BBB	Blood-Brain Barrier
IDS	Iduronate 2-Sulfatase (Elaprase™)
GAG	Glycosaminoglycan
LC-MS/MS	Liquid Chromatography-Tandem Mass Spectrometry
HS	Heparan Sulfate
DS	Dermatan Sulfate
CSF	Cerebrospinal Fluid
TfR	Transferrin Receptor
MPS II	Mucopolysaccharidosis II
ETV	Enzyme Transport Vehicle
D0A0	4,5 unsaturated uronic acid residue-N-acetyl glucosamine, HS ∆UA-GluNAc
D0S0	4,5 unsaturated uronic acid residue-glucosamine-N-sulfate, ∆UA-GluNS
D0a4	4,5 unsaturated uronic acid residue-N-acetyl galactosamine, 4-O-sulfate, ∆UA-GalNAc4S
HSCT	Hematopoietic Stem Cell Transplant
ERT	Enzyme Replacement Therapy
Nf-L	Neurofilament Light Chain
TfRmu/hu KI	Chimeric human/mouse Transferrin Receptor Knock-In mouse