Wiskott-Aldrich syndrome protein forms nuclear condensates and regulates alternative splicing

Wiskott-Aldrich syndrome is caused by mutations in WASP, but the underlying mechanisms remain to be explored. Here the authors reveal that WASP deficiency results in aberrant RNA splicing, and that WASP regulates the transcription of splicing factor genes and co-transcriptional RNA splicing via a phase-separation process that involves splicing factors and nascent RNA.