The patient generally exhibited the following clinical manifestations: (1) skin and mucous membrane involvement (facial butterfly erythema, chilblain‐like erythema, EM, alopecia, oral ulcer, and photosensitivity) (2) blood system involvement (leukopenia, anemia, thrombocytopenia) (3) proteinuria (>0.5 g/24 h) (4) positive immunological indicators (positive ANA, positive anti‐dsDNA antibodies, and hypocomplementemia) (5) proteinuria and lupus transaminitis. Here, BTG3 is linked to erythema multiforme.