BABAM1 (BRISC and BRCA1-A complex member 1) is a structural component of two multi-protein complexes critical for DNA damage response and immune signaling. As part of the BRCA1-A complex, BABAM1 recognizes Lys-63-linked ubiquitinated histones H2A and H2AX at double-strand breaks (DSBs), facilitating recruitment of the BRCA1-BARD1 heterodimer to DNA lesions 1. The complex possesses deubiquitinase activity that removes Lys-63-linked ubiquitin chains from histones, with BABAM1 required for complex integrity and DSB localization. Within the BRISC complex, BABAM1 maintains stability of BABAM2 and supports Lys-63-linked deubiquitinase activity, including deubiquitination of NUMA1 to promote mitotic spindle assembly 23. BABAM1 also regulates interferon signaling through IFNAR1 deubiquitination, enhancing receptor stability and activity while dampening responses to bacterial lipopolysaccharide 2. Functionally, BABAM1 phosphorylation at Ser29 by mTORC2 initiates DNA damage response and repair in glioblastoma cells 1. Genetic variants in BABAM1 associate with breast, ovarian, prostate, and lung cancer susceptibility in multiple populations 4567, with specific isoforms mediating cancer risk through transcriptomic mechanisms 7.