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Turquoise-colored chromosomes

In another of a long line of studies showing unintended effects of gene editing, the CRISPR-Cas gene editing tool has been found to cause the loss of whole chromosomes and genomic instability in mouse embryos.

The finding is yet another nail in the coffin for human germline (heritable) gene editing with CRISPR, though there are plenty of people who persist in advocating it. The study comes hot on the heels of another, which found that editing human cells with CRISPR caused chromothripsis, an extremely damaging form of genomic rearrangement that results from the shattering of individual chromosomes and the subsequent rejoining of the pieces in a haphazard order.

The genetic material in certain (“eukaryotic”) microorganisms, plants, animals and humans exists in bundles known as “chromosomes”. In organisms that sexually reproduce (plants, animals, humans), two copies of each chromosome are inherited, one from each parent. Loss of a chromosome results in gene imbalance and function, leading to severe inherited diseases and is also frequently seen in cancer. So any procedure that induces chromosome loss is bad news and should be avoided... see more