Video: Cut-and-paste DNA to cure disease

Mapping the human genome and comparing vast data banks of DNA has helped scientists identify some of the “good” and “bad” mutations that can protect or expose individuals to disease, says Feng Zhang, speaking at the Annual Meeting of the New Champions 2014. According to the US-based researcher, diseases can be prevented and even cured by performing surgery on a person’s DNA by replacing tiny harmful mutations with tiny positive ones.

Here are some quotes from the clip. You can watch the full video at the top of this page.

On recent advances

Back in 2002, it would cost almost $1 billion to sequence a single human genome, but today we can do it for less than $1,000; and with that significant decrease in the cost, we can start to sequence everything from Ebola viruses to the genomes of many, many different individuals.

With the increase in the ability to sequence the human genome, we’ve started to uncover a lot of different mutations that may be involved in disease. There has been exponential growth in the number of publications that describe differences across different populations of individuals. Some of these look at populations of cancer patients and compare them with populations of healthy individuals, and by making these comparisons across large data sets, we can start to infer different kinds of mutations that may contribute to specific kinds of disease risk.

On the surprising power of yogurt

It turns out that the bacteria we use to make yogurt has evolved a very particular mechanism: to be able to defend itself against viral infection. Bacterial cells, just like us, get bombarded by viruses. To fight them, they evolved a way to remember previous viruses, so when those viruses come into the cell again, they are able to destroy the invaders. These memories are formed in a small nucleic acid sequence called RNA, and the RNA can recognize the DNA sequence just by pairing with it.

So we use this mechanism just like molecular scissors … to make a cut in a very well-defined location within the human DNA. We can literally cut and paste, and splice in the sequence that we want to either fix or introduce into the human genome.

Is this a cure for HIV?

Between 1% and 6% of Caucasians carry a particular mutation in a protein called CCR5 … and individuals who lack this particular protein are immune to HIV infection. This is a protective mutation, and is something we can harness and put into a person who has HIV to make their cells no longer susceptible to the propagation of the virus. The proof of concept is in an individual: Timothy Brown. Timothy was infected with HIV and the treatment he received was a bone marrow transplant where the blood cells in his system were replaced with blood cells that lacked the CCR5 receptor. As a result, he has been declared completely cured of HIV.

On the future

This gives us hope that if we develop these therapies to be able to put in or remove protective and deleterious mutations respectively, then we have the potential to be able to treat very devastating diseases that we don’t have any way of treating today.

More about genetics
The breakthrough that can switch on any gene
What birdsong can teach us about evolution
Why we must embrace genetics
DNA’s double-edged sword

Author: Feng Zhang is a core member of the Broad Institute of MIT and Harvard, USA.

Image: A scientist prepares protein samples for analysis in a lab at the Institute of Cancer Research in Sutton, July 15, 2013. REUTERS/Stefan Wermuth