SLC24A1 and myeloid sarcoma: The mean age at MS onset for SLC24A1 p.Leu26Phe carriers is 31.8 years (SD ± 10.0), with a clinical course consistent with RRMS (II-9, III-2, 3, 4), PPMS (II-2, 4, III-1) or SPMS (II-14) (S1 Table).