By Drs. David Niesel and Norbert Herzog, Medical Discovery News
The future of treating genetic diseases may lie within the emerging field of molecular surgery. It may seem impossible to imagine doing surgery on such a micro level, but the development of a molecular technique called genome editing can be used to correct genetic defects within cells.
We are always looking for new weapons in the fight against genetic diseases, which can have devastating effects. We inherit our genes from our parents, and each of us has variations in the sequence of our genes that make us unique. However, mutations as small as a single base (these are A, T, C, G) in your DNA can lead to life-altering diseases such as sickle cell anemia or cystic fibrosis.
In laboratories around the world, new molecular tools are being developed that can be used to correct such genetic mutations and therefore provide a cure for the diseases they cause. Using molecular surgery, doctors could theoretically "fix" the genetic defect.
A recently developed molecular technique that enables scientists to edit genes is called CRISPR-Cas. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. These are short, repetitive sequences in our genomic DNA that are spread throughout the genome. Cas is a protein that acts as molecular scissors.
This works by creating a short piece of RNA -- a genetic molecule like DNA -- that targets a specific gene in the lab. Then the RNA and the Cas protein are introduced into cells, where the RNA provides a guide to the gene to be modified then acts as a target for the cutting action of the Cas protein. This can be used to remove, or more importantly in this case, to replace a defective gene with a functioning one.
So far, experiments in the laboratory show CRISPR-Cas is able to repair the genetic mutation that causes sickle cell anemia and also cystic fibrosis mutations. In addition, it has been used to prevent and slow the spread of HIV. This technology also has the capability to correct multiple mutations simultaneously, which will be crucial to curing diseases that arise by more than one genetic mutation. The next step will be clinical trials to evaluate CRISPR-Cas's potential to correct mutations and treat disease directly in humans. For some diseases, correcting the mutation in even half of the affected cells could prevent symptoms and essentially cure the disease.
As with any technology that provides the ability to change the human genome, scientists must consider the ethics of molecular surgery seriously. For example, could parents alter an embryo or child's genes so they are more athletic or have a specific eye color? The range of options when changing genes is almost limitless and profound. To that end, scientists from around the world have already met to start developing a system of guidelines for this type of research. It will take our scientists, medical ethicists and citizens to decide the boundaries of this powerful and far reaching technology.
CRISPR-Cas and other methods of molecular surgery have a profound potential to cure diseases and could alter our future health in ways we can only imagine.
Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.