Recent studies have revealed that NfL could be used as a biomarker to predict the MS disease activity, severity, prognosis, and also to monitor treatment response (Kuhle et al., 2015[59]; Disanto et al., 2016[23], 2017[24]; Varhaug et al., 2018[111]; Thebault et al., 2019[104]). The gene discussed is NEFL; the disease is myeloid sarcoma.