FLVCR1 is a major facilitator superfamily membrane transporter that functions as a plasma membrane choline and ethanolamine transporter in mammals 1. The protein mediates cellular uptake of these essential nutrients for phospholipid biosynthesis via the Kennedy pathway, with choline and ethanolamine binding to a common aromatic binding pocket through distinct molecular interactions 23. Loss of FLVCR1 severely impairs choline metabolism, causes mitochondrial structural defects, and triggers integrated stress response activation through heme-regulated inhibitor kinase 1. Flvcr1 knockout mice are embryonic lethal, partially rescued by choline supplementation, underscoring its critical developmental role 1. Clinically, FLVCR1 mutations cause hereditary sensory and autonomic neuropathies (HSAN) and posterior column ataxia with retinitis pigmentosa (PCARP) 24. FLVCR1 expression is hypoxia-responsive, regulated by HIF2α and ETS1, linking it to erythropoiesis and vascular adaptation 5. Additionally, FLVCR1-AS1, an antisense lncRNA, is dysregulated in multiple human cancers and affects cell proliferation, migration, and metastasis 6. Genome-wide association studies identify FLVCR1 genetic variants associated with plasma choline levels in population studies 7, establishing its importance in human metabolic homeostasis.