Scientists have figured out how to edit DNA with a light switch.
That’s a switch activated by light, not the literal switch like on your wall.
We haven’t figured that out yet…
Probably.
Hi everyone, Julian for DNews.
Way way back in the year 2012, scientists started using a gene editing tool called CRISPR/Cas9.
The system worked by harnessing a protein that bacteria use to protect themselves against
viruses.
Yes, bacteria can get viruses, it’s a tough world on the cellular level.
Anyway, this defense worked by intercepting the virus’ DNA with Cas9, a nuclease, or
protein that can cut DNA.
The Cas9 is guided by a strand of RNA that matches some sequence on the virus DNA.
Once it locks on to that section of DNA, Cas9 chops it like Gordon Ramsay.
Probably makes the virus cry too.
I think you see where this is going; if we just rejigger the guide RNA, we can edit the
DNA of anything: crops, animals…
people.
And that’s exactly what we set to doing.
CRISPR is simple and ingenious, plus it can edit several genes at once.
It can edit the DNA of cultured cells or a fertilized egg, meaning entire animals can
be altered.
Because of this, the CRISPR technique has found widespread use in the short time since
its invention.
By the end of 2014 600 research papers had been published mentioning CRISPR.
Private companies are looking to treat cystic fibrosis and sickle cell anemia by changing
just one base pair in the DNA of cells in patients’ bone marrow.
And this is where the ethical issue comes in.
Is it safe and is it ethical to edit the germline of a human being?
After all if you edit the DNA of a person before they’re born, you’re not just editing
that person but all their offspring.
What if a mutation given to them for short-term benefit turns out to have unforeseen consequences
in the long run?
And is it crossing a line to edit an embryo's DNA to change how that person might look or
think before they have a say in the matter?
The ethical questions are tough and it’s up to us as a society to figure out what we
think is right or wrong.
Personally I think so long as we don’t end up with splicers or Indominus rexes, we’re
mostly good.
But the safety issues are a matter of science, and we’re making progress there.
One problem a recent study using CRISPR revealed is the nuclease may not be accurate enough.
The study published in Protein and Cell used CRISPR to modify genes in human embryos that
would cause a blood disorder.
The embryos wouldn’t make it to term anyway because they were fertilized with two sperm
each, but still an unacceptably low number of them survived and carried on the new genes.
If we’re going to use this technique on future people, that number has to be near
100%.
Part of the problem was it appears the Cas9 was off target and modified some genes it
wasn’t supposed to.
You’ll recognize this as the beginning of every zombie movie ever.
But this problem may have just been solved by Alexander Deiters from the University of
Pittsburgh.
Deiters and colleagues have created a Cas9 with an amino acid swapped out for a light-activated
analog.
This means the Cas9 isn’t fully shaped until a light is shined on it.
Once it’s in the right place you hit it with a spotlight, it changes shape, allowing
it to do its job and boom: high precision gene editing is now possible.
The long-term effects and ethical issues remain to be resolved but one hurdle to making the
technique safer has just been cleared.
We may be new to the DNA editing game but that little double helix has been splicing
and dicing for millennia.
Julia explains how virus DNA is part of you here.
What are your thoughts on editing human embryos and DNA?
Is everything on the table or is it totally off limits?
How do you define the gray area in between?
Let us know in the comments or on facebook or twitter, subscribe for more, and I’ll
see you next time on DNews.