Us Ruling on Breast Cancer Genes is A Mixed Blessing

One can't patent a naturally occurring DNA sequence--but one can patent an altered product made from that sequence. That, in short, is the ruling handed down last week by the US Supreme Court on the validity of patents for the breast cancer genes BRCA1 and BRCA2. Widely billed as a decision on whether human genes can be patented in the US, the ruling actually applies to DNA from any species. In a unanimous ruling, the Supreme Court decided that simply isolating a natural DNA sequence is not a patentable invention. However, it upheld Myriad Genetics' claims on complementary DNA (cDNA) derived from the BRCA genes. These are sequences made in the lab from RNA--the template used to produce the proteins that genes code for. This cDNA lacks the non-coding introns found in the full sequence of a gene and is therefore not a product of nature--which is why the court ruled that it can be patented.