominant tumor predisposition syndrome with an incidence of 1 in 2500–3000 births worldwide.2 Retrospective studies of MPNSTs in people with NF1 reported a 5-year disease-free survival rate of 34%–60%, which is somewhat worse than sporadic MPNST (in people without NF1).3 NF1 results from germline heterozygosity for an NF1 gene pathogenic variant resulting in reduced activity of the gene’s encoded protein neurofibromin, a RAS GTPase tumor suppressor. The gene discussed is NF1; the disease is malignant peripheral nerve sheath tumor.