Abbreviations: BMT, bone marrow transplantation; CDG, congenital disorder of glycosylation; CSF, cerebrospinal fluid; ERT, enzyme replacement therapy; F, fibroblast; MPS, mucopolysaccharidosis; MRI, magnetic resonance imaging; P, plasma; TfIEF, transferrin isoelectric focusing; U, urine; VLCFA, very long chain fatty acids. Here, TF is linked to mucopolysaccharidosis.