MLLT1 (ENL) is a chr19 reader protein that plays critical roles in transcriptional regulation and leukemogenesis. The protein contains a YEATS domain that recognizes and binds to acetylated and crotonylated lysines on histones, serving as an epigenetic reader 1. MLLT1 functions as a component of the super elongation complex (SEC) and undergoes phase separation to enhance SEC recruitment and drive transcriptional elongation 1. In normal development, MLLT1 is essential for embryonic viability, as targeted disruption in mice causes embryonic lethality prior to 8.5 days post-conception 2. The gene is broadly expressed in murine tissues except liver and myeloid cell lines 2. In disease contexts, MLLT1 is a frequent fusion partner in MLL-rearranged acute leukemias, particularly acute lymphoblastic leukemia, where MLL-ENL fusions occur in 31% of MLL-rearranged cases 13. The YEATS domain is essential for leukemic cell proliferation and survival, making it a potential therapeutic target 4. Additionally, MLLT1 mutations found in Wilms tumor patients enhance phase separation and transcription, driving aberrant gene expression programs 1. The protein also participates in a transcriptional control module with KAT6A, where KAT6A-catalyzed H3K9 acetylation is recognized by MLLT1's YEATS domain 5.