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How Genetic Counseling Affected One Patient with Retinal Disease

It is my strongly held belief that access to appropriate genetic testing and genetic counseling should be available to everyone regardless of location, race, culture, or socio-economic status. Our work here at InformedDNA provides these nation-wide services on not only a clinical but also a research basis. I have the privilege of providing genetic counseling to individuals with inherited retinal disorders as part of a research study via telemedicine or by telephone, in the privacy of their own homes, and at no cost to the patient.

A Profound Experience
As a child, Mary* had difficulty seeing in the dark. She couldn’t keep up with her neighborhood friends when playing tag at night and was anxious at sleepovers. In her teenage years she started having difficulty with her peripheral vision; she would trip on stairs, lose her footing when hiking, and miss her friends waving across the lunch room. It wasn’t until the age of 31 that Mary received a diagnosis that explained her vision problems and clumsiness. When she found out she had retinitis pigmentosa, she was “in shock” to learn that she had a genetic eye problem, even though none of her relatives wore glasses.

Retinitis pigmentosa (RP) causes progressive vision loss due to abnormalities of the retina, the layer of light-sensitive tissue at the back of the eye. In typical RP, individuals first experience difficulty seeing at night, progressing to total “night blindness.” Loss of night vision is typically followed by loss of peripheral (side) vision. For some individuals with RP, loss of central vision occurs late in the course of the disease, while other individuals retain a very small area of good central vision throughout their lives. Most individuals with RP will be declared legally blind in adulthood.

RP affects approximately one in 4,000 individuals in the United States and there is no known cure. In the past several years, there have been great strides towards developing treatments for this rare disorder, and in late 2017 the FDA approved the first ever gene (augmentation) therapy for one rare sub-type of childhood onset retinal disease. The tricky thing with gene therapy is that it needs to be gene-specific and there are more than 100 genes known to cause RP.

Over thirty years have passed since Mary first heard the words “retinitis pigmentosa.” She has grown to accept her diagnosis and visual limitations, but it has been a challenge. At first, learning how to use a white cane was a significant psychological barrier, with the shame of showing her “disability” to everyone who sees her with her cane. She’s worked with a psychologist, completed training at a low vision center, worked with a low vision specialist in her home, and even attended a women’s low vision camp. Earlier this year, Mary completed training for and received her first seeing eye dog. To say the two have hit if off is an understatement. She told me that “she [my dog] has given me back my life” and boasted of increased daily activity and more confidence walking outside of the home.

Historically, access to genetic testing and genetic counseling were limited due to insurance non-coverage, prohibitive out of pocket costs, and lack of widespread knowledge about result interpretation. Even though Mary has been seen by multiple retinal specialists, participated in a clinical research study, and asked questions about the risks to her family members for years, she has never undergone genetic testing.

I met Mary in my professional role as a genetic counselor for InformedDNA. Currently, patients who participate in the MyRetinaTracker (see below) Genetic Testing Initiative receive their test results in a detailed one-on-one discussion with a genetic counselor that includes information about what the results might mean for the patient as well as their family members.

As I prepared for Mary’s appointment, I knew I had some important news to convery: the test results had come back positive. Testing revealed that the patient was compound heterozygous for a pathogenic variant and a likely pathogenic variant in the PDE6B gene. If you’re scratching your head reading that last sentence, you are not alone. That’s why it’s the job of a genetic counselor to turn that “lab-speak” into something meaningful for their patients.

We all have two copies of each of our genes: one inherited from our mother and the other inherited from our father. These genes provide genetic instructions for how our bodies should grow, develop, and maintain health over time. Specifically, the PDE6B genetic instructions are important in maintaining the health of the retina. When the PDE6B genetic instructions are incorrect, however, an individual will develop significant night vision loss in early childhood and will develop RP over his/her lifetime. When the genetic instructions are incorrect, we use the word “mutation” or “pathogenic variant” to describe a change in the sequence or spelling of the genetic instructions that causes disease.

