Sampaio EP, et al. – Experts wanted to characterize the molecular mechanism of a novel mutation at the SUMO (Small ubiquitin–related modifier) motif on STAT1 (Signal transducer and activator of transcription 1). Results highlighted this mutation as the first pathologic identification of the critical role of sumoylation in STAT1 function and disease. In view of the current data, they suggested a potential target for STAT1 therapeutic modulation in GOF (Gain of function) disease.