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.

Related Reading:

Patents on Nature

 

 

Crossposted at Scientopia

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