TREX1 and familial chilblain lupus: Malfunctioning of TREX1 is associated with a broad spectrum of inflammatory and autoimmune diseases which are apparently independent, such as Aicardi-Goutieres syndrome (AGS), cryofibrinogenemia, familial chilblain lupus (FCL), systemic lupus erythematosus (SLE) and retinal vasculopathy with cerebral leukodystrophy (RVCL) [17,19,20,21,22].