Enzyme replacement therapy is the most straightforward. If you have an enzyme that is not working, we give your body that enzyme back. They are infused every week or every 2 weeks with that enzyme. There are a couple of drawbacks to enzyme replacement therapy.  The threshold of effectiveness may be different with each disorder and site. Because enzyme replacement therapy has to target the lysosomal and enter the lysosome where it’s supposed to degrade those substrates, the bioavailability of the enzyme that is delivered into the blood can differ depending on the tissue that you target.  The other issue with enzyme replacement therapy is it doesn’t cross the blood-brain barrier, so for those neurological manifestations in some LSDs enzyme replacement therapy might not be the best option.