Lastly, patients with IMD and low serum NfL levels based on median NfL were found to have longer overall survival (OS) than patients with IMD and high serum NfL (HR 2.10, p = 0.01), though again, this association may be biased by neurotoxic therapies used in advanced systemic metastatic disease [19,22]. The gene discussed is NEFL; the disease is metastatic neoplasm.