Tag Archive cone rod dystrophy

Cone-Rod Dystrophy Gene Therapy Rescues Vision in Canines

Cone-Rod Dystrophy Gene Therapy Rescues Vision in Canines

Originally posted at blindness.org

October 10, 2013

A French research team led by Fabienne Rolling, Ph.D., of INSERM, has used gene therapy to restore vision in a canine model of cone-rod dystrophy caused by mutations in the gene RPGRIP1. Reported in the journal Molecular Therapy, the advancement marks the first time RPGRIP1 gene therapy has been used successfully in a large-animal model of cone-rod dystrophy. Demonstration of safety and efficacy in a large animal is an important step in moving the therapy into human studies. Dr. Rolling says that her team is now adapting the RPGRIP1 for evaluation in humans.

In humans and the canine model, cone-rod dystrophy affects cones first, leading to loss of visual acuity and color vision in childhood. Loss of peripheral and night vision follow as the disease progresses and affects rods.

In the RPGRIP1 gene therapy study, cone function was significantly rescued in the canines while rod function was preserved. The therapy’s effect on vision persisted for 24 months — the length of time vision was monitored by the INSERM team.

Certain mutations in RPGRIP1 can also cause Leber congenital amaurosis (LCA), a severe form of retinitis pigmentosa that affects young children. Dr. Rolling says that her team’s gene therapy will target LCA caused by RPGRIP1 mutations.

A Foundation-funded research group from Massachusetts Eye and Ear Infirmary (MEEI) is also developing a gene therapy for LCA caused by mutations in RPGRIP1. Their lab studies are ongoing as they move toward launching a clinical trial.

“We are very pleased with the RPGRIP1 gene therapy efforts at INSERM and Mass Eye and Ear,” says Stephen Rose, Ph.D., chief research officer, Foundation Fighting Blindness. “As these two teams report results, they will learn from each other. Ultimately, that will help lead to an optimal therapy for the patients.”

Both the MEEI and INSERM treatments involve delivery of healthy copies of the RPGRIP1 gene to replace defective copies. The researchers insert the healthy copies into a specially designed virus which penetrates rods and cones to deliver the therapeutic genetic cargo. The virus is contained in a drop of liquid injected underneath or near the retina. Studies have shown that a single administration of gene therapy can last several years, perhaps a lifetime.

The virus used for the studies is known as an adeno-associated virus, or AAV. It is similar to the AAV being used in landmark clinical trials of LCA (RPE65 mutations) gene therapy at the Children’s Hospital of Philadelphia, the Universities of Pennsylvania and Florida and other research centers. The AAV is widely used because it penetrates cells of the retina well and has a good safety profile in humans.


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Researchers Developing Innovative Gene Therapy for Cone-Rod Dystrophy

Published first at blindness.org




April 17, 2014 – At first blush, completely shutting down both copies of a gene might not seem like the best way to treat an inherited retinal disease. That’s because genes and the proteins they express are thought to be essential to the health and well-being of all cells in the body.

But the approach was used successfully in a Foundation-funded gene-therapy study of mice with autosomal dominant cone-rod dystrophy (adCORD) caused by mutations in the gene GUCA1A, also known as GCAP1. It is one of 10 genes that can cause adCORD, a retinal degenerative disease characterized by reduced visual acuity and color perception, as well as loss of central and daytime vision. Affected individuals are often legally blind by the age of 40.

Led by Wolfgang Baehr, Ph.D., and Li Jiang, Ph.D., at the University of Utah, the study provided a proof-of-concept for an approach they hope to use in humans. Results were published in Frontiers in Molecular Science.

The scientists shut down the normal and the mutated copy of GCAP1, because the approach was simpler than trying to target only the defective copy, and the investigators determined that vision wasn’t compromised when the healthy copy was also shut down.

GCAP1 is a gene that leads to the production of a protein involved in phototransduction, the biochemical process in photoreceptors that converts light to electrical signals, which are sent back to the brain and interpreted as vision. However, if one of the two GCAP1 copies is defective, a toxic protein is produced and adCORD develops.

To be effective in most cases, a gene therapy for an autosomal dominant retinal disease must either shut down the defective gene copy and leave the normal copy intact, or deliver a copy of the normal gene after shutting done both copies. In some cases, scientists can override the defective copy by only delivering a normal copy.

