Scientists have discovered a set of rules that can guide the precision of genome editing in human cells using the CRISPR/Cas9 tool.

In a new study, scientists analyzed the effects of CRISPR genome editing at 1491 target sites across 450 genes and found a pattern that can predict outcomes based on a simple set of rules.

These rules were published in the journal Molecular Cell.

Safe And Efficient CRISPR Genome Editing

Last month, Jiankui He, a scientist from China, shocked the world when he declared that he created the world's first CRISPR babies. At a conference in Hong Kong, he revealed that he deactivated the CCR5 to give the children immunity against HIV/AIDS.

The experiment received intense criticism from the scientific community around the world for many reasons. Based on the document that He has presented, the twin girls might have developed new mutations, the effects of which remain to be seen.

Because of its unpredictable nature, the scientific community has rightfully been careful about the applications of the technology on human cells. The new set of rules will enable scientists around the world to predict outcomes and use CRISPR with better precision and efficiency.

"Until now, editing genes with CRISPR has involved a lot of guesswork, frustration and trial and error," explained Paola Scaffidi of The Francis Crick Institute in London and lead scientist behind the study. "The effects of CRISPR were thought to be unpredictable and seemingly random, but by analyzing hundreds of edits we were shocked to find that there are actually simple, predictable patterns behind it all."

The team also discovered that how "open" or "closed" the target DNA is will also affect the outcome of the gene editing. To allow modification of a "closed" gene, scientists explained the need to add compounds to force the DNA to open up for the Cas9 to scan the genome.

CRISPR Use In Clinical Setting

If proven, the new set of rules will enable the use of the technology in a clinical setting to treat all kinds of disorders by correcting the disease-causing mutations inside a patient's body.

"By bearing these rules in mind when designing our guide RNAs, we can maximize the chances of getting the desired outcome of a specific gene edit — which is particularly important in a clinical context," added Anob Chakrabarti, co-author of the study.