washington

The US federal committee that debates new gene-therapy protocols is proposing to expand its remit beyond just experiments involving recombinant DNA.

The Recombinant DNA Advisory Committee (RAC) of the National Institutes of Health (NIH) plans to publish a new definition of recombinant DNA this summer in the Federal Register, for discussion and possible adoption at a meeting in September.

The change could broaden the committee's charge to reflect a changing and widening field in which an increasing variety of gene-manipulation technologies are challenging traditional notions of genetic engineering.

For instance, technologies are emerging for exploiting RNA — molecules involved in passing on the messages encoded in genes — for purposes such as blocking viral gene transcription. And it is hoped that oligonucleotides, which are tiny stretches of machine-made DNA, may soon be used to correct inherited diseases by substituting for a deficient gene.

A 1976 definition still used by the RAC defines recombinant DNA as “molecules that are constructed outside living cells by joining natural or synthetic DNA segments to DNA molecules that can replicate in a living cell”. Experiments that the RAC should monitor, its guidelines say, are those “involving the deliberate transfer of recombinant DNA into human subjects”.

“We have not changed the NIH language to keep up to date with new technologies,” says Claudia Mickelson, the biosafety officer at the Massachusetts Institute of Technology, who chairs the RAC. The new definition, she says, is part of an effort to make the RAC's guidelines “more accurately reflect the state of molecular biology and genetic engineering in the labs”.

A RAC working group that is developing the new definition is working from a far broader 1993 Food and Drug Administration (FDA) policy, which defines gene therapy as “the administration of genetic material in order to modify or manipulate the expression of a gene product, or to alter the biological properties of living cells”. It says that gene-transfer experiments include a variety of technologies, ranging from giving patients stem cells modified with a viral vector to using oligonucleotides to correct genetic mutations.

The FDA definition includes cloning, theoretically at least, and is part of the grounds on which the agency asserted its jurisdiction over that area last year (see Nature 391, 318; 318; 1998). But Mickelson says that the RAC has no intention of getting involved with cloning issues.

Phil Noguchi, director of the Division of Cellular and Gene Therapies at the FDA, calls the RAC's move to amend the definition “very healthy”, adding that “public discussion of these things needs to always be at the cutting edge”.