To cut the most compact part of the genome, there are molecular scissors better than those of the Crispr-Cas9 technique: they are the blades of the Talen technique, five times more efficient in repairing the defects of the most condensed part of the genome, the heterochromatin, whose anomalies can cause diseases such as sickle cell anemia and beta-thalassemia.
This is demonstrated by a study published in the journal Nature Communications by the University of Illinois at Urbana-Champaign.
The results highlight the need to select a wider variety of tools to intervene on the genome: just as in everyday life we use different scissors for sewing, cooking or gardening, so also in genetic engineering we should use different molecular scissors for various portions of the genome on which we intend to intervene. Those of Crispr "represent a very powerful tool that has led to a revolution, but still have some limitations", says the coordinator of the study, Huimin Zhao. His research group discovered this by observing the Crispr and Talen scissors in action on the DNA of living mammalian cells, thanks to a fluorescence microscopy technique that allows them to see the individual molecules. In this way, explains the researcher, "we discovered that Crispr works better on the regions of the genome that are less compact", those of the so-called euchromatin, "while Talen is able to better access the genes found in the more compact regions of the Heterochromatin. We have also seen that Talen is more efficient in editing than Crispr: it can cut DNA and introduce changes more effectively. "