MED13 (mediator complex subunit 13) is a critical component of the Mediator complex kinase module that regulates RNA polymerase II-dependent transcription 1. The protein functions as part of the CDK8 kinase module (CKM), which reversibly associates with the core Mediator complex to modulate transcriptional activity 2. Structurally, MED13 contains a large intrinsically disordered region (IDR) that directly occludes RNA polymerase II/MED26 binding sites, leading to transcriptional repression when the kinase module is bound 2. Beyond its nuclear transcriptional role, MED13 has secondary cytoplasmic functions in stress response, where it translocates to promote processing body assembly and autophagy for cellular survival 3. Disease relevance is significant, as de novo mutations in MED13 cause intellectual developmental disorder, autosomal dominant 61, characterized by developmental delays, speech disorders, autism spectrum features, and various dysmorphisms 1. Mutations cluster in functionally important regions affecting protein ubiquitination and degradation 1. Additionally, MED13 serves as a genetic modifier in neurodegenerative diseases, particularly α-synuclein-associated neurodegeneration in Parkinson's disease, where it interacts with glycolytic pathways to provide neuroprotection 4. The gene also shows frameshift mutations in microsatellite-unstable gastric and colorectal cancers 5.