Gene therapy for Huntington's Disease?
Hi there, This year I learned I'm gene positive for HD. I'm relatively young and have a repeat mutation of 42. What is the latest research and realistic hope in terms of genetic therapy as a cure for me?
Kat - And here's Harriet Johnson with this month's listener question. Harriet - Listener Cari says, "This year, I learned I'm gene positive for Huntington's disease. I'm relatively young, so I'd like to know what is the latest research and realistic hope in terms of a genetic therapy as a cure for me." To answer, here's Nobel Prize winner, Craig Mello from the Howard Hughes Medical Institute at the University of Massachusetts.
Craig - That is a very difficult question to answer. Right now, these therapies are based on RNA interference which uses the body's own small RNA silencing system. Every cell in our bodies has basically a search engine system, much like we use for browsing the internet. Several years ago, scientists learned how to enter search queries into that search engine and when this search engine finds a target, it can use the sequence information to very precisely identify a piece of the genetic information and turn it off. And now, therapies are now beginning to move into the clinic that are based on entering search queries into the cell's own searching machinery and then directing it to a desired target - in this case, the Huntington's gene. It's not a cure. It's a therapy and the way that this is being delivered would be using a viral vector. In this case, we put a virus to work for us. It delivers into the brain cell directly a small gene that expresses the RNA that enters into this search query machinery I told you about. So, we sort of hijack the cell's own machinery to try to turn off this disease gene. Now, that of course is going to need to be tested further in animals. So there are safety concerns that need to be tested - that's going to take a few more years. Then it will enter clinical trials - that'll take a couple of years, maybe more, then gradually, into bigger clinical trials. So, we're talking about maybe a 10-year horizon before you see a lot of people potentially getting this therapy. There are additional new things coming such as this new technology called CRISPR. One of the benefits of CRISPR would be that it could permanently destroy and inactivate the diseased allele. However, there are a lot of safety concerns with CRISPR in getting it into the cells. Delivery is even more challenging. It's a totally different mechanism that's not endogenous even to human cells. It's something that bacteria have and we're going to have to put the machinery for CRISPR into the human in order to do this. So, this is years away.
Kat - Thanks to Professor Craig Mello for that answer. And if you've got any questions about genes, DNA and genetics, just email them to me at firstname.lastname@example.org.