Our results showed that sNfL levels were significantly elevated (at baseline) in the CIS cohort, and in a control RRMS group, compared to HC, in line with the findings of other studies corroborating that circulating NfL levels are associated with neuro‐axonal damage and are a marker for disease activity (Bittner et al., 2020; Disanto et al., 2017; Khalil et al., 2018; Kuhle et al., 2019). This evidence concerns the gene NEFL and in situ carcinoma.