There’s a CRISPR genome editing boom of sorts going on with as many as 20 human trials being undertaken in several countries. However, researchers may be ignoring some serious drawback of the genome editing which made it easy and affordable for laboratories to target nearly any sequence.
The capability to precisely modify the gene of any organism is a promising prospect for treating and curing diseases such as cancer, leukemia, and HIV/AIDS. However, there is growing evidence that CRISPR could alter regions of the genome which researchers are not targeting, according to Dr. J. Keith Joung of Massachusetts General Hospital, a report from StatNews.com said.
At a recent American Society of Hematology’s workshop on genome-editing, Joung showed some 150 experts from industry and academia an example where CRISPR is supposed to edit the VEGFA gene on chromosome 6. Vega stimulates the production of blood vessels, including those used by cancerous tumors.
Joung said studies have shown that the CRISPR can hit genes on every one of the other 22 human chromosomes.
“Although each CRISPR has zero to a dozen or so ‘known’ off-target sites (where known means predicted by those web-based algorithms), Joung said, there can be as many as 150 ‘novel’ off-target sites, meaning scientists had no idea those errors were possible,” the StatNews.com report said.
The issue of off-target effects is important there is the possibility that genome editing could inadvertently disable a tumour-suppressor gene or activate a cancer-causing gene.
Consider the possibility of and off-target effect where two different chromosomes are joined in a phenomenon called translocation. Translocation is the cause of chronic myeloid leukemia and other conditions.
Off-target effects occur because CRISPR has two parts. The RNA part targets the site in the genome specified by the RNA’s string of nucleotides. The enzyme cuts the genome at this site.
However, a genome can have more than one site where the same string of nucleotides appears.
The cutting enzyme of CRISPR does not stop at one cut. The enzyme “still has the energy to bind with an off-target site, so it can still cleave those sites,” said Joung.
To read the whole story, click on this link.