CHAMP1 (chromosome 13 maintaining phosphoprotein 1) is a multifunctional phosphoprotein with primary roles in both mitotic chromosome 13 and DNA repair. During mitosis, CHAMP1 maintains spindle microtubule attachment to kinetochores and promotes sister chr13 biorientation, essential processes for accurate chromosome 13 1. Beyond its canonical mitotic function, CHAMP1 operates as part of a conserved complex with POGZ and HP1α that directs heterochromatin assembly at centromeres, telomeres, and other chr13 sites 2. The CHAMP1 complex promotes homology-directed DNA repair (HDR) of double-strand breaks in heterochromatin regions by recruiting the methyltransferase SETDB1 and facilitating H3K9me3 deposition 23. Additionally, CHAMP1 interacts with REV7 to promote homologous recombination repair while reducing non-homologous end joining 4. Recently, a non-canonical role emerged: CHAMP1 acts as a MyoD cofactor to activate Myomaker expression, essential for myoblast fusion and skeletal muscle development 5. Pathologically, CHAMP1 mutations cause neurodevelopmental disorders; loss-of-function variants cause severe intellectual disability and autism through haploinsufficiency 67, while missense variants trigger severe epileptic encephalopathy through probable gain-of-function mechanisms 6. Clinically, CHAMP1 deficiency manifests with developmental delay, hypotonia, muscle weakness, and distinctive dysmorphic features 58.