Great. Thank you, Kristen. In terms of how we select within our portfolio, I'll go back to the initial decisions on building our portfolio, and that was very much based on a disease approach. Looking at each disease, again, a number of years ago began with a list of nearly 1,000 rare diseases; we brought that down to under 100, and then of course, we looked at the unmet need, the technical feasibility of gene therapy broadly, we looked specifically at the technical fit of combining the Penn Gene Transfer Technologies with Amicus protein engineering, to look at size of, patient populations, we look at availability of natural history, I think all of that competitive dynamics as well. And then when we look at our portfolio today, if you take, for instance, the Fabry and the Pompe gene therapy programs, those continue to be key strategic priorities for Amicus, we're moving those forward. We're moving them as fast as the science and the manufacturing and analytical technologies are allowing. And there if you recall, back in November, we announced our Fabry drug candidate selection, again combining the Amicus and Penn Technologies. And that was 12 to 18 months ahead of our original internal projections. So, we have to make sure that we have the financial capital, the human capital, and the manufacturing capacity available, which we did by reordering some earlier parts of our priority. So in effect Fabry gene therapy has leapfrogged Pompe based on technical feasibility and our ability to advance it within all of those disciplines. With that, Jeff maybe if you can comment on how we think about the different pieces of the technology, including route of administration?