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Archive - Sep 18, 2009

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Gene Therapy Cures Color Blindness in Monkeys--Wider Applications Seen

Researchers have successfully used gene therapy to cure red-green color blindness in adult squirrel monkeys. Red-green color blindness is the most common single locus genetic disorder in humans. One in 12 men and 1 in 230 women are affected, while 1 in 6 women is a carrier of the inherited condition. “We’ve added red sensitivity to cone cells in animals that are born with a condition that is exactly like human color blindness," said Dr. William W. Hauswirth, an author of the study. “Although color blindness is only moderately life-altering, we’ve shown we can cure a cone disease in a primate, and that it can be done very safely. That’s extremely encouraging for the development of therapies for human cone diseases that really are blinding.” “People who are colorblind feel that they are missing out,” said Dr. Jay Neitz, one of the senior authors of the study. “If we could find a way to do this with complete safety in human eyes, as we did with monkeys, I think there would be a lot of people who would want it. Beyond that, we hope this technology will be useful in correcting lots of different vision disorders.” In this work, the researchers wanted to produce a substance called long-wavelength opsin in the retinas of the monkeys. This particular form of opsin is a colorless protein that works in the retina to make pigments that are sensitive to red and green. “We used human DNAs, so we won’t have to switch to human genes as we move toward clinical treatments,” said Dr. Hauswirth, who is also involved in a clinical trial with human patients to test gene therapy for the treatment of Leber congenital amaurosis, a form of blindness that strikes children. Of further note is the fact that approximately 1 in 30,000 Americans has a hereditary disease called achromatopsia, which causes nearly complete color blindness and extremely poor central vision.

SNP Variant Associated with Clearance of Hepatitis C Virus

An international research team has shown that a particular SNP genotype (C/C) near the IL28B gene appears to be associated with the ability of some people to defeat hepatitis C virus (HCV) infection and get rid of the virus with no treatment. HCV infection is the most common blood-borne infection in the United States, with estimates of 4 million HCV-infected individuals in the United States and 170 million worldwide. More than seventy percent of people who contract hepatitis C will live with the virus that causes it for the rest of their lives and some will develop serious liver disease including cancer. However, 30 to 40 percent of those infected somehow defeat the infection with no treatment. Previous work had shown that individuals with the C/C SNP genotype near IL28B were more likely to respond to treatment for hepatitis C, which can rid some patients of the virus. So, in the current work, the researchers investigated if the C/C variation—as opposed to the C/T or T/T alternatives—also played a role in some peoples' ability to get rid of the virus without the help of medication. To do this, the scientists assembled information from six different studies that had, over many years, collected DNA and hepatitis C infection information from people all over the world. The team then analyzed DNA in the IL28B gene vicinity from a total of 1008 patients: 620 persistently infected and 388 who had been infected but no longer carried any virus. DNA analysis revealed that of the 388 patients who no longer carried virus, 264 had the C/C variation. "This is the strongest clue to date to understanding what would constitute a successful immune response," said Dr. David Thomas, lead author of the article.