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Zinc finger nucleases have also been used in a mouse model of haemophilia [31] and a clinical trial found CD4+ human T-cells with the CCR5 gene disrupted by zinc finger nucleases to be safe as a potential treatment for HIV/AIDS. [32] ZFNs are also used to create a new generation of genetic disease models called isogenic human disease models.
In the early 2000s, German researchers began developing zinc finger nucleases (ZFNs), synthetic proteins whose DNA-binding domains enable them to create double-stranded breaks in DNA at specific points. ZFNs have a higher precision and the advantage of being smaller than Cas9, but ZFNs are not as commonly used as CRISPR-based methods.
In addition, zinc fingers have become extremely useful in various therapeutic and research capacities. Engineering zinc fingers to have an affinity for a specific sequence is an area of active research, and zinc finger nucleases and zinc finger transcription factors are two of the most important applications of this to be realized to date.
Off-target genome editing refers to nonspecific and unintended genetic modifications that can arise through the use of engineered nuclease technologies such as: clustered, regularly interspaced, short palindromic repeats ()-Cas9, transcription activator-like effector nucleases (), meganucleases, and zinc finger nucleases (ZFN). [1]
However they can control where these edits will occur (i.e. dictate the target site) through using a site-specific nuclease (previously Zinc Finger Nucleases & TALENs, now commonly CRISPR) to break the DNA at the target site. A summary of gene-targeting through HDR (also called Homologous Recombination) and targeted mutagenesis through NHEJ is ...
TALENs are less efficient than CRISPR/Cas9, but they are still a useful tool for genome editing. Zinc finger editing, using zinc finger nucleases Natural genetic engineering (NGE) has been proposed by molecular biologist James A. Shapiro to account for novelty created in the course of biological evolution.
Early techniques relied on meganucleases and zinc finger nucleases. Since 2009 more accurate and easier systems to implement have been developed. Transcription activator-like effector nucleases (TALENs) and the Cas9-guideRNA system (adapted from CRISPR) are the two most common.
Zinc finger nucleases are genetically engineered enzymes that combine fusing a zinc finger DNA-binding domain on a DNA-cleavage domain. These are also combined with CRISPR-CAS9 or TALENs to gain a sequence-specific addition, or deletion, within the genome of more complex cells and organisms. [17]