IFIH1 and viral infectious disease: Anti-SFPQ Ab is a new DM-specific autoantibody, which is particularly specific for anti-MDA5 Ab-positive DM.[24] SFPQ is a multifunctional nuclear protein associated with the human gene expression pathway, RNA production and processing, and viral infection.[24,25] Because both SFPQ and MDA5 have important roles in viral infection, the recurrent disease in our patient's case may suggest an association with viral infection.