STAT4 and systemic lupus erythematosus: For example, variants of Signal Transducer and Activator of Transcription 4 (STAT4), have displayed association with nephritis, ischaemic stroke, severe renal insufficiency and a younger age at disease onset17–20 as well as an increased overall risk of organ damage.21 For the majority of SLE susceptibility loci however, no links to specific disease subphenotypes have been demonstrated.