WASHINGTON - Fragments of RNA and DNA, including Expressed Sequence Tags (ESTs), may be patented but such patents are not likely to have a negative impact on subsequent efforts to patent the entire gene, according to a letter written to NIH Director Harold Varmus by Patent Commissioner Bruce Lehman.

The correspondence supports comments made to BioCentury last week by John Doll, head of the biotechnology group at the Patent and Trademark Office (PTO), in which Doll indicated that the first patents on ESTs may be issued in a few months (see BioCentury, April 7).