There was no washout period after beta-interferon and glatiramer acetate, but for patients on fingolimod, it was 1 month; on teriflunomide, 2 weeks, after undergoing the accelerated elimination procedure with cholestyramine; and on dimethyl fumarate, 1 week, except for one patient with lymphopenia that required a longer washout interval. The gene discussed is IFNB1; the disease is lymphopenia.