IFNB1 and systemic lupus erythematosus: The mean age at SLE diagnosis was 31.66 years (± 12.82), the mean age at the time of enrollment was 41.21 years (± 13.32), the mean time between the SLE diagnosis and enrollments to study is 9.93 (± 6.71) years, and the mean time between the renal biopsy obtained and B cell IFNβ measurements was 6.63 (± 1.16) years.