Nav: Home

Genetic discovery linked to rare eye disease, MacTel

September 11, 2019

SALT LAKE CITY, September 11, 2019--John A. Moran Eye Center physician-researcher Paul S. Bernstein, MD, PhD, and his patients at the University of Utah played a key role in the recent discovery of the first genetic cause for a rare eye disease.

Macular telangiectasia type 2 (MacTel) affects about one in 5,000 people, causing a gradual loss of central vision, typically after age 40. As part of an international research effort directed by the Lowy Medical Research Institute (LMRI), Bernstein has spent 15 years working with MacTel patients, sifting through family genetic histories.

Among 250 patients enrolled in the Utah Center for MacTel Genetics, part of an LMRI network of more than 30 centers around the world, a Utah father and son gave Bernstein and LMRI researchers a breakthrough clue. Both had MacTel, along with a rare neurological condition called hereditary sensory neuropathy type 1 (HSAN1). HSAN1 damages the peripheral nerves, typically producing tingling, weakness, and a reduced ability to feel pain and sense hot and cold in the legs and feet. Some patients do not lose sensation but instead feel shooting pains.

Research published in The New England Journal of Medicine (NEJM) on September 11, 2019, "Serine and Lipid Metabolism in Macular Disease and Peripheral Neuropathy," confirms two of the genetic variants that cause HSAN1 also cause MacTel.

"We believe this will be the first of many genes linked to MacTel," said Bernstein, one of three senior authors on the NEJM paper and a retinal specialist who directs clinical research at Moran. "This discovery gives patients hope for new treatments, and our research has important implications for other retinal eye diseases."

HSAN1 is associated with rare coding mutations in SPT genes that lead to accumulation of toxic biomolecules in the body called deoxysphingolipids (deoxySLs). Presumably, these same toxic molecules cause damage to the macula, or center of the retina, in patients with HSAN1 and MacTel.

Working with LMRI and the Deater Foundation, a Pennsylvania-based non-profit dedicated to HSAN1 research, Bernstein and fellow clinicians on LMRI's MacTel Project conducted comprehensive eye exams on a group of 10 HSAN1 patients unrelated to the Utah family. They found the majority (7/10) of the patients had MacTel.

All HSAN1 patients who did not have clinical signs of MacTel were less than 46 years old and may have been too young to exhibit signs of this late-onset eye disease. Bernstein was able to examine several of these young HSAN1 patients who did not yet show definite signs of MacTel using fluorescence lifetime imaging ophthalmoscopy (FLIO)--an extremely sensitive, non-invasive imaging technology available in the U.S. only at the Moran Eye Center. FLIO images show a characteristic crescent or ring in the macula in all patients affected by MacTel. All of the young asymptomatic HSAN1 patients exhibited the "MacTel signature" in their FLIO images, suggesting that they are at high risk of developing MacTel in the future.

Further research, combining clinical and laboratory studies, showed that many other MacTel patients also had elevated deoxySL levels, presumably due to other genetic defects or low levels of serine, an amino acid that we make and consume in our diets. Elevated levels of deoxySL in the retina were shown to compromise visual function. Low serine and the deoxySLs were not previously known to affect the eye's macular health.

Laboratory experiments determined fenofibrate, a lipid-lowering medication used for high cholesterol, shows potential for protecting the retina from deoxySLs. Areas of future research include determining how widespread the role of deoxySLs is in causing eye disease; finding the pathways that lead to elevated deoxySLs in MacTel; and developing treatment plans based on a patient's unique genetic and metabolomic profile.

These findings offer potential new insights into other more common eye and systemic diseases, like diabetic retinopathy, liver disease, and metabolic syndrome that are also associated with elevated deoxySLs.

Moran study participant Tami Murphy, a Deater Foundation executive and board member with HSAN1 and possible early signs of MacTel, said she's grateful for the many collaborators who have worked so hard over the years.

"It's exciting to be a part of an international research community that is working so hard to shed light on rare diseases, advancing our knowledge of MacTel and HSAN1," she said.
Lydia Sauer, MD, a research associate in the Bernstein Lab who specializes in FLIO, and Barbara J. Hart, clinical research coordinator at Moran, were among the more than 30 NEJM paper authors representing 14 institutions in the U.S., U.K., and Australia.

