Article Text: DNA Prime Editing

A new way of editing the code of life could correct 89% of the errors in DNA that cause disease, say US scientists.

The technology, called prime editing, has been described as a "genetic word processor" able to accurately re-write the genetic code.

It has been used to correct damaging mutations in the lab, including those that cause sickle cell anaemia.

The team at the Broad Institute say it is "very versatile and precise", but stress the research is only starting.

Can't we already edit DNA?

Prime editing is the latest advance in the field of gene editing, which is developing at an incredible pace.

Our DNA is the instruction manual for building and running our bodies. It is in nearly every one of our cells.

Being able to tweak DNA through gene editing is already transforming scientific research, promising to revolutionise medicine and asking deep moral and ethical questions after the creation of babies who were gene-edited to have protection from HIV.

Much of the excitement has centred on a technology called Crispr-Cas9, which was developed just seven years ago.

It scans DNA for the right spot and then, like a microscopic pair of scissors, cuts it in two.

This creates the opportunity to edit the DNA.

However, the edits are not always perfect and the cuts can end up in the wrong place. Both issues are a problem for using the technology in medicine.

The promise of prime editing is precision.

How does prime editing work?

The study, in the journal Nature, used prime editing to accurately insert or delete sections of DNA; as well as correct typos in a single "letter" out of the three billion that make up the human genetic code.

One of the researchers, Dr David Liu, said: "You can think of prime editors to be like word processors, capable of searching for target DNA sequences and precisely replacing them.

"Prime editors offer more targeting flexibility and greater editing precision."

Prime editing is like pressing Ctrl-F to find the bit of text you want to change, then pressing Ctrl-C and Ctrl-V to copy over the new text (or the command key if you're a mac user).

The technology uses a lab-made sequence of genetic code. This has two roles, one is to find the specific part of the DNA you want to edit and the other contains the change you want to make.

This is paired with an enzyme (called a reverse transcriptase) which copies the relevant edits over into the DNA.

It was developed by researchers at the Broad Institute of MIT and Harvard in Massachusetts.

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