Two recent reports describe research into gene therapy for different aspects of diabetes. These reports are in the forefront of what will no doubt be ongoing and exciting research arising from the decoding of the human genome.

• Scientists have identified a gene called SHIP2 that appears to regulate insulin. Research in mice revealed that those with one normal copy of the gene were more sensitive to insulin than those with both copies of the gene. Mice without any SHIP2 showed signs of hypoglycemia and died within 3 days of birth. Tests determined that they were hypoglycemic because of hypersensitivity to insulin, not overproduction. Because SHIP2 appears to control sensitivity to insulin, mutations in the gene may play a role in the insulin resistance seen in diabetes. Researchers are investigating SHIP2 mutations in humans. Such findings make SHIP2 a potential gene therapy target for the treatment of type 2 diabetes aimed at improving the individual's insulin regulation.

• A protein that blocks the overgrowth of blood vessels in the eye is being studied as possible gene therapy for diabetic retinopathy. It is the proliferation of blood vessels in the eye that blocks the retina and leads to blindness in this condition. A recent study showed that treatment with the protein, called pigment epithelium-derived factor, or PEDF, prevented excessive new blood vessel formation in an animal model of retinopathy. It may also be used to treat macular degeneration.

As scientists identify specific genes whose absence or improper functioning are associated with specific conditions, more possibilities for gene therapy are offered - for diabetes as well as all disease. [See sidebar on Gene Therapy.]

Sources:

• Stephenson J. New insulin regulation finding. Journal of the AMA, Feb. 14, 2001.
• Angiogenesis Weekly. Protein licensed as possible gene therapy candidate to prevent blindness. via NewsRx.com and ADA.

What Is Gene Therapy? Our bodies contain trillions of cells, each with its nucleus. The nucleus contains a set of chromosomes, and each chromosome contains DNA, the genetic material that is unique for each living creature. Along the DNA lie thousands of genes, tiny proteins that tell the body how to operate. Missing or defective genes are responsible for specific diseases or medical disorders. In gene therapy, normal genes will be injected or otherwise delivered into the body to replace or cancel out the "bad" ones. The "good" genes will find their way to the right spot in the body and begin to function. Other research is seeking to find ways to "turn off" faulty genes, such as those that stimulate the growth of a cancerous tumor. The FDA is currently overseeing more than 200 clinical studies of potential gene therapy applications. Source:  FDA. Human gene therapy and the role of the Food and Drug Administration. Sept. 2000.