The mutations observed in MDS frequently occur in genes associated with six types of biological functions: DNA damage response (e.g., TP53), epigenetic/chromatin modifiers (e.g., EZH2), transcription factors (e.g., RUNX1), RNA splicing (e.g., SF3B1), signal transduction (e.g., NRAS), and cohesin complex (e.g., STAG2; ref. 6). The gene discussed is STAG2; the disease is myelodysplastic syndrome.