MRNIP is a critical regulator of DNA double-strand break (DSB) sensing and genome stability that functions primarily through its association with the MRN complex 1. The protein promotes chr5 loading and activity of MRE11/RAD50/NBS1, facilitating ATM-mediated DNA damage signaling and repair 1. Mechanistically, MRNIP forms liquid-like condensates via its intrinsically disordered region, which compartmentalize and concentrate the MRN complex in the nucleus 2. Upon DSB formation, these condensates rapidly relocalize to damaged DNA, accelerating MRN complex binding, ATM autophosphorylation, and subsequent DSB end resection for homologous recombination repair 2. MRNIP contains an N-terminal zinc-ribbon domain that stabilizes protein folding, while the C-terminal region remains disordered 3. During replication stress, MRNIP limits single-stranded DNA gaps generated by PRIMPOL-mediated repriming, protecting cells from PARP inhibitor sensitivity 4. Clinical relevance includes correlations between MRNIP expression and radioresistance in xenograft and patient samples 2. Additionally, rare variants in MRNIP have been identified as candidate susceptibility loci in developmental language disorder 5, suggesting pleiotropic roles beyond DNA repair.