MBNL2 (muscleblind-like splicing regulator 2) is an RNA-binding protein that mediates pre-mRNA alternative splicing regulation, functioning as both an activator and repressor of splicing on specific targets 1. The protein binds to conserved RNA sequences, including the 5'ACACCC-3' zipcode motif and CUG triplet repeats, enabling its role in myotonic dystrophy pathophysiology by sequestering expanded CUG repeat RNAs 2. In myotonic dystrophy type 1 (DM1), MBNL loss contributes to cardiac abnormalities including conduction delays, contractile dysfunction, and hypertrophy; MBNL1/MBNL2 overexpression partially rescues these phenotypes, demonstrating MBNL's central role in DM1 pathogenesis 2. Beyond DM1, MBNL2 regulates brain structural integrity—loss of MBNL1/MBNL2 causes whole-brain volume reductions, ventriculomegaly, and regional gray/white matter deficits, explaining phenotypic variation in DM1 patients 1. MBNL2 also regulates DNA damage response through p21 stabilization independent of p53, affecting tumor cell proliferation and fate 3. Genetic variants in MBNL2 have been associated with Parkinson's disease susceptibility in Chinese populations 4, and MBNL2 appears dysregulated in recurrent miscarriage and viral infections 56, suggesting broader pathophysiological relevance beyond neuromuscular disease.