Researchers used single-molecule imaging to compare the genome-editing tools CRISPR-Cas9 and TALEN. Their experiments revealed that TALEN is up to five times more efficient than CRISPR-Cas9 in parts of the genome, called heterochromatin, that are densely packed. Fragile X syndrome, sickle cell anemia, beta-thalassemia and other diseases are the result of genetic defects in the heterochromatin.
source https://phys.org/news/2021-01-genome-editing-tool-talen-outperforms-crispr-cas9.html
