CCDC186 (coiled-coil domain containing 186) is a protein essential for dense-core vesicle (DCV) maturation in the trans-Golgi network of neurons and endocrine cells 1. The protein functions in small GTPase binding and vesicle cytoskeletal trafficking, facilitating the transport and proper maturation of DCVs, which are specialized organelles responsible for storing and releasing neurotransmitters and hormonal molecules 2. Loss-of-function variants in CCDC186 result in marked downregulation of gene expression and structural alterations affecting protein-protein interactions 2. Biallelic mutations in CCDC186 cause a novel autosomal recessive neurodevelopmental disorder characterized by seizures, developmental delay, epileptic encephalopathy, frontotemporal atrophy, hypomyelination, recurrent infections, failure to thrive, and endocrine disturbances including severe hypoglycemia and reduced cortisol or growth hormone levels 132. Clinical presentations typically manifest with neonatal onset 1. CCDC186 was identified as a candidate disease gene in a large diagnostic sequencing study and has now been confirmed through multiple case reports and functional studies demonstrating pathogenic effects of mutations 413. These findings establish CCDC186 as a critical mediator of neurodevelopmental and endocrine function.