The short version of the Myriad ruling is a distinction between two kinds of DNA. The Supreme Court, in Association for Molecular Pathology v. Myriad Genetics, held that a segment of naturally occurring DNA is a product of nature and is not eligible for a patent under 35 U.S.C. 101 merely because it has been isolated. The same opinion held that complementary DNA — cDNA, synthesized in the lab from messenger RNA and lacking the non-coding introns of the natural gene — is patent-eligible because it is not naturally occurring. One molecule the human body already makes; the other is an engineered construct. That line is the entire holding.

The patents at the center of the case claimed the BRCA1 and BRCA2 genes, whose mutations are associated with hereditary breast and ovarian cancer. A representative grant in the family is U.S. Patent 5,747,282, “17Q-linked breast and ovarian cancer susceptibility gene,” granted May 5, 1998, and assigned to entities including the University of Utah Research Foundation. Its claim 1 recites an isolated DNA sequence coding for a BRCA1 polypeptide. The legal question was whether locating, sequencing, and isolating that gene — undisputedly a significant scientific achievement — created something eligible for a patent, or whether the claim still reached the natural product itself.

"The judicial exceptions (also called “judicially recognized exceptions”) are subject matter that the courts have found to be outside of, or exceptions to, the four statutory categories of invention, and are limited to abstract ideas, laws of nature and natural phenomena (including products of nature)."— USPTO, MPEP 2106, source

Why isolating a gene was not enough

The Court's reasoning, as the USPTO summarizes it in MPEP 2106's products-of-nature discussion, is that the information content and the nucleotide sequence of the isolated BRCA gene are identical to the gene as it exists on the chromosome. The act of severing chemical bonds to isolate the segment did not change what the claim covered: the genetic information itself, a product of nature. Because the four statutory categories of invention exclude “products of nature” as one of the judicial exceptions, a claim to isolated naturally occurring DNA falls outside Section 101 no matter how much work isolating it required. The eligibility question turns on what the claim covers, not on the effort or ingenuity of the isolation.

cDNA came out differently for a concrete structural reason. When researchers build cDNA from a gene's messenger RNA, the resulting molecule contains only the exon (coding) portions; the introns present in the genomic gene are removed. That arrangement of nucleotides does not exist in nature, so cDNA is not a product of nature and is eligible — except, the Court noted, in the rare case where a very short sequence has no intervening introns to remove, leaving the cDNA indistinguishable from the natural DNA. The distinction is therefore not between “natural” and “man-made” in the abstract, but between a molecule whose sequence matches nature and one whose sequence was created by human intervention.

The cDNA holding is easy to misread as a loophole, but it follows from the same product-of-nature logic applied in the other direction. The test the Court used asks whether the claimed molecule exists in nature in that form. Isolated genomic DNA does, because isolation does not alter the sequence; cDNA generally does not, because the removal of introns produces a nucleotide arrangement the cell never assembles as a standalone molecule. The eligibility outcome therefore tracks a concrete structural fact about each molecule rather than a policy judgment about gene patenting in general. That is why the decision can simultaneously refuse a patent on the isolated BRCA1 gene and uphold eligibility for a BRCA1 cDNA construct — the two molecules are not the same thing under the Court's test, even though they encode the same protein.

What Myriad did and did not decide

Myriad is narrow in an important way. The Court addressed composition-of-matter claims to DNA molecules; it did not hold that method claims, applications of new knowledge about a gene, or claims to novel non-naturally-occurring nucleotide arrangements are categorically ineligible. The decision sits alongside Mayo v. Prometheus in the modern eligibility line and is one of the cases MPEP 2106 cites when it defines the products-of-nature exception. For the biotech patent estate, the practical effect was to redirect claiming strategy away from the isolated natural sequence and toward cDNA constructs, engineered variants, vectors, and specific methods of use — claim formats that recite something the body does not already make.

For anyone reading a gene-related patent today, Myriad is the reason a claim's exact wording matters more than its title. A claim to “isolated DNA” encoding a natural protein and a claim to a cDNA construct encoding the same protein look similar on the page and are treated very differently under Section 101. The first reaches a product of nature; the second reaches a human-made molecule. Reading the independent claim, not the abstract, is what tells you which side of the Myriad line a given patent falls on.

The Myriad line also reshaped how the broader genetic-diagnostics estate is drafted and valued. After the decision, claims that once would have recited an isolated naturally occurring sequence were redirected toward subject matter the test treats as eligible: engineered constructs, expression vectors, host cells carrying recombinant material, primers and probes designed with non-natural modifications, and method claims tied to specific non-routine techniques. The shift is visible in the classification neighborhoods these patents occupy — recombinant and genetic-engineering subgroups rather than claims to the bare gene. For a portfolio analyst, the lesson is that the eligibility regime does not merely decide individual disputes; it steers where a field's claiming activity migrates, because applicants draft toward the formats that survive Section 101 review.

This article reports what the statute, the MPEP, and the cited patent record state; it is a description of the eligibility framework, not legal advice, and outcomes in any specific dispute depend on the precise claims and the full record.