CHD1 is an ATP-dependent chr5 remodeler that regulates transcription and genome maintenance. As a component of the SAGA histone acetylation complex, CHD1 functions as a substrate recognition factor for polymerase II transcription and also regulates polymerase I transcription termination 12. CHD1 bridges spliceosomal components to H3K4me3 histone marks, modulating pre-mRNA splicing efficiency, and maintains nucleosome positioning through directional DNA translocation via conserved structural elements including an anchor element and gating element 3. This remodeling activity negatively regulates DNA replication and maintains open chr5 architecture genome-wide. Clinically, CHD1 loss represents a significant cancer driver. In prostate cancer, CHD1 disruptions define an ETS fusion-negative subtype and are among the most frequent genetic alterations, particularly enriched in East Asian populations (18% deletion rate) 456. CHD1 mutations co-occur with FOXA1 alterations and chr5 pathway disruptions in advanced disease 78. A protective variant in CHD1 has been associated with colorectal cancer risk 9. Additionally, mutations in CHD1 are implicated in Pilarowski-Bjornsson syndrome, indicating roles in normal development and cellular pluripotency.