Spectacular results in three patients with hereditary retinopathy after application to both eyes.
Three patients with congenital Leber's amaurosis found their light thanks to gene therapy
Washington, DC
Three US patients who lost their light in childhood showed significant improvement in their vision after undergoing gene therapy in both eyes.
Dramatic improvement
These patients suffering from a rare inherited eye disease, congenital Leber's amaurosis, had already shown relative improvement in their vision after undergoing gene therapy in one eye. Now the repair of the genetic defect in the second eye has led to spectacular results.
It is characteristic that one of the patients, the Tammy Morehouse, described to the British news agency BBC how, after the gene therapy was applied to her second eye, she was able to see her children's faces for the first time. She said Ms. Morehouse may not be able to see well enough to read or drive but she can enjoy her loved ones and look at the light as it passes and disappears over Lake Erie, located in the area where she lives. «To a person who previously could not see at all, to gain even one degree of vision is precious» the patient noted.
Leber's congenital amaurosis is caused by defects in a gene that codes for a protein that is crucial for vision. The condition occurs soon after birth or within the first few months of life, leading to severe vision problems, involuntary eye movements and very «poor» night vision. The disorder does not allow the normal function of the retina of the eye to be substantially impaired.
The first results
The researchers, led by experts from the University of Pennsylvania's Neuroscience Institute, had already revealed in 2008 that the application of gene therapy to 12 people with the disease had led to a partial recovery of vision. In particular, these results had been obtained after injecting into one eye of the patients a modified virus carrying the healthy RPE65 gene which in this group of sufferers is defective.
Now the same team in a new publication in the journal «Science Translational Medicine» reports that they have now applied the treatment to the second eye of three patients in the original group. As it turned out, there was an even greater improvement in their vision.
The three volunteers could see better in the half-light and two of them were even able to avoid obstacles.
Significant benefits of dual application
As the study leader Dr. Gene Bennett these patients are now able to do things that were impossible for them before, such as walking at night, shopping for essentials and recognising faces. The expert noted to the BBC: «We have shown that it is possible to safely treat both eyes of patients with this form of retinopathy using genetic therapy and we have shown that the brain perceives the visual signals received by the retina.».
Indeed, MRI scans performed on the patients showed that the brain was able to «see» the patients' new eyes.
The brain «sees» the... new eyes
According to Dr. Manjar Astari from the Philadelphia Children's Hospital that performed the MRIs «imaging tests showed that the brain is activated after treatment and responds to visual stimuli».
The researchers now plan to move on to apply the treatment to the second eye of the remaining nine patients in the initial group and then expand their clinical trial. Dr Bennett stressed that «I believe these results will lead to the treatment of more common forms of blindness in both eyes.».
