NF1 and malignant peripheral nerve sheath tumor: Consequently, the mutational frequency in common regions was 1.79 and 0.89 mutations per megabase for MPNST-NF1-001 and MPNST-NF1-002, respectively, and 18.38 and 15.33 mutations per megabase for MPNST-SP-001 and MPNST-SP-002, respectively.