Shedding light on Leber Hereditary Optic Neuropathy
Duncan Meerding has lived with the rare genetic eye disease Leber Hereditary Optic Neuropathy since his teens. Now new research is providing fresh insight about the number of Australians affected by the condition.
It was just an average Friday morning when then 18-year-old Duncan Meerding realised he had a major problem with his vision.
“I couldn’t see the TV screen,” recalls Duncan, who is now in his 30s. “I was moving my hands about for perspective and I noticed there was a giant blind spot in my left eye. I was like, ‘Ah, I could just be overtired’.”
But it wasn’t a simple matter of fatigue. After visits to doctors and eye specialists, the diagnosis came in: Duncan had the rare genetic eye disease Leber Hereditary Optic Neuropathy (LHON).
The disease causes sudden, painless and permanent central vision loss – usually, first in one eye and later the other eye.
Typically, people with LHON still have peripheral vision (side vision), but the profound central vision loss makes reading, driving and recognising faces difficult.
Within eight months, Duncan had lost central vision in both his eyes and his new life living with significant vision impairment had begun.
The LHON gene is automatically passed down from a mother to all of her children.
However, it is an uncertain diagnosis because not everyone with the mutation will lose their vision, and it is difficult to predict who will lose vision.
Understandably, families with the gene can be extremely anxious about the future. But now a new research collaboration led by the Lions Eye Institute and Centre for Eye Research Australia is providing new insights into the prevalence of the disease in Australia and the risk of vision loss.
The study, published in the American Journal of Human Genetics, shows the overall risk of losing vision if you have the LHON gene is 17.5 per cent for males (one in six males) and 5.4 per cent for females (one in 20 females).
This is significantly less than the popularly quoted risk of 50 per cent for males (one in two males) and 10 per cent for females (one in 10 females).
The study, led by Lions Eye Institute’s Professor David Mackey and CERA Principal Investigator Dr Isabel Lopez Sanchez with colleagues from Flinders University, Save Sight Institute, Royal Brisbane and Women’s Hospital, Menzies Institute for Medical Research and Martilinex LLC, is the largest study of LHON in Australia since the 1990s.
It presents the most up-to-date statistics of the disease in the world and builds on 30 years of dedicated clinical work by Professor Mackey.
CERA Research Orthoptist and Associate Genetic Counsellor Lisa Kearns says, thanks to the study’s findings, people with the LHON gene will be able to understand the condition better and talk about whether they or their children are likely to lose vision from LHON.
With accurate information, people will also be able to make informed family planning choices.
“In some cases – such as large, extended LHON families – people could also be informed of the actual risk of vision loss within their own family,” Ms Kearns says.
LHON is caused by genetic changes (mutations) in the DNA of the mitochondria – the powerpacks that provide energy to our cells.
The research could also help people make choices about a type of assisted reproductive technology called mitochondrial donation, which may become available in Australia in the future.
Mitochondrial donation is where healthy donated mitochondria are used to help conceive children and stop LHON being passed down to the next generation.
Mitochondrial donation is currently only approved in the UK and is being considered by the Australian Parliament.
The Mitochondrial Donation Law Reform (Maeve’s Law) Bill was introduced into the Australian Parliament for debate in March 2021.
Traditionally, LHON has been known as a young man’s disease. However, the latest research confirms LHON can also affect a small number of women, older adults and younger children.
Dr Lopez Sanchez, who leads CERA’s research into Mitochondrial Biology and Disease, says because LHON is very rare, some ophthalmologists may have never encountered a patient with the disease.
“We want them to consider LHON could be a possibility if a woman, younger child or older adult has lost their vision, to avoid a delayed diagnosis or even misdiagnosis,” she says. “This will help ensure people can access appropriate support, care and genetic counselling.”
The new study counted, for the first time, how many families in Australia have the LHON gene.
It found 96 families currently have the gene and 355 people are currently living with vision loss because of it.
Dr Lopez Sanchez says this data will provide researchers with a comprehensive database of people they can approach if there are clinical trials and studies in the future aiming to prevent or treat vision loss.
“It will also help us design accurate trials and studies, which is very important, as that will help us develop efficient treatments,” she says.
It will also help researchers keep LHON families informed about mitochondrial donation, which could become available in Australia in the future.
Learning to thrive
Duncan recalls losing his vision was, initially, “psychologically and physically difficult to deal with”.
“Luckily, I had great support from doctors and my Uncle Doug, who also has vision loss from LHON. Because of that support, I came to realise having LHON wasn’t the end of the world – it was the beginning of something new,” he says.
Duncan is an award-winning furniture and lighting designer who found his career path after completing a Bachelor of Arts degree at the University of Tasmania.
His design skills have given him many rich experiences, including being engaged by the University College of London to travel to England to teach a world-first course called Architecture Beyond Sight to architecture students with vision impairment.
“Vision loss has informed my life,” he says.
While welcoming the study’s findings, Duncan encourages anyone with LHON or a similar condition to carve out a life in the here and now.
“Live your life as someone with vision loss – don’t put off your life,” he says. “If and when treatment comes along, that will be great but, in the meantime, learn how to adapt.”
Way of the future
Dr Lopez Sanchez is hopeful solutions will be found in coming years to treat and prevent LHON.
“Technology is developing very fast,” she notes. “In the future, gene therapy, for example, is expected to be a game changer for genetic eye conditions.”
Dr Lopez Sanchez is now researching why some people with the LHON gene lose vision while others have good vision for life.
“Some families have a much higher risk of vision loss than others and we believe there could be another gene behind that,” she says. “We aim to identify it and, in the future, use technology to help prevent that risk.”
The study was possible thanks to the support and work of many people, including LHON families, referring clinicians, the LHON Facebook support group and genealogical researcher Maree Ring.
CERA also receives funding from the Victorian Government’s Operational Infrastructure Support Fund.
Read the study
Isabel G. Lopez Sanchez, Lisa S. Kearns, Sandra E. Staffieri, Linda Clark, Myra B. McGuinness, Wafaa Meteoukki, Sona Samuel, Jonathan B. Ruddle, Celia Chen, Clare L. Fraser, John Harrison, Alex W. Hewitt, Neil Howell, David A. Mackey Establishing risk of vision loss in Leber Hereditary Optic Neuropathy. American Journal of Human Genetics https://doi.org/10.1016/j.ajhg.2021.09.015