RFT1 (glycolipid translocator homolog) is a multispanning endoplasmic reticulum (ER) membrane protein with N and C termini facing the cytoplasm 1. Its primary function is mediating transbilayer translocation of the heptasaccharide lipid intermediate Man₅GlcNAc₂-PP-dolichol across the ER membrane during N-linked glycosylation 23. This translocation is essential for completing assembly of the Glc₃Man₉GlcNAc₂-PP-dolichol oligosaccharide precursor, which is subsequently transferred to asparagine residues in nascent proteins by oligosaccharyltransferases 2. RFT1 is essential for cell viability in yeast and mammalian systems 1. Mutations in RFT1 cause Congenital Disorder of Glycosylation type 1N (RFT1-CDG), characterized by intracellular accumulation of incomplete dolichol-linked oligosaccharide intermediates and profound N-glycosylation defects 2. RFT1-CDG clinical presentations include typical CDG symptoms and sensorineural deafness 3. Additionally, RFT1 translation is regulated by leucyl-tRNA synthetase 1 in a codon-biased manner; reduced RFT1 expression impairs N-glycosylation and contributes to chemoresistance in intrahepatic cholangiocarcinoma 4. The majority of disease-causing mutations map to highly conserved protein regions 1. Note: RFT1 should be distinguished from riboflavin transporters also designated RFT, which are SLC52 family members 5.