MYT1L is a neuron-specific transcription factor essential for neuronal identity and development. As a transcriptional repressor, MYT1L binds the 5'-AAGTT-3' core motif in gene promoters and recruits a SIN3B-containing multiprotein complex to silence non-neuronal genes during neuronal differentiation 1. Notably, MYT1L functions as a 'many-but-one' repressor, simultaneously suppressing multiple somatic lineage programs while preserving neural gene expression 1. It also represses negative regulators of neurogenesis, including Notch pathway components like HES1 1. Combined with ASCL1 and POU3F2, MYT1L efficiently reprograms fibroblasts into functional induced neurons 2. MYT1L deficiency primarily impairs maturation programs and repressive gene expression rather than activation, suggesting haploinsufficiency drives disease pathology 3. Pathogenic MYT1L variants—including missense, truncating mutations, and 2p25.3 microdeletions—cause neurodevelopmental disorder characterized by developmental delay (95%), intellectual disability (70%), behavioral disorders (98%), and epilepsy (23%) 4. De novo mutations recur in autism spectrum disorder 5, and mutations alter human cortical interneuron differentiation and electrophysiological properties 6. The gene has also been associated with fibromyalgia susceptibility 7.