ET Bureau Dec 28, 2019, 11.20 PM IST
As with newspapers, it is very hard to edit if you can’t read,” says George Church, a renowned geneticist at Harvard Medical School, about the genome. When the human genome was first sequenced in 2003, it had taken 13 years of work and cost nearly $3 billion. Since then, the cost has plummeted to as low as $600. And the time required for sequencing has shrunk to a few weeks.
These changes have enabled the rapid rise of geneediting methods, particularly Crsipr (clustered regularly interspaced short palindromic repeats), this decade. A term often bandied about as a magic solution in a range of fields, Crispr was first found in bacteria.
When a virus attacks a bacterium, the latter stores portions of the virus’s genetic code within its genome. This helps it to recognise future viral attacks, and Crispr-linked enzymes called Cas9 disarm the virus by slicing its DNA. “We can probably recode the genome of any species to make it resistant to all viruses using 300 to 4,000 edits,” says Church, a pioneer in Crispr research.
Crispr can be used to fix genetic mutations in humans to treat rare diseases as well as to edit a plant’s genome to increase yields or to make it more resistant to droughts. Some early studies are being done on Crispr’s efficacy in treating certain cancers and sicklecell disease, an inherited blood disorder.
While these studies have shown promise, it is too early to declare Crispr a success in these treatments. A new alternative to Crispr-Cas9, called prime editing, is said to be more precise in inserting DNA sequences. “The future is editing, but it is not yet clear exactly which kind of editing,” notes Church.
Crispr could also be the biggest leap in agriculture since genetically modified crops, and is being used to increase yields of rice, advance harvests of tomato, change the colour of carrots and make citrus fruits resistant to a particular disease. There are also ambitious efforts underway to eventually eliminate malaria by using Crispr to make mosquitoes resistant to the malaria parasite or to reduce female mosquito populations since only they are able to transmit malaria, leading to the extinct of the species.
However, these advances in genetic editing are not without their ethical challenges.
A Chinese scientist, He Jiankui, claimed last year that he had created the world’s first gene-edited babies using Crispr, to make them resistant to HIV, although that could make them more vulnerable to other diseases. He invited condemnation from around the world and exposed the dangers of unregulated gene editing.
There is no disputing the potential of geneediting techniques in curing diseases or transforming agriculture, but we have to resist the urge to play God.
This story is part of the 'Tech that can change your life in the next decade' package