NRAS and plasma cell myeloma: In this study, we used ddPCR to detect BRAF, KRAS and NRAS mutations (BRAF 600Mx, KRAS Mx, NRAS G12/G13, NRAS Q61) in 83 diagnosed MM patients in both the tumor DNA and for 17 of these patients, also in plasma cfDNA, which is the first study revealing the prevalence and clinicopathological significances of BRAF, KRAS and NRAS mutations in Chinese patients with myeloma using this ddPCR method.