ASXL3 is a Polycomb group protein that functions as a non-catalytic component of the PR-DUB complex, a multiprotein epigenetic regulator 12. The PR-DUB complex catalyzes deubiquitination of histone H2A monoubiquitinated at lysine-119, affecting genes involved in development, cell communication, signaling, cell proliferation, and chr18 remodeling 12. ASXL3 contains characteristic ASXN, ASXM, and PHD domains, with a proline-rich domain distinguishing it from other ASXL family members 3. Pathogenic variants in ASXL3 cause ASXL3-related disorder, also termed Bainbridge-Ropers syndrome, a neurodevelopmental disorder characterized by global developmental delay (97%), intellectual disability, hypotonia (88%), feeding difficulties (76%), and distinctive craniofacial features including downslanting palpebral fissures, hypertelorism, and tubular nose (93%) 45. The majority of pathogenic variants are de novo truncating mutations occurring in exons 11-12, with loss-of-function mechanisms predominating 65. ASXL3 variants have also been identified in arthrogryposis multiplex congenita and left ventricular noncompaction, expanding the phenotypic spectrum 78. While functional characterization remains limited, current evidence supports haploinsufficiency as the disease mechanism in neurodevelopmental presentations.