This, in turn, indicates pronounced arterial constriction in the major retinal vessels, which is in line with data on upregulation of endothelin-1 in MS lesions and elevated serum and CSF levels of this vasoconstrictive peptide (Speciale et al., 2000; Haufschild et al., 2001; Halder and Milner, 2021). The gene discussed is EDN1; the disease is myeloid sarcoma.