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Hope for Genetic Disease : Surgical Genetic Therapy by Cas9—an enzyme that repairs DNA-

Updated: Oct 19, 2022

CAS9 is enzyme with an amazing ability to slice DNA with exquisite precision and specificity in cutting DNA we want to target.

Then we can paste DNA in to replace what we have removed. Indeed CRISPR/Cas9 has become a common genome editing tool in both basic and medical research. It induces targeted DNA double-strand breaks (DSBs) that are commonly repaired by non-homologous end-joining (NHEJ), which leads to gene disruption and knockout. One of the most exciting recent developments in genetic engineering is CRISPR-Cas9 (CRISPR).

CRISPR derives its name from "clustered regularly interspaced short palindromic repeats," genomic sequences that microbes use to defend themselves against viral attacks.

CRISPR-Cas technology allows scientists to edit genes and manipulate gene expression with a level of ease that was not possible using other methods. Importantly, it also allows researchers to edit genes within living organisms, a fact that supports the use of CRISPR-Cas in a far-reaching range of applications from basic research to the development of novel therapies and other biotechnology products.

Enhancing CRISPR-based HDR by Cas9 fusion proteins can improve and trigger repair locally at the cut site, without causing generalized interruption in the cellular DNA repair process and thus improving the safety and specificity of the editing.
Example : Cas9-POLD3 fusion accelerates the initiation of cut repair . POLD3 is a part of the replicative polymerase δ, and it seems that POLD3 fusion improves genome editing by speeding up the removal of Cas9 from the cut site (Clarke et al., 2018). The faster Cas9 removal results in early recruitment of the DNA damage response machinery to the break and speeds up the DNA repair progression.

The 2020 Nobel Prize for Chemistry was awarded to Emmanuelle Charpentier and Jennifer Doudna for the development of this method for genome editing.

Researchers are looking to CRISPR as a technique for editing out genetic defects that result in sickle cell disease, cystic fibrosis, hemophilia, and muscular dystrophy, and for developing more targeted and effective cancer treatments. One study showed that adult rats engineered to have a genetic form of blindness could be treated using CRISPR gene therapy (Berry et al. 2019). The goal is to someday have patients' diseased cells removed, "fixed" with CRISPR, and then returned to their bodies to treat various conditions or have diseased organs be treated directly with CRISPR.

Therefore this ENZYME CAS9 has the capacity to cut altered DNA sequences,

responsible for genetic disease, ready to be repaired. Nevertheless CRISPR is revolutionizing many aspects of biotechnology and scientific research.

This is the present and future of THERAPY.

F. Conforto MD

Critical Care Physician Anesthesiologist

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