EMC1 is a core subunit of the endoplasmic reticulum membrane protein complex (EMC) that functions as a membrane protein insertase and chaperone 1. EMC1 mediates energy-independent insertion of newly synthesized membrane proteins into the ER membrane, with particular capacity for proteins containing weakly hydrophobic transmembrane domains or destabilizing features 2. The protein facilitates both cotranslational insertion of multipass membrane proteins and post-translational insertion of tail-anchored proteins, controlling proper N-exo topology critical for G protein-coupled receptor function 3. Mechanistically, EMC1 engages transmembrane domains and modulates their orientation within the lipid bilayer during productive assembly 1. EMC1 mutations cause significant clinical disease. Biallelic variants lead to neurodevelopmental delay, cerebellar atrophy, and visual impairment 4, while de novo monoallelic variants also cause neurodevelopmental delay, seizures, and cerebellar degeneration with glial-specific vulnerability 4. EMC1 mutations are associated with retinal degeneration—Emc1 knockout in photoreceptors recapitulates retinitis pigmentosa phenotypes through mislocalization of rhodopsin and progressive rod and cone degeneration 5. EMC1 variants additionally contribute to congenital heart disease and craniofacial malformations through disrupted neural crest cell development and impaired WNT signaling 6. The gene represents both a membrane protein biogenesis factor and a novel disease locus for inherited neurological and retinal conditions.