Vol. 1, No. 5 — “Thank you for waiting, this time of year is so busy with everyone trying to land a Fall birthday. First of all, great news: all three of the embryos are viable! One will have blue eyes and the other two green. One of the green-eyed candidates has a predisposition to Alzheimer's but will be in the 95th percentile for height and lean muscle mass.
We will edit out the Alzheimer risk of course but the rest is up to you. Let us know your preference on stature and eye color, then we’ll move through any catalog options for appearance and intellectual capacity you’re interested in.”
While the world wrings its collective hands over the implications that highly intelligent computers may have on us in the future, a quaint little technology named CRISPR has been making headways since its invention in the early 2010s. Never heard of it? It’s a programmable genetic editor which works on living organisms. Yeah, that old chestnut.
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. That doesn’t mean anything to me either and it doesn’t really matter. Unless you’re a genetic biologist, any technical article about CRISPR is basically inscrutable. Let’s stick to the basics: what can it do and what makes it special?
First of all, genes are just sequences of DNA (deoxyribonucleic acid), a molecule that is unique to every living organism. Some of these sequences are short and some are long. There are different ways to measure it but humans have about 20,000 genes.
DNA consists of only four different ingredients: adenine, guanine, cytosine, and thymine and we represent those with the letters A, G, C, and T. Everything that has ever lived can be represented by a (very) long series of these four letters. Human DNA is several billion letters in length. While that sounds big, it’s still less than one gigabyte of data.
This makes DNA our “software” so to speak. But where a computer is programmed with ones and zeroes, we are programmed with A, G, C, and T. In some circles, it’s referred to as “wetware”, the software of the body. If we have blue eyes, that specific piece of our DNA code might read “GATCC” but if our eyes are green it reads “GACTT.” The same goes for our metabolism or our ability to fend off the flu, etc. These are all represented by sequences of letters in our DNA.
Now, wouldn’t it be nice to be able to modify bits of DNA to elicit some desired change? Like eliminating a person’s predisposition to Parkinson’s? Or erasing male-pattern baldness? Science has been pursuing this goal since the 1960s with initial successes in the 1970s. However, the methods developed were highly specific, always targeting a single gene to modify for a single purpose. Every time a new gene was targeted, a completely new method needed to be devised. This is like building a new computer from scratch for every application you want to run. It can be done, but it doesn’t scale. Enter CRISPR.
Jennifer Doudna and Emmanuelle Charpentier invented CRISPR in 2012 while researching how bacteria fight off viral infections. They noticed that a certain type of protein, Cas9, would cut and modify DNA structures in the bacteria to remember which viruses it had seen before. Then they figured out a way to instruct the actions of the protein. After that, nature takes its course. Unleash a pre-programmed CRISPR-Cas9 payload into some cells and you can do whatever you want with their DNA.
CRISPR can be programmed to recognize any specific gene sequence and replace it with a different sequence. It is a general tool to modify DNA and does so with extreme precision. Previous methods could replace sequences successfully but would always modify unrelated codes inadvertently. Not desirable, to say the least. No one hires a home renovation crew that does excellent work on kitchens and living rooms but will always accidentally turn another random room into a reptile terrarium.
Their invention netted them the Nobel Prize but also ignited a huge ethical debate around genetics. Having advanced in capability much quicker than expected, they themselves called for a moratorium on its use in 2015. Debate increased but work continued. In 2018, it was announced that two babies were born with CRISPR-modified genes. The biophysicist behind it had modified the DNA in twin girls to immunize them against HIV. One of their parents was an HIV carrier and had given consent to perform the procedure. The scientist involved in the HIV case went to prison. Little is known about the children’s health.
In 2019, the scientific community called for another moratorium. Now, more specifically, on editing heritable traits. Editing one human’s DNA should not be passed on for generations. This is an important distinction as well to the work that made the COVID-19 vaccines possible. These operated on mRNA. RNA is not permanent. DNA is.
Outside of humans, what else has CRISPR been used for? It was used to modify tomatoes so they had higher levels of GABA which can lower blood pressure. It was also used to decrease leptin in a species of fish. Leptin is a hormone that signals the brain when you’re full. Without it, the fish grew much larger than they normally would. Both of these products have been for sale in supermarkets since 2021.
Many other examples exist where CRISPR was used to eliminate disease susceptibility in a certain crop or increase its resistance to cold or heat, etc. In general, to make better use of resources and increase the profitability of crops.
So how close are we to designer humans? Well, the fictional example up top contains less fiction than you think. Fertility clinics are already sequencing the DNA of viable embryos to let you pick eye color and screen for things like Downs syndrome. Now, editing the embryos? That’s still a ways off…at least through official channels.
The beautiful thing about CRISPR is also what makes it a bit scary. It’s quite easy to use. Research labs around the world now have a reliable tool to research cures for genetic disorders. For example, treatments using CRISPR are already available for sickle cell anemia. Patients with this disease currently have a life expectancy of less than 55 years. There are cancer treatments in the works. Neurodegenerative disease treatments and the list goes on. The upside is tremendous!
The real question is: how long before we have DIY DNA kits? Like a chemistry set from the toy store. The instructions might not show you how to build anything dangerous but if all the ingredients are there, it’s only a matter of time.
What a topic switch for you. You have a great technique of explaining hard subjects, like DNA and CRISPR. Maybe comes from trying to explain midwestern culture! Keep writing.