Scheie Eye Institute, University of Pennsylvania
There are several hereditary vision diseases that affect the macula, the central part of the retina that is responsible for providing sharp, clear, straight-ahead vision. One of them, called Best’s disease, is also known as vitelliform macular dystrophy.
Best’s disease usually develops in the first decade of life, but may not cause symptoms until later. Symptoms are blurry, distorted, or missing central vision. It can be diagnosed by a dilated eye exam with an ophthalmoscope. In this disease, the macula typically looks like a “sunny side up egg,” which can later burst, releasing fluid into the macula and causing macular degeneration. Additional helpful tests are optical coherence tomography (OCT), a type of noninvasive retinal imaging technique that generates a cross-section picture of the retina in a few seconds, and the electro-oculogram (EOG), which measures the electrical potential across the retina.
The gene responsible for Best’s disease is called bestrophin, or vitelliform macular dystrophy 2 (VMD2). Usually, mutations are dominant, so that the children of an affected parent have a 50 percent chance of getting the disease. The normal function of bestrophin is to conduct ions, like calcium and chloride, across the membrane of a cell type in the back of the retina, called the retinal pigment epithelium.
Researchers are trying to develop gene and other therapies based on this knowledge, but currently there are no specific treatments for this disease.
There has been significant progress in research efforts to develop a gene therapy treatment for Best’s disease. Gene therapy for retinal diseases is now considered a viable approach, as the FDA recently approved retinal gene therapy for an inherited form of blindness called Leber’s congenital amaurosis. The same technical approach, using a non-disease-causing virus called adeno-associated virus (AAV) should now be translatable to additional retinal diseases.
Proof of principle that AAV gene therapy will work for Best’s disease is provided by the treatment of dogs with Best’s disease in an article published recently by investigators from the University of Pennsylvania (UPenn) and the University of Florida (UF).
A company called Ophthotech has a licensing agreement with the University of Pennsylvania to develop these findings into a treatment for patients. They hope to begin clinical trials in 2021. Also, once a clinical trial begins, information on the trial can be found at our Antidote clinical trial search tool or on clinicaltrials.gov.
With more research and clinical trials, the future is bright for Best’s disease.
Joshua Dunaief, MD, received his BA magna cum laude in Biology from Harvard (1987), MD/PhD from Columbia College of Physicians and Surgeons (1996), completed ophthalmology residency at the Wilmer Eye Institute, Johns Hopkins in 2000, and medical retina fellowship at Scheie Eye Institute, University of Pennsylvania in 2004.
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