However, Dr. Baehr’s team found that in the case of GCAP1, shutting down both copies successfully halted retinal degeneration in mice; even with no normal copy, the phototransduction process worked well and vision was preserved.

Dr. Baehr believes that the protein expressed by GCAP1 is not essential for normal vision or retinal health. However, the defective protein is toxic.

To shut down the GCAP1, Dr. Baehr developed a gene therapy which produces messages known as short-hairpin RNA (shRNA). The shRNA block GCAP1’s naturally occurring RNA messaging system, rendering the gene inactive.

“What is most impressive about this gene therapy approach is its simplicity,” says Stephen Rose, Ph.D., chief research officer of the Foundation Fighting Blindness. “The strategy of shutting down the gene altogether will not work for a vast majority of other retinal degenerations, but for GCAP1, it is the most straightforward therapeutic path, so it makes sense to take it.”

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Cone Rod Dystrohpy: What it is, and can you help?

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Information on diet, nutrition & self-help options

Rod cone dystrophy is expressed as a number of inherited eye problems, due to the common cause of malfunctioning of the cone and rod photoreceptors. These photoreceptors change light into electric nerve messages that transfer to our brain via our optic nerve. Cones are the photoreceptor cells which allow us to see fine details and color and comprise our central vision. Rods are for low light vision and permit night and peripheral vision. The malfunctioning photoreceptor cells be problematic starting in childhood, or may lose their functionality with time.

Self Help

Since we consider most eye conditions to be a reflection of the health of the whole body, lifestyle choices and diet can play a major factor in getting and maintaining good vision. Below are some recommendations:

Supplementation with research-proven nutrients and eyedrops that have been found to be helpful to protect vision.
See our recommendations for healthy eyes for details.
Eye exercises can help to bring energy and blood to the eyes, thereby helping to drain away toxins or congestion to the eyes. These are free general eye exercises and acupressure points for overall eye health.
It is possible to slow down vision loss and possibly maintain healthy vision:

Energy moving modalities such as acupuncture and microcurrent stimulation may be helpful.
See all retinal support vitamins & supplements
Rod and cone photoreceptors are good at seeing different things. Here are some examples:

Rods are good at ‘seeing’:

things that move but only in black and white
seeing in the dark
seeing things on the sides of us (peripheral vision)
Cones are good at ‘seeing’:

things that are still
fine details of thing in daylight
objects in color
things in fine detail including reading, looking at photographs and recognizing faces

gradual loss of night vision
gradual loss of peripheral vision
sensitivity to bright light
vision is best at dusk
errors in color vision in both red-green and blue-yellow ranges
Young children with Rod-Cone Dystrophy may develop:

Fast ‘to and fro’ movements of the eyes. This is referred to Nystagmus.
‘Roving’ eye movements where the eyes appear to slowly wander around not fixing and staying still on any objects.
‘Eye Poking’ where the child touches their eyes with their fingers.
Parents will often notice these signs by the way the child acts.


There are many different causes of Rod-Cone Dystrophies. Often one does not know why a child has a Rod-Cone Dystrophy. When no cause can be identified this is called Idiopathic.

Most Rod-Cone Dystrophies are genetically based and result from “misprints” in a child’s genes, and are typically carried forward from the parents’ genes although sometimes by chance a new mistake occurs in the child’s genes and the parents’ genes are normal.

Conventional Treatment

There is no good conventional way to stop the sight loss in Rod-Cone Dystrophy.

Related Conditions

Other eye conditions where the rod and cone photoreceptor cells do not work properly include: Leber’s Amaurosis, Retinitis Pigmentosa, Usher’s Syndrome and Batten’s Disease.

Synonyms: Retinal Cone Degeneration, Retinal Cone-Rod Dystrophy, Cone Rod Dystrophy, Combined Cone-Rod Degeneration, Cone Rod Degeneration, Progressive Cone Rod Dystrophy, Retinal Cone Dystrophy, Retinal Cone Rod Dystrophy


Though there are no specific studies on nutrients and this particular condition, there is extensive research on nutrients such as lutein, zeaxanthin and bilberry among others that have been shown to be essential for the health of the rod-cone structures. Based on these studies, Dr. Grossman has selected specific nutrients and products to help support this part of the eye and overall eye health. Some research on macular degenerationor retinitis pigmentosa may be applicable.
Thank you naturaleyecare.com


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