The function of Ensembl gene identifier ENSG00000169733 (RFNG, RFNG O-fucosylpeptide 3-beta-N-acetylglucosaminyltransferase) is as follows. Glycosyltransferase that initiates the elongation of O-linked fucose residues attached to EGF-like repeats in the extracellular domain of Notch molecules. Modulates NOTCH1 activity by modifying O- fucose residues at specific EGF-like domains resulting in enhancement of NOTCH1 activation by DLL1 and JAG1. May be involved in limb formation and in neurogenesis. {ECO:0000250|UniProtKB:O09009, ECO:0000250|UniProtKB:O12972, ECO:0000250|UniProtKB:Q9R1U9}.