Rewriting Genomes using CRISPR/Cas9

by Dinesh Puppala


CRISPR                    Clustered Regularly Interspaced Short Palindromic Repeat

Cas9                         CRISPR-associated nuclease 9

CRISPR-Cas9 is a new genetic modification technique that is generating extraordinary buzz among life sciences researchers. The Institute of Genetic Medicine recently held a CRISPR-Cas9 symposium for the Johns Hopkins community to share knowledge and resources about this new technology in the field of genetics.

Gene editing is a type of genetic engineering technique in which DNA is inserted, replaced, or removed from a genome using artificially engineered nucleases. CRISPR-Cas9 isn’t the only technology capable of editing genes, but researchers consider it easier to use than other methods including Zinc Finger Nucleases (ZFNs), Transcription Activator-Like Effector Nucleases (TALENs), Meganucleases, and other tools. Recently, using CRISPR-Cas9 technology, Chinese scientists modified monkey genes that regulate metabolism, immune cells, stem cells, and sex. “CRISPR-Cas9 technique allows for the creation of animal models of human diseases in mere months, a process that typically takes multiple years with traditional methods”, said Tim Harris, Senior Vice President of Precision Medicine at Biogen Inc. There are a lot of model organisms that researchers use to study disease, notably mice. For some kinds of disease research, especially neuropsychiatric disorders, animals more closely related to us would be preferable. CRISPR has become a leading technique in research due to its ease, efficiency, and cost.

The possibilities for this technology include genetic medicine and genetically modified organisms of all forms: plants, animals, and microbes. However, CRISPR/Cas9 also comes with inevitable ethical and technical hurdles. Initially, the challenges included figuring out the best way to deliver the editing machinery to the cells it was targeting. Although CRISPR is faster and easier to use than other gene-editing techniques that doesn’t mean it’s more accurate. Off-target cuts to DNA can occur when the sequence is similar but not identical to the guide RNA. This could have unintended and potentially deleterious health consequences. This can also make biomedical research more complicated with unknown off-target effects, which are unwanted characteristics of unknown origin that can make interpreting results much more difficult. Ethical concerns were raised when CRISPR-Cas9 was used to repair the genes that cause beta thalassemia in 86 human embryos obtained from a fertilization clinic. The work raised fears that gene editing could be used to tweak babies in many ways before they were born. A group of biologists including the inventor of the CRISPR approach has called for a worldwide ban on the use of this technique in humans in any way that could be passed down to offspring, as the technique could be used to enhance qualities like intelligence or physical appearance in developing so-called “designer babies.”

Patent Dispute

The University of California, Berkeley and Massachusetts Institute of Technology (MIT) researchers have been arguing over the patent rights to the CRISPR-Cas9 technology. In April, lawyers of the UC Board of Regents asked the United States Patent and Trademark Office to consider again the patents that were given to the Broad Institute of MIT and Harvard. According to their legal team, the rights to the process belong to the team off Jennifer Doudna, Professor of Chemistry and Molecular and Cell Biology at the UC Berkeley.



  1. Why Gene-Editing Technology Has Scientists Excited, WSJ June 1st 2015
  2. MIT and UC Berkeley Researchers argue over Disputed Patent Rights to CRISPR-Cas9: Uncover Michigan
  3. Johns Hopkins Tackles Genome Editing with CRISPR/Cas9 Symposium: Biomedical Odyssey

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