Should I start patenting the cDNAs I've made in the lab?

Jun 13 2013 Published by under Issues in Science

In a unanimous decision today, the SCOTUS struck down patents for genes by ruling against Myriad Genetics in Association for Molecular Pathology vs. Myriad Genetics. The Court, however, did leave some wiggle room for companies to patent cDNAs, or complementary DNA.

"In Myriad, the high court held cDNA is patentable, because it involves actual work in the laboratory and inverts the normal process found in nature. The synthetic DNA is an edited version of a gene, stripped of non-coding regions that the court said makes it “not naturally occurring.”

Critics say even the edited sequences are directly analogous to naturally occurring DNA."

In many labs, cDNAs are routinely made, manipulated, and used for research. cDNA is DNA that is engineered in reverse using messenger RNA (mRNA) as the template. As the above quote alludes, a cDNA is not a carbon copy of its corresponding gene. Interspersed along the length of a gene are regions of non-coding DNA sequence. These are segments of DNA that aren't represented in the sequence of the encoded protein. When a gene is initially transcribed into mRNA some of these non-coding regions, called introns, are included. Introns, however, are ultimately removed by the cell before the mRNA is translated into protein. Since mRNA is used to make cDNA, the introns are excluded from the cDNA sequence.

gene expression

During gene expression, a gene is first transcribed into a primary RNA transcript, which includes non-coding introns (blue). Through a process called splicing the introns are removed from the transcript resulting in a mature mRNA molecule. The sequences found in mRNA are called exons (red and yellow). The mRNA is  then translated into protein. Since cDNA is made from mature mRNA, it will consist only of exon sequences.

Although gene and cDNA are different, they both carry essentially the same DNA sequence for a protein. (It should be noted, however, that many genes encode multiple forms of a protein, for which each form has its own corresponding cDNA.) So, I'm not sure why the "patentable" emphasis is on cDNAs as opposed to making mutations* to the underlying sequence that result in say, new or altered function of a protein. At least there I could see an inventive process happening--or am I missing something here?

*I'm talking about generating novel mutations. Of course, I'm not sure what should happen if said mutations are discovered to be "naturally occurring" after the fact.



5 responses so far

  • Ed says:

    From the footnotes:

    "We express no opinion whether cDNA satisfies the other statutory requirements of patentability."

    They're just saying that, in principle, the process of making a cDNA copy of a particular gene could be patentable. It sounds silly to us because all of the enzymes and reagents we use are ubiquitous, older than we are, and years out of patent (if they ever were). Obviously there's a ton of prior art.

    I suppose, depending how the patent lawyers has this out, that it might mean that a very particular procedure to make cDNA for gene X, including specific primers, could be patentable today. (Primer design is simple, but not entirely "obvious".) That's hardly a big deal though, since there are many ways to accomplish something similar, and such a patent would be so narrow as to be useless.

  • Blaise Pascal says:

    The rest of the decision also covered the very narrow question of the patentability of the genes themselves, not (as Ed is looking at) the process of how to make the genes, or what can be done with the genes afterwards, etc. I assume the same comments apply to cDNA.

    The BRCA1 and BRCA2 genes, by themselves, are not patentable, since they appear in nature. cDNA versions of genes do not appear naturally, so are not excluded from patentability by the "appear in nature" test.

    But what the footnote that Ed quoted points out is that the courts didn't say anything else about the patentability of cDNA, namely novelty or obviousness.

    I suspect that most cDNA is not patentable. If I were to find an interesting gene, and applied standard lab protocols to create a cDNA version of that gene and tried to patent it, I strongly suspect that a judge would decide that taking a natural gene and applying standard lab protocols in a standard way would be obvious to a reasonably skilled practitioner and/or not particularly novel.

    Similarly, I suspect that making custom primers matching a particular gene in the same way that any other lab would make custom primers for any other gene would not be patentable merely because of the sequence of the bases. On the other hand, if I were to design a new tagging system to primers that made them easier to work with/manipulate/etc, then that new tagging system may be patentable.

    IANALOAB, so take this with a grain of KCl.

    • AmasianV says:

      As it stands, are gene variants patentable, insofar as ones that have been lab-generated and not been identified yet in populations?

    • cDNAs don't appear in nature, but mature mRNAs do, granted they do maintain their UTRs. Pascal is correct, its not the cDNA that is novel and patentable, it would be an enhancement such as his hypothetical tagging system. I wonder how the ruling will affect these humanized monoclonal antibodies that biotech is working towards?

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