BTK and acquired polycythemia vera: BTK inhibitors have been investigated in various autoimmune disorders, including autoimmune hemolytic anemia (AIHA), immune thrombocytopenia (ITP), multiple sclerosis (MS), atopic dermatitis (AD), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjögren’s disease (SD), multiple sclerosis (MS), and pemphigus vulgaris (PV).