It doesn't matter that cDNA is similar to something found in nature. The fact is that DNA complementary to the mature spliced mRNA sequences of the BRCA1/2 genes does not exist in nature.
This really sounds like hair splitting to me. Along the lines of saying "well, your software patent is for a program that is stored on a GMR disk platter. Mine's stored in NAND flash, and that's never been done before!"
If the sequence is logically equivalent but stored on a different medium, how is that novel? The invention of the new medium or new techniques for transcribing between media may be, but the sequence itself isn't.
Not exactly. DNA and RNA are structurally only slightly different, but functionally, in the context of a biological system, they are very different. A technical analogy might be RAM vs disk.
True, but that's a tenuous argument. You can't prove that a particular gene has been reverse transcribed and that its cDNA is therefore a naturally-occurring product, unless that cDNA is essential to the virus' life cycle. To invalidate the patent, you would probably have to actually observe the natural reverse transcription of the complete sequence.
In any case, the original point I was trying to make was that the natural occurrence of the mRNA does not make the cDNA a naturally occurring product.
If the sequence is logically equivalent but stored on a different medium, how is that novel? The invention of the new medium or new techniques for transcribing between media may be, but the sequence itself isn't.