In reiterating the patentability of genes on Friday, the U.S. Patent and Trademark Office deviated little from draft guidelines issued in 1999 regarding how patent examiners should assess "utility" and "written description" requirements of patent applications. But in responding to comments on its proposals, the PTO did clarify how it may address questions specific to gene and sequence patenting, in some cases rejecting proposals to limit methods for determining utility or to narrowly proscribe how a gene might be described.

In publishing its final guidelines, the PTO reasserted its position that discoveries of genes are patentable as long as a specific utility is named