Gene processing is progressing faster than most of us can match. An important announcement recently was the application of the gene editing tool CRISPR to non-genetic diseases thanks to the new ability to edit individual letters in RNA.
Although CRISPR achieves milestones like these, scientists are finding new uses for the treatment of genetic disorders. The next treatment that will come to the clinics is a CRISPR treatment for a form of blindness called Liver Congenital Amaurosis (LCA).
Following approval by the FDA in December, treatment will be the first of its kind to be tested in the EU.
What is Life Cycle Assessment?
Life Cycle Assessment is a group of hereditary diseases that cause severe vision loss at birth. Both parents must have a defective gene for the disease so that a child can inherit it. 2 to 3 out of 1
The cause may be mutations in at least 14 different genes that play a role in the development of the retina (the nerve cell layer on the back of the LCA), an eye that senses light and sends signals to the brain. This applies to both peripheral rod cells, which support low-light vision, and central cone cells, which are critical to seeing detail and color.
Students with LCA Attract Not normally respond to light, do not expand or contract, depending on how much light enters the eye. For example, in one version of the disease, a mutation in the gene responsible for the metabolism of vitamin A reduces the ability of photoreceptors (specialized neurons in the retina) to send visual information to the brain and leads to early death of photoreceptor cells.  How CRISPR Would Repair It
In CRISPR gene editing, scientists bind a synthesized sequence of leader RNA that matches the target DNA sequence to the enzyme Cas-9 and introduce it into the nucleus. When the appropriate DNA sequence has been found, Cas-9 cuts the DNA strand and the cell repairs the cut.
The mutations most responsible for LCA occur in the genes CEP290, CRB1, GUCY2D and RPE65. In LCA type 10, a mutation in CEP290 leads to a dysfunction of a protein that promotes the assembly of photoreceptor cells in the retina.
After a portion of the gel-like tissue in the eyes has been removed, the patient is injected with the treatment behind the retina. The hope is that the patient's DNA will repair itself in a manner that restores normal protein function, eventually fixes and displays its photoreceptor cells.
Treatment is conducted by Editas Medicine of Cambridge and its Dublin-based pharmaceutical partner Allergan.
Although this is the first study in which CRISPR is used to edit DNA in the human body, CRISPR-based medicine was not first tested in humans. Treatment of LCA was a form of gene therapy applied.
CRISPR was used in the US for the first time this year to treat patients when physicians at the University of Pennsylvania combined it with cancer treatment CAR-T to treat two patients (the results of the treatment have not yet been published).
In late 2017, the FDA approved a gene therapy called Luxturna for the treatment of LCA2, a form of the disease that is caused by a mutation in a different gene. This was the first direct gene therapy for a hereditary disease approved in the US has been. Only one other company, Sangamo Therapeutics, has attempted to process genes in the body to treat metabolic diseases with a tool called a zinc finger.
The difference between the LCA2 treatment and the treatment of LCA10 patients is that Luxturna inserts a healthy copy of the defective gene directly into the retinal cells, whereas CRISPR localizes the defective gene on the DNA strand cuts the right spot and makes it self-repairable.
However, the CRISPR treatment for LCA can not be guaranteed to work, it holds promise; Luxturna successfully improved the eyesight of its recipients without any known side effects, and a similar study in the Netherlands led to an improvement in vision in about 60 percent of the participants.
The treatment is scheduled to begin this fall in 18 children and adults and last until 3 years.
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