Compared to the 1st tertile with the lowest values of serum NfL at baseline, MS patients with higher serum NfL values in the 2nd and 3rd tertiles had a significantly higher hazard ratio (HR) of developing an EDSS ≥ 4 (2nd tertile: HR = 5.5 (95% CI 1.4–21.0), p = 0.012; 3rd tertile: HR = 5.2 (95% CI 1.5–18.6), p = 0.010), showing that they were on average > 5-times at higher risk of developing EDSS ≥ 4 over the follow-up (Fig. 6A). This evidence concerns the gene NEFL and myeloid sarcoma.