Mucopolysaccharidosis Type II (MPS II), also known as Hunter syndrome, is a rare genetic disorder caused by a mutation in the gene that is responsible for making the enzyme iduronate-2-sulfatase (IDS). IDS is needed to break down long chains of sugar molecules known as mucopolysaccharides. These sugar molecules are cellular waste products. As they build up in tissues, like the central nervous system (CNS), they cause progressive damage to these tissues and to many organs in the body, including the brain.
In severe forms of MPS II, early developmental milestones in a child may be met, but delays become apparent by 18 to 24 months, with decline reported around six and a half years of age. Children with MPS II may also show symptoms of severe behavioral effects. There remains a significant unmet medical need to prevent further decline in cognition and other neurological aspects of the disease.
Our investigational therapy, RGX-121, is designed to use the AAV9 vector to deliver the IDS gene directly to the CNS. We believe that once the AAV9 vector delivers the gene to cells, the cells can begin making the needed IDS enzyme, potentially preventing further progression of cognitive deficits.
We are advancing RGX-121 in preclinical (animal) studies, and plan to seek approval for a clinical trial thereafter.