EIPR1 (EARP complex and GARP complex interacting protein 1) is a WD40-domain protein that functions as a critical component of endosomal retrieval machinery 1. It mediates recruitment of the GARP complex to the trans-Golgi network and promotes recycling of internalized transferrin receptor through interaction with the EARP complex, thereby controlling early endosome-to-Golgi transport 1. EIPR1 also cooperates with EARP in dense core vesicle biogenesis, essential for proper insulin secretion 2. Pathogenic variants in EIPR1 cause a neurodevelopmental disorder characterized by global developmental delay, microcephaly, ataxia, spasticity, cerebellar atrophy, and neutropenia 2. These variants reduce EIPR1 protein levels and impair its interaction with EARP and GARP complexes, resulting in endolysosomal dysfunction and compromised vesicle trafficking 2. Zebrafish models confirm that EIPR1 is essential for nervous system development and locomotor function 2. Clinically, EIPR1 emerges as a prognostic biomarker in multiple cancers, particularly lung adenocarcinoma, where elevated expression correlates with poor survival and increased invasion 3. Epigenetic regulation of EIPR1 through allele-specific methylation influences psychiatric disorder susceptibility, with altered EIPR1 expression affecting neural development and vesicle trafficking 4. Additionally, EIPR1 genetic variants associate with pain sensitivity 5.