Many key variables in the domains of sociodemographics, SLE specific, comorbidities, baseline haematology/biochemistry/immunology and treatment data were collected by ≥75% respondents including the 1997 American College of Rheumatology (ACR) Classification Criteria (83%), SLE Disease Activity Index-2000 (82%), current treatment (100%), drug name, dose, frequency and start date (75–100%) and complement C3/4 (94%). This evidence concerns the gene C3 and systemic lupus erythematosus.