Higher NfL concentration in serum was significantly associated with the disease phenotype (p = 0.001, U = 424), with higher concentrations in RRMS-patients (median 12.32 pg/ml, IQR 12.71 pg/ml) than in CIS-patients (median 6.97 pg/ml, IQR 6.18 pg/ml). This evidence concerns the gene NEFL and in situ carcinoma.