Structure and function in gene patenting

The United States patent system treats DNA sequences as large chemical compounds in determining their patentability. This approach has been helpful to those who seek to patent previously unidentified DNA sequences, but it may prove less advantageous from the perspective of those who elucidate biological functions and disease relevance of previously identified genes. A current controversy over patent rights for DNA sequences encoding leptin receptors provides a useful case study for illustrating some of the issues that are likely to arise in applying doctrine derived from chemical patent cases in the context of gene discovery.