A Possible Cure for Color Blindness

Color blindness is a condition often caused by a genetic disorder occurring on the X chromosome in which the pigments in certain nerve cells in the retina are not able to decipher the different wavelengths of light entering the eye. The cells in which this process takes place are called the cones. In a normal human retina, there are two different types of cells that detect light: cones and rods. Subsequently, there are three different types of cones, each containing a different pigment. When the pigments absorb light, the cone is activated and one is able to see the section of the color spectrum corresponding to the pigment in that cone. Each cone has a different spectrum of absorption and the light absorbed into the cells is determined by wavelength of the light.

In the study, the scientists used two color blind monkeys that had been trained to react with a touch screen monitor and react when various patterns were placed on the screen. When certain hues of green and red were displayed, the monkeys could not detect a difference between the green, grey, and red dots, and did not receive their grape juice.

The the monkeys in the study "lacked a gene called 'L opsin' that codes for the red-sensitive cone. The same gene defect causes most cases of red-green colour blindness in humans." Over a period of time, the scientists were able restore full vision in the monkeys "by injecting a virus modified to contain the L opsin gene into the retina."

The progress of the monkeys' vision was monitored closely over the following 24 weeks and there was significant improvement. After the 24 week period, the monkeys were readily able to distinguish between the three differently colored dots.

That being said, I find it quite interesting that it is possible to reverse a genetic disorder by injecting a virus into a person with the intent of restoring full cell functionality. This would make sense since viruses imbed their DNA into the DNA of the host cell, forever mutating it to contain the same genetic information and replicating that mutated DNA over and over again.

While people with color blindness are able to live life with relatively small inhibition due to their disability, it would be beneficial for the population affected by color blindness. Almost 1 in 10 males is affected with some sort of color blindness, but only 0.5% of females is affected. This is due to the fact that females have two XX chromosomes, while males only have one. Because of this, if there is any type of colorblind mutation on the male's X chromosome, he will have some sort of color blindness.

Hopefully, in the near future, scientists will get permission to begin using this treatment on human subjects, as the adeno-associtated virus used to inject the mutant L opsin gene into the cell has no known adverse effect on humans.

http://www.timesonline.co.uk/tol/news/science/medicine/article6837392.ece