The one crucial takeaway from the Supreme Court ruling on DNA patents

Last week, the Supreme Court issued a ruling on patenting "natural" DNA. It was a ruling so confusing that even Justice Scalia admitted he didn't feel qualified to understand it. Luckily, science journalist Maggie Koerth-Baker has spelled it all out (literally) for you.

What's at stake in the ruling is whether companies can patent "natural" strings of DNA, which to many people seems like an obvious "no." Saying you can patent a string of DNA you found is like saying, "I found an arm so I can patent it now." Even though arms are very special and cool, you don't get to patent one just because you found it on somebody's body. Likewise for genes you find in somebody else's genome. Right? Well, sort of.

The court did rule that you can't patent a sequence of DNA that you found in somebody's genome. Which is great, but it doesn't actually prevent companies from patenting (and selling the products of) the most useful parts of that sequence of DNA. That's where the odd parts of the ruling come in, and where Koerth-Baker's explanation is vital.

Writes Koerth-Baker:

The new ruling doesn't cover all DNA. It's still perfectly legal to patent synthetic DNA, and the court documents referred specifically to complimentary DNA (aka cDNA).

This is where things get murky. Complimentary DNA is a thing that can be both natural and synthetic. And, as a laboratory creation, it's an important step in a common method of replicating naturally occurring DNA . . .

DNA, you'll remember, is like a twisted ladder, a double helix. Split the ladder in half, add a few chemical changes, and you get RNA. This molecule can do many things, but one of the big ones is moving genetic information from DNA to ribosomes, the cellular factories that build proteins. To do that, you need a special kind of RNA, messenger RNA (mRNA). This is basically just a condensed version of your genetic information — half a strand of DNA, but with all the bits that don't build proteins snipped out.

It's sort of like taking

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and cleaning it up so that what you're left with is the much-more-understandable

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(Which is something that happened.) Thus condensed, mRNA takes the genetic information to ribosomes and, together, they start turning it into functional proteins. This is how DNA gets translated into, say, insulin, or muscle tissue, or the keratin that makes up your hair.

But scientists have another use for mRNA. If they want to make lots of copies of a specific gene, they can essentially put the mRNA in reverse, using it to create a whole strand of DNA. This lab-created DNA is nearly identical to the stuff that occurs naturally. The only difference is that, like the mRNA, it's lacking all the stuff that doesn't build proteins. And that is what counts as cDNA. Just to clarify, according to the ruling last week, you can't patent the DNA for

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but you can still patent the DNA for

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That fact has left a lot of people with a lot of confusion about what this ruling will actually mean in the real world.

Especially because most patents on genes will be for the cDNA (the useful stuff) rather than the DNA (the raw, unedited molecule).

Read the rest of the article over at BoingBoing