What was once a very mysterious gene now has all kinds of people trying to figure out how it works. What it does and how it works are questions that are all the more exciting as we look at these new and improved tools for understanding human genetics. With the advent of the gene-editing tool CRISPR, scientists can now create custom nucleases to edit specific regions of the human genome to make certain gene variants work better.
Now, many, including myself, are excited to learn about the potential of such a tool. The potential is huge, but what’s even more exciting is that in order to take advantage of it, scientists have to figure out how the gene works, which is incredibly difficult.
When I first heard about the potential of CRISPR, I was skeptical because as a layperson I didn’t understand what a gene was, but I now know that genes are the same as chromosomes in the human being, and that the gene editing works like a DNA splicing or recombination. Basically, with CRISPR, scientists are able to use CRISPR to target a specific location in the human genome so that the gene editing can take place.
This is the first time that CRISPR has been used to edit genes in humans, and it’s amazing that it has been possible to do this for the first time in humans. The gene editing is called CRISPR/Cas9, which stands for “clustered regularly interspaced short palindromic repeats/CRISPR-associated 9”.
The first time that CRISPR has been used to edit genes in humans was with the gene editing tool called mhs2, which was developed by one and the same team. It’s pretty cool because it’s basically a CRISPR-compatible tool for editing genetic material in human cells. The only thing I can think of doing that would be to just edit the sequences of the genes in the body of a mouse to make sure that it actually works.
I’m all for doing this in humans, but it’s not a very good idea because you’d have to edit the genomes of human embryos in mice, at a very high rate of mutation. The good news is that mhs2 is a human gene editing tool, and it’s not that hard to engineer a CRISPR-mutation to edit the genes in humans.
the idea is pretty simple. You have a pair of complementary DNA (cDNA) sequences that you want to edit. One of these DNA sequences contains a “stop” mutation that stops transcription at that point, and the other DNA sequence is a gene that you want to edit. The only problem is that you’d have to design your “stop” mutation so that it does not make any biological sense, so that would require some kind of reverse engineering.
We’ll be using a CRISPR-based gene editing technique in mhs2, in which a DNA strand is cut by the enzyme Cas9. We’d then add a single guide RNA (sgRNA) to this cut strand. The sgRNA will then guide the Cas9 to a site on the genome.
The problem is that most CRISPR-based gene editing techniques are based on cutting DNA at specific points and not cutting it so we can change the DNA sequence. In mhs2 one of the Cas9 endonucleases has a “guide” sequence at the cut site. A guide RNA is used to guide the Cas9 endonuclease.
The guide RNA is a DNA segment that recognizes the DNA sequence and the Cas9 endonuclease. In mhs2 you can change the DNA sequence by editing the DNA sequence. In the case of mhs2 this means replacing the guide RNA sequence with the new guide RNA sequence. This allows our scientists to change the DNA sequence with a precision that would require a human being to manipulate the DNA sequence.
