The goal of this observational study is to investigate different phenotypes among patients with SLE and to compare with matched general population controls. The main questions we aim to answer are: A To investigate if subgroups of patients with systemic lupus erythematosus (SLE) defined by autoantibodies, genetic predisposition or biomarkers, rather than the present diagnostic entities account for the high risk of premature vascular disease. B To perform in depth studies of selected patient groups to shed light on the autoimmune mechanisms behind antiphospholipid (aPL) antibodies and nephritis and their association to vascular disease in SLE and APS Participants will be investigated in person by a nurse and a rheumatologist. Data on previous and present disease characteristics, anthropometric measurements and health related quality of life (according to selfreported questionnaires) will be entered into a data base. Blood samples (plasma serum and DNA), urine and saliva is stored in a corresponding biobank. Researchers will compare identified subgroups of SLE patients to each other and to matched population controls.