What are Inherited and Genetic Retinal Diseases?
Inherited or genetic diseases are diseases that result from abnormalities in our DNA. These abnormalities in the DNA may be inherited from parents or be randomly acquired. When DNA is defective, it may be unable to produce important proteins that are necessary for proper functioning, or it may produce abnormal substances that cause more harm than good.
Inherited retinal dystrophies is the term used to describe or refer to a wide variety of conditions that affect different parts of the retina due to a genetic defect. Retina Consultants of Houston specializes in diagnosing and evaluating inherited and genetic retinal diseases.
Types of Inherited and Genetic Retinal Diseases
There are several genetic defects that give rise to a wide range of retinal diseases – some of which we are only beginning to understand and others that we have not yet discovered. The following is a small list of some inherited or genetic retinal diseases.
- Macular degeneration
- Stargardt’s Disease
- Fundus Flavimaculatus
- Leber’s Congenital Amaurosis
- Doyne Honeycomb Dystrophy
- Bardet Biedl Syndrome
- Stickler Disease
- Wagner Disease
- North Carolina Macular Dystrophy
- Vitelliform Macular Dystrophy
- Best Dystrophy
- Pattern Dystrophies
- Familial Fleck Retina
- Gyrate Atrophy
- Congenital Stationary Night Blindness
- Cone Disease
- Cone-Rod disease
- Congenital Stationary Night Blindness
- Dominant Drusen
- Refsum Disease
- Batten Disease
- Retinitis Pigmentosa (several types) — This is the most common inherited retinal disorder and affects the photoreceptor (light-sensitive) cells in the retina, causing some of them to fade and eventually die.
Symptoms of Inherited and Genetic Retinal Diseases
Most inherited and genetic retinal diseases (inherited retinal dystrophies) affect the macula (macular dystrophies) and the cones found within it, resulting in gradual loss of color vision, visual acuity, and contrast sensitivity, as well as central visual field defects. In addition, other mutations that affect the retinal rods are characterized by vision issues at night and loss of peripheral vision (also called “tunnel vision”).
A complete family and medical history as well as a comprehensive dilated eye exam are important first steps in diagnosing inherited or genetic retinal diseases. However, some of these conditions may present with a normal retinal exam despite symptoms. Hence, we may conduct further testing in our office to help make a correct diagnosis.
Depending on the disease suspected, testing may include optical coherence tomography (OCT), fundus photography, fundus autofluorescence, indocyanine green angiography (ICG), fluorescein angiography (FA), visual field testing, color vision testing, dark adaptometry, and an electroretinogram (ERG), or electroculogram (EOG). You may learn more about these particular tests under our diagnostic testing section.
In addition, genetic testing has come a long way in the past several years, and many of the defective genes that give rise to inherited and genetic retinal conditions have been identified. Your Retina Consultants of Houston physician may suggest that you undergo genetic testing to correctly identify the responsible gene and possibly provide some insight into the hereditary nature of the condition. Since many of the inherited retinal diseases may also involve other areas of the body, it is important for your primary care doctor to also inquire about and investigate these other potential conditions.
Treatment and Prognosis
First and foremost, your retina specialist will make sure that you do not have an underlying disease that can be treated (examples are Refsum disease or Bassen-Kornzweig syndrome). Although most patients with diseases such as vitelliform dystrophy and flecked retina may continue to have good vision throughout life, patients with diseases like Stargardt’s or retinitis pigmentosa may develop very poor vision.
With the exception of wet macular degeneration, which has treatments that can be successful if it is caught early, the vast majority of inherited and genetic retinal diseases unfortunately have no treatment at the present time. Low vision specialists may be consulted to maximize vision potential with glasses or magnifiers.
Patients are also monitored regularly to make sure they do not develop any additional complications that may result from their retinal disease. For example, patients with Stargardt’s disease, Best’s disease, or pattern dystrophies are evaluated for choroidal neovascularization (the growth of abnormal blood vessels under the retina), and patients with retinitis pigmentosa are monitored for the development of cataracts and macular edema. These complications may be managed with injections, eye drops, or cataract surgery in the case of visually significant cataracts.
Future Developments in the Management of Inherited and Genetic Retinal Diseases
It is understandably frustrating for patients to be told that currently there is no treatment or cure for their eye disease. However, the future holds great promise in the area of inherited and genetic retinal disease. There are several trials underway utilizing gene therapy as a potential treatment for hereditary forms of retinal disease. Gene therapy essentially works by replacing or compensating for the defective DNA that caused the disease in the first place. Gene therapy trials for Leber’s congenital amaurosis (LCA) in particular have already shown some remarkable results.
Retina Consultants of Houston’s board-certified, sub-specialized retina physicians are on the forefront of research and are leaders in clinical trials. We strive to offer patients the safest, most up-to-date, and most effective therapies as they become available. Please contact us to inquire about participation in any future clinical trials on inherited and genetic retinal conditions.