ISG15 and systemic lupus erythematosus: This diverse group of diseases may be genetic/hereditary (e.g., Aicardi-Goutières Syndrome (AGS), ISG15 deficiency, and USP18 deficiency), autoinflammatory [e.g., systemic lupus erythematosus (SLE) with neurological manifestation], caused by congenital and chronic viral infections (e.g., infections with Toxoplasma gondii, rubella virus, cytomegalovirus, herpes simplex virus, hepatitis B and C virus, and human immunodeficiency virus), or without known etiologies such as Degos disease (156–158).