Making sense of the confusing Supreme Court DNA patent ruling

Nine people who have not recently made any sweeping judgements about biotechnology.

Last week, I told you about the US Supreme Court ruling that made it illegal to patent naturally occurring DNA. In that article, I talked briefly about the fact that the new ruling doesn't cover all DNA. It's still perfectly legal to patent synthetic DNA, and the court documents referred specifically to complementary DNA (aka cDNA).

This is where things get murky. Complementary 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. All of which leaves some holes in the idea that the Supreme Court ruling is a simple "win" for open-access science, patent activists, and patients. After all, if you can't patent a gene, but you can patent the laboratory copy of the gene, what's that mean? It's sort of like not being able to patent a novel, but being able to patent a copy of its contents that's had all the white space removed. It seems like everybody is a bit confused by this. So I wanted to take a moment to at least clarify what cDNA is and what some people, on different sides of the science/law/biotech divides, are thinking about it.

It starts with some stuff you learned back in junior high — how information from your DNA gets turned into actual working proteins.

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

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

but you can still patent the DNA for

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

At The LA Times, Amina Kahn reported that Myriad Genetics — the company that had claimed a patent on two genes involved in breast cancer risk, and which ostensibly lost at the Supreme Court — actually saw their stock price go up in the wake of the ruling. That could be because a big, profit-affecting question (Can the company patent the genes?) got solved and, now, the company could turn around and patent cDNA versions of the genes. Sure, they lose some of their monopoly on the breast cancer industry, but they still have something special and aren't totally out of the game, financially. In fact, with a Supreme Court ruling in their pocket, Myriad's business model may now be more stable, since what they can and can't do is now more spelled out.

That seems to be a perspective shared by biotech consultant Susan Finston. The ruling, she writes, does open up the market to allow more companies to sell their own tests for breast cancer risk — but it's also not some kind of wide-scale smack down against the biotech industry.

All in all, the Myriad decision should not adversely affect the patentability of a broad swath of gene-based inventions. The ability of a patent applicant to avoid the law of nature exception, i.e, to “create or alter” DNA – whether via cDNA or through use of plasmids – limits the prospective impact of the case.

On the other hand, Myriad shouldn't get too comfortable in its new position, writes Lyle Denniston at the SCOTUS blog.

The opinion said in a footnote, however, that the Court was not actually ruling that cDNA is specifically entitled to a composition patent, and noted that the federal government had raised other objections under patent law to that phenomenon.

In fact, Justice Scalia's wrote a side note saying that he, himself, couldn't make any statements on the science beyond the simple fact that naturally occurring DNA is not something that a company creates, and thus, is not patentable. That's been interpreted by some people (including some of the commenters on the story last week) as an expression of some anti-science "I don't believe in DNA" position. But I'm not sure it is. Denniston, for instance, interprets it as something closer to Scalia saying that has absolutely no idea whether he believes DNA and cDNA should count as different things — he simply doesn't know enough about the science to say. And that's actually a pretty reasonable position to take. Especially when you consider the fact that cDNA can happen in nature, without the help of scientists. HIV, for example, can turn its own RNA into cDNA. That's how it makes copies of itself.

Taken all together, it's safe to assume that this is not the last time the Supreme Court will be talking about the patentability of cDNA. This is not a given yet.

The basic lesson that you should take away seems to be this: The Myriad Genetics ruling is really, really narrow. Yes, it prevents companies from patenting a gene that they just happened to find in the human body (or anyplace else). But it leaves plenty of room to patent genetic information — and it leaves plenty of room for future court battles over what genetic information can and cannot be patented. This is a big court case that only reduced uncertainty a tiny bit.

*Please note that I am simplifying the creation of RNA here. I've edited it to make it more clear that RNA is not simply DNA split in half. There's more to it than that. I hope this will not give people a clear and quick mental picture without being misleading.


  1. one helluva lot of legal fuzziness hinges upon the definition of “natural”.   just one definition “without artificial intervention [of humans]” typically ends up becoming meaningless once humans feel the need to adjudicate something being natural or not.  (~legalistic quantum mechanics)

  2. “DNA, you’ll remember, is like a twisted ladder, a double helix. Split the ladder in half, and you get RNA.” – No, you get single-stranded DNA. There’s an entire copying step to be done to get mRNA, which is chemically different. This ‘transcription’ is followed by the splicing to get rid of non-coding regions (introns) and other editing to make the final mRNA.  (If you think about it, you can’t use the original single strand of DNA – once it’s chopped up you wouldn’t be able to use it as a storage device any more.)

    1. yep.  plus the little matter of:  “in RNA, uracil base-pairs with adenine and replaces thymine during DNA transcription”

      1. Thank you for letting me know that my simplification had drifted into oversimplification. I’ve gone back and tried to clarify that RNA isn’t just DNA split down the middle. I’m trying to simplify the process here for the sake of a clear mental image and getting to the point (cDNA) faster. But I also don’t want to be misleading. 

  3. So Eli Whitney can’t patent “natural” cotton in the field, but legally he owns separated cotton fiber. What could possibly go wrong?

  4. Great analysis, thanks.  I do stand by my original assessment, though:  Myriad can’t patent BRCA genes, but they can build Cylons.

  5. As long as you’re tweaking, it’s complementary DNA. Complimentary DNA is DNA the bank gives you when you open a checking account.

  6. “cDNA can happen in nature, without the help of scientists. HIV, for example, can turn its own RNA into cDNA.That’s how it makes copies of itself.”

    OK guys, new plan: Someone patent the cDNA of HIV and then if it tries to reproduce, we sue! We’ll destroy its whole business model!

  7. In the DNA > mRNA > cDNA process, the introns in the DNA  are removed by the cell when the mRNA is made, so the cDNA does not have introns either.  Many genes with mutations that cause disease have got 15 or more introns, and the mutations can be in the intron because they screw up the mRNA processing.  ( … skipping a few details)  Without a patent on the DNA intron sequences, they can’t monopolize the diagnostcs. 

  8. The fact that it’s this hard to make sense of the ruling just proves how broken the patent system is. When something that is meant to bolster innovation is instead stifling it:

  9. The problem with most of the analyses I have seen so far is that whether describing so-called “natural” DNA/gene or cDNA the focus has been on the molecule itself, i.e., is it naturally occurring or is it “man-made”. I feel this is fallacious to begin with since what is actually important is the INFORMATION that is encoded by those molecules. If you go back to that as the most fundamental of precepts, then there is no difference between the information encoded in the cDNA version of the gene and the information  encoded in the original (natural) DNA molecule. This is why I think the hair-splitting of the Supreme Court is not based on any real biological distinctions but rather on a flimsy compromise that keeps the murk alive.

  10. I thought that one of the main issues with the BRCA-Myriad patent was that they were the only ones aloud to conduct research on this gene, hence they are the only ones that know the specific mutations linked to cancer. The patent of the gene by itself  (in this case) wasnt the big deal (you are not going to get a demand for having the gene, all humanity has it), but the research done with it and the information linked to cancer. With the new supreme court decision, the research is now open to everyone, and it doesnt matter if the cDNA is still patented. 

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