London - It has been less than five years since it was discovered, yet the gene-editing technique known as Crispr/Cas9 has become a recognised “game-changer” in the field of genetics.
The technology uses “guide” molecules to identify precise positions on the structure of DNA which can then be cut and spliced with a bacterial enzyme. Crispr/Cas9 is able to edit genes at the smallest resolution - down to a single base pair within the sequence of the 3 billion bases that make up the human genome.
Crispr, which stands for “clustered, regularly interspaced, short, palindromic repeats”, is a guide molecule made of RNA, a close cousin to DNA. This is the part of the technology that is made to order for targeting a specific site of interest on the DNA molecule.
It comes attached to Cas9, a bacterial enzyme that cuts the DNA double helix at precisely the required point. It is the combination of Crispr and Cas9 that makes the complex so powerful as a gene-editing tool. Eric Lander, director of the Broad Institute at Harvard University, has said that Crispr/Cas9 holds “great therapeutic potential” in human medicine because of its power to edit precise points within the human genetic code.
T-cells could be edited to remove the membrane proteins used by HIV to gain entry into these vital components of the immune system, or liver cells could be engineered to lower the high cholesterol levels in families with inherited mutations, Dr Lander said.
“However,” he warned earlier this year, “the technology also raises a more troubling possibility: creating children carrying permanent, heritable changes to the human germ-line DNA.”
This is why the US has imposed a moratorium on using Crispr/Cas9 to edit the genomes of human eggs, sperm and embryos.
The Independent