One of the most exciting developments in gene therapy is a gene editing method called CRISPR-Cas9 that can remove, alter or add sections of the DNA sequence.
A group of scientists led by the University of Iowa have been using CRISPR-Cas9 on mice to disrupt a mutant gene that causes certain forms of glaucoma. Glaucoma is one of the leading causes of irreversible blindness. Elevated intraocular pressure (inner eye pressure) creates stress on the optic nerve. If the optic nerve is damaged, permanent vision loss can occur. Currently, there is no cure for glaucoma, and it affects 2 percent of people over the age of 40.
Glaucoma is a broad term that refers to an entire family of diseases, so it is impossible to isolate a single cause of the disease. Certain types of glaucoma are caused by alterations to a protein called myocilin. This protein is found in the trabecular meshwork, a part of the eye that regulates eye pressure. A mutation in the myocilin gene can cause the production of a mutant protein associated with elevated inner eye pressure in juvenile and adult-onset primary open-angle glaucoma.
The team discovered that using CRISPR-Cas9 to edit and disrupt the mutant myocilin gene halted the production of the mutant protein, which prevented spikes in intraocular pressure in the eyes of mice. Applying gene therapy to correct the myocilin mutation prevented the development of glaucoma.
Although CRISPR-Cas9 is mostly used in animal models, scientists hope this gene replacement method could be routinely used in humans to treat disease. The University of Iowa team later used the same CRISPR-Cas9 editing technology to disrupt mutant myocilin genes in cultured human eyes. More research needs to be done before human trials begin. However, the researchers hope that this new method could treat glaucoma associated with defective myocilin in humans (Source: Science Daily).