ERT is not a cure for lysosomal storage diseases, and it requires lifelong IV infusions of the therapeutic enzyme.[8] This procedure is expensive; in the United States, it may cost over $200,000 annually.[8] The distribution of the therapeutic enzyme in the body (biodistribution) after these IV infusions is not uniform.[8] The enzyme in less available to certain areas in the body, like the bones, lungs, brain. For this reason, many symptoms of lysosomal storage diseases remain untreated by ERT, especially neurological symptoms.[8] Additionally, the efficacy of ERT is often reduced due to an unwanted immune response against the enzyme, which prevents metabolic function.[8]