About the John A. Moran Eye Center at the University of Utah

The John A. Moran Eye Center at the University of Utah serves as the largest ophthalmology clinical care and research facility in the Mountain West with more than 60 faculty members and 10 satellite clinics. Physicians provide comprehensive care in nearly all ophthalmic subspecialties, making the Moran Eye Center a major referral center for complex cases with over 145,000 patient visits and about 7,000 surgeries annually. Moran supports 14 laboratories to develop the treatments of tomorrow. Faculty also train 12 residents, four interns, and up to 13 fellows a year in one of the nation's most selective and highly-regarded academic programs. U.S. News & World Report consistently ranks Moran among its Best Hospitals for Ophthalmology, while Ophthalmology Times surveys evaluating residency programs, clinical care, and research have ranked Moran in the nation's top 10 for having the best overall program. CEO Randall J Olson, MD, leads more than 500 employees working to achieve Moran's vision that no person with a blinding condition, eye disease, or visual impairment should be without hope, understanding, and treatment.

University of Utah Health

Related Retina Articles:

Retina-inspired carbon nitride-based photonic synapses for selective detection of UV light
Researchers at Seoul National University and Inha University in South Korea developed photo-sensitive artificial nerves that emulated functions of a retina by using 2-dimensional carbon nitride (C3N4) nanodot materials.
Delivering large genes to the retina is problematic
A new study has shown that a commonly used vector for large gene transfer can success-fully deliver genes to retinal cells in the laboratory, but when injected subretinally into rats it provokes a robust and acute inflammatory response.
Researchers have identified areas of the retina that change in mild Alzheimer's disease
Finding biomarkers that enable early detection of Alzheimer's disease is one of medicine's biggest challenges, and the retina is one of the most promising candidates.
The birth of vision, from the retina to the brain
How do neurons differentiate to become individual components of the visual system?
Retina-on-a-chip provides powerful tool for studying eye disease
The development of a retina-on-a-chip, which combines living human cells with an artificial tissue-like system, has been described today in the open-access journal eLife.
Australian researchers reveal new insights into retina's genetic code
Australian scientists have led the development of the world's most detailed gene map of the human retina, providing new insights which will help future research to prevent and treat blindness.
Shedding light on rhodopsin dynamics in the retina
Photoreceptor cells in our eyes can adjust to both weak and strong light levels, but we still don't know exactly how they do it.
Researchers uncover mechanism blocking retina regeneration
A discovery opens the possibility of one day restoring loss of vision by activating the retina's ability to regenerate.
WVU researcher explores what tumor cells and a healthy retina have in common
West Virginia University researcher Jianhai Du is parsing how the retina hijacks an energy-producing chemical reaction to churn out molecular building blocks to renew photoreceptor membranes that keep our vision sharp.
Antibodies to a retina protein to be used as a kidney cancer marker
Sechenov University together with their German colleagues suggest a new highly sensitive, quick, and pain-free method for diagnosing kidney cancer.
More Retina News and Retina Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Biology Of Sex
Original broadcast date: May 8, 2020. Many of us were taught biological sex is a question of female or male, XX or XY ... but it's far more complicated. This hour, TED speakers explore what determines our sex. Guests on the show include artist Emily Quinn, journalist Molly Webster, neuroscientist Lisa Mosconi, and structural biologist Karissa Sanbonmatsu.
Now Playing: Science for the People

#569 Facing Fear
What do you fear? I mean really fear? Well, ok, maybe right now that's tough. We're living in a new age and definition of fear. But what do we do about it? Eva Holland has faced her fears, including trauma and phobia. She lived to tell the tale and write a book: "Nerve: Adventures in the Science of Fear".
Now Playing: Radiolab

The Wubi Effect
When we think of China today, we think of a technological superpower. From Huweai and 5G to TikTok and viral social media, China is stride for stride with the United States in the world of computing. However, China's technological renaissance almost didn't happen. And for one very basic reason: The Chinese language, with its 70,000 plus characters, couldn't fit on a keyboard.  Today, we tell the story of Professor Wang Yongmin, a hard headed computer programmer who solved this puzzle and laid the foundation for the China we know today. This episode was reported and produced by Simon Adler with reporting assistance from Yang Yang. Special thanks to Martin Howard. You can view his renowned collection of typewriters at: Support Radiolab today at