New Usher Model Bolsters Prospects for Future Treatments

Foundation-funded researchers have developed a mouse model of Usher syndrome type 2A (Usher 2A) that provides experts with better targets for treatments and a better platform for preclinical testing of potential therapies.

The mouse model, which was developed by a team led by Tiansen Li, Ph.D., Harvard Medical School, Massachusetts Eye & Ear Infirmary, closely resembles Usher 2A in humans — the most common type of Usher syndrome. It is the first Usher syndrome model in which the animal develops both vision and hearing loss. Prior
to this advancement, existing mouse models bearing defects in Usher genes showed only hearing loss.

Li and his colleagues developed the model by disrupting — or “knocking out” — both copies of the animal’s USH2A gene.

The normal USH2A gene leads to the production of proteins which are necessary for cilia — tiny hair-like structures — to function properly in the retina’s photoreceptors and the cochlea of the inner ear. The inability of these cilia to function well leads to hearing and vision loss.

Li says that this mouse model opens the door for the development of gene replacement therapy to treat Usher 2A, and it can also be used for the evaluation of other potential therapies for Usher 2A as well as other types of Usher syndrome.

A research paper on Li’s USH2A model development was published in the March 5, 2007 issue of the Proceedings of the National Academy of Sciences.