Thus, in a cohort of 117 paediatric lupus cases (<16 y, median age 9 y) in which 20% had familial SLE, drawn from Europe, Asia and Africa, a diagnostic yield of 7% (eight moFL cases) were identified (C1QA, C1QC, C2, DNAS1L3, IKZF1). The gene discussed is C2; the disease is systemic lupus erythematosus.