B3GALT6 encodes β1,3-galactosyltransferase 6, a Golgi-localized glycosyltransferase that catalyzes the transfer of galactose from UDP-galactose to galactose-β1,4-xylose residues in the linker region of glycosaminoglycans (GAGs), particularly heparan sulfate and chondroitin sulfate 1. This enzyme is essential for proteoglycan biosynthesis, functioning as the third sugar-adding enzyme in the GAG linkage region 2. B3GALT6 mutations cause spondylodysplastic Ehlers-Danlos syndrome and spondyloepimetaphyseal dysplasia, characterized by severe musculoskeletal abnormalities, craniofacial dysmorphism, and connective tissue fragility 13. These pathogenic mutations reduce protein abundance and eliminate galactosyltransferase activity, leading to deficient GAG synthesis and ultrastructural collagen fibril disorganization 1. Loss of B3GALT6 function results in impaired collagen maturation and altered tissue biomechanics 3. Beyond skeletal disease, B3GALT6 promotes dormant breast cancer cell survival and recurrence through heparan sulfate-mediated FGF signaling, predicting poor patient outcomes 4. Additionally, sulfated GAGs produced via B3GALT6 serve as cellular targets for Candida albicans candidalysin toxin, with therapeutic potential through exogenous GAG supplementation 5.