Mary was found to have two of these mutations in the PDE6B gene, presumably one inherited from each parent. Her parents are each what we call a “carrier” of RP; in addition to one mutation, each of them also has a normal copy of the gene, so they don’t have any related vision problems. When two carriers have a child together there is a one in four (25%) chance that they would both pass on their mutation and, therefore, that their child would have two mutations (with no normal copy of the gene) and would go on to develop RP. This pattern of inheritance is referred to as autosomal recessive.

The chances that an individual in the general population is a carrier of a PDE6B mutation is only around one in 150, so the chances of two carriers finding each other and starting a family together are quite low. (We’re all likely carriers for several genetic disorders, but most of us never know which genetic mutations we carry unless there is a family member who has been affected with a genetic disorder.) This is part of what makes Mary’s genetic test results particularly important for her family members. Mary now knows that unless her husband is a carrier of a PDE6B mutation, there would be almost no chance that her children will be affected with RP.

As Mary’s children are now of reproductive age and planning families of their own, they are able to determine which PDE6B mutation they inherited from their mother. If desired, his/her reproductive partner can also have genetic testing to see if he/she are a carrier (resulting in a 25% chance of having a child with RP) or if they aren’t a carrier (resulting in almost no chance of having a child with RP). Imagine what it would feel like to be affected with a genetic disorder and learn that your children and grandchildren are almost certain to escape that disease. Relief, validation, and a type of closure brought tears to Mary’s eyes during our consultation. She said, “It feels good to have an explanation, it feels like I can kind of move on in a way.”

While this information can be deeply meaningful, it is only one step on a long journey. As of right now, there is no treatment or cure for Mary’s PDE6B-related retinitis pigmentosa. Mary is excited about the future and feels that she has the tools she needs to stay abreast of ongoing research. I was touched when she said it’s also rewarding for her to participate in this research study for the sake of others in the retinal disorder community and future generations. Some time later, I received a message from Mary that hit home the importance of genetic testing and genetic counseling: “Thank you so much for your time and making this information very understandable and relevant for me. It was very profound and I’m still feeling a wave of emotion.”

My Retina Tracker
Mary participated in a research study sponsored by the Foundation Fighting Blindness (FFB) that provides genetic counseling and genetic testing free of charge for participants in My Retina Tracker, the FFB registry for people who have received a clinical diagnosis of an inherited retinal degenerative disease (IRD). The goals of the study are to determine the prevalence of genetic mutations associated with these diseases and determine if removing the barrier of cost improves patient and clinician participation in genetic testing.

My Retina Tracker can also be used by researchers looking to accelerate enrollment in clinical trials. When researchers have to contact retinal specialists throughout the country and ask them to review their records to see if they can find one or two patients with a mutation in a particular gene, recruitment can (and often does) take a very long time. But if a researcher can query a de-identified database to determine how many individuals have mutations in that gene, and pass along information to those individuals specifically, the hope is that the clinical trial will reach enrollment much more quickly, speeding up the time needed to go from an initial clinical trial to an FDA-approved therapy.

After nearly two years of working with this rare disease population as part of the My Retina Tracker Genetic Testing study, I feel we are driving research forward. I can’t promise that every test result will identify disease-causing mutations or that every single gene will eventually be matched with a treatment or cure. But, I’m proud to say that we’re making progress by getting each patient’s foot in the door with a confirmed genetic diagnosis.

*Names have been changed to protect the patient’s identity.

InformedDNA is the authority on the appropriate use of genetic tests. We employ the largest and most experienced full-time staff of lab-independent genetics specialists in the nation. To learn more about our genetic counseling services, our Genetics Services Program™ solutions for health systems and hospitals, or our Genetic Benefits Management™ services for health plans, please give us a call at 800-975-4819; send an email to info@informeddna.com; or, just fill out the form below and we’ll get in touch shortly.