Inherited Retinal Diseases: A Glimpse into the World of Genetic Vision Loss

Uncovering the Genetic Basis of Retinal Dystrophies

The Genetic Basis of Retinal Dystrophies

By Abigail Fahim, MD, PhD, as told to Hallie Levine

Hello, readers! Today, we’re diving deep into the world of inherited retinal diseases (IRDs). Don’t worry, we won’t lose you in a sea of scientific jargon. Instead, we’ll explore this fascinating topic in a way that will bring light to your eyes and a smile to your face.

IRDs and Your Genes: A Dance of Proteins Gone Wild

Picture your genes as tiny superheroes within your body’s spandex-clad laboratory. They contain the instructions for the proteins that make your body function smoothly. From building bones to determining eye color, these proteins do it all.

Unfortunately, sometimes these superheroes have a misstep. A gene’s DNA sequence undergoes a change, also known as a variant. And just like a clumsy superhero, this variant throws things off balance, causing a specific protein to misbehave.

When it comes to IRDs, there are over 300 genes involved. These genes have a wide repertoire – some are retina-specific, while others play a role in different parts of the body. It’s a mystery why some gene mutations solely affect the retina, while others wreak havoc in various organs. It seems the retina is a like a temperamental diva, demanding all the attention.

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Ah, yes, the most famous IRD superstar is retinitis pigmentosa. Like a fading starlet, it gradually extinguishes the light-sensing cells of the retina, starting with night vision and eventually snuffing out peripheral and central vision too. But retinitis pigmentosa is not alone. We also have Stargardt disease, which damages the macula as if it’s in competition for a leading role. And let’s not forget cone-rod dystrophy and Leber Congenital Amaurosis, the quirky supporting actors that deserve their time in the limelight.

IRDs Are Inherited: A Family Drama Packed with Genetic Tidbits

In the realm of inherited diseases, IRDs are the protagonists, and your parents are the scriptwriters. Even if you’ve grown up with no hint of these conditions in your family, your genes can still surprise you.

Now, let’s unravel the three basic inheritance patterns that determine your genetic fate:

1. Autosomal dominant: Think of this pattern as a domineering boss. If you inherit one dominant gene variant from a parent, and the other copy is unaffected, the boss gene takes center stage and, boom, you’ve got the disease. If you have the disease yourself, there’s a 50% chance of passing it on to your child. Family gatherings just got a lot more interesting.

2. Autosomal recessive: Here, we have a sneaky storyline. Each parent passes on a recessive variant gene, which can go unnoticed through generations. The parents themselves are mere carriers, as they have one normal gene and one pesky variant copy. If both parents are carriers, there’s a 25% chance their child will inherit both genes and develop the IRD. Even if they dodge the disease, there’s still a 50% chance they’ll carry it for future generations. Talk about family secrets.

3. X-Linked disorders: Here’s where gender enters the genetic stage. Some variants decide to situate themselves on the X chromosome and create pandemonium. Since women have two X chromosomes, they can carry one diseased gene and one healthy gene, like undercover agents playing both sides. But alas, men have only one X chromosome, making them more susceptible to these X-linked disorders. It’s a genetic game of chance with higher stakes for the male players. Poor fellas.

Genetic Testing: Decoding the Secrets of Your DNA

When you suspect you’ve fallen victim to an IRD, a whirlwind of clinical tests ensue. Strap yourself in for this wild ride:

• Electroretinogram (ERG): Prepare for a light show! An ERG flashes lights at your retina while electrodes measure its response. If you have an IRD, the retinal cells’ poor performance will be visible in the decreased electrical activity. It’s like watching a concert with the sound on mute.

• Visual field testing: Grab your popcorn and watch that dot of light. Your doctor will have you follow it as it dances around a half-circle directly in front of you. Whenever you spot the light, press that button, and voila! This test helps determine the extent and location of your vision loss. It’s like playing a high-stakes game of “spot the dot.”

• Genetic testing: Here comes the pièce de résistance. This test gives us the exact type of IRD you’re facing. Your doctor will collect a blood or saliva sample, send it to the lab, and let the genetic detectives do their magic. This crucial information not only guides potential treatment options, including clinical trial eligibility, but also raises awareness in your family. And hey, it might even reveal some unexpected health risks. Who knew genes could be such gossip queens?

Gene Therapy: Unleashing Superheroes to the Rescue

Cue the triumphant superhero music! Gene therapy, the treatment of choice for IRDs, may hold the key to a brighter future. Imagine sending a new gene to your body’s cells like a messenger delivering hope.

The eye, dear readers, has proven to be an ideal stage for this gene therapy spectacle. It’s like a small, exclusive theater where foreign substances are met with applause rather than rejection. Truly a rare gem in the world of medical theatrics.

To stay in the loop and participate in the unfolding drama of gene therapy, join patient data registries such as My Retina Tracker. It’s free, it’s enlightening, and it fuels the fire of hope. Though only one gene therapy has graced the stage of approved treatments, the number of trials has skyrocketed in the past decade. The future looks bright, my friends!

Now that we’ve delved into the enchanting world of IRDs and genetic mysteries, it’s time for you to be the hero. Share your thoughts and questions below, and let’s embark on this vision-saving adventure together! 🦸‍♀️🦸‍♂️