Moreover, when considering all ON patients (disregarding the prospective MS-ON or ION diagnosis), patients with CSF NF-L higher than the median (> 450 pg/ml) had more abundant CSF leukocytes than ON patients with NF-L < 450 pg/ml (10.5 cells/μl [3–42.2; n = 18] versus 2.0 [1–7.5; n = 17], p = 0.011, not shown). This evidence concerns the gene NEFL and myeloid sarcoma.