Another aspect of gene therapy is gene silencing,
also called antisense technology. With this method,
geneticists can inactivate a gene that may cause
disease or be defective.
When DNA replicates, RNA bonds to half of the split
double helix, making a mold of sorts. The RNA (messenger
RNA or mRNA) is then used to create an identical
DNA strand. To silence a gene on a chromosome, scientists,
therefore, simply make an RNA strand 15-20 bases
in length complementary to the mRNA. The synthesized
RNA will attach itself to the mRNA and prevent that
portion of the mRNA from creating the gene on the
duplicate DNA strand. This method is highly specific.
Gene silencing is used to treat several viruses
including AIDS, Herpes, Chicken Pox, and Hepatitis.
More importantly, though, antisense technology is
used by geneticists in research to learn what happens
when certain genes are silenced.