Genetic flaw shows promise for treating eye disease

A genetic flaw may hold the key to delay or prevent the onset of a serious eye disorder that can result in blindness and vision loss.

Eye Examination. Image Credit: Robert Przybysz/Shutterstock.com

One in every 1,000 Australians are affected by MacTel (macular telangiectasia type 2). Symptoms of this eye condition include difficulty in reading, gradual vision loss, and distorted vision. However, it is hard to diagnose this disorder because its early signs are quite mild.

Now, a research team has detected seven more regions in the human genome that raise the chance of developing this eye disease, such as a rare DNA mutation in the PHGDH gene, which would allow clinicians to diagnose and treat it more effectively.

The study is based on previous studies performed by Walter and Eliza Hall Institute (WEHI), which indicated that MacTel was linked with low concentrations of serine, a kind of amino acid utilized in several different pathways in the body.

The study, headed by WEHI Professor Melanie Bahlo in association with Drs Brendan Ansell, Victoria Jackson, and Roberto Bonelli, and reported in the Communications Biology journal, offers a new genetic risk calculator for estimating retinal disorders.

The study was carried out in association with The Lowy Medical Research Institute in the United States and Moorfield’s Eye Hospital in the United Kingdom.

At a glance

• MacTel is mainly caused by small variations in the concentrations of many essential amino acids in the blood of a person.
• The investigators discovered another rare PHGDH gene mutation that makes individuals five times more likely to develop MacTel, and they also identified seven new genetic regions.
• A better understanding of the genetic mutations that cause the MacTel disorder will enable clinicians to screen for this condition more effectively and possibly prevent it from progressing.

PHGDH increases MacTel risk

The team also observed that a rare mutation in a gene, known as PHGDH, significantly raises the chance of developing MacTel.

Amongst our new gene findings, we identified a new rare mutation in the PHGDH gene. These new findings further increase our understanding of retinal biology and the way the eye uses energy. People with this newly discovered PHGDH mutation are five times more likely to develop MacTel than people without this genetic mutation.”

Melanie Bahlo, Professor, Walter and Eliza Hall Institute

Eye disorder often diagnosed late

According to Professor Bahlo, “MacTel is a really unique eye disease, which is caused by slight changes to levels of fundamental amino acids that have no impact on any other part of the body. What we found is that the disease is driven by two factors; metabolic amino acid on one side and then risk factors related to the cellular health of the retina on the other side, which are probably involved in transporting crucial amino acids into the retina”

“Both of these factors contribute to whether someone is genetically predisposed to getting MacTel in later life,” added Professor Bahlo.

Findings provide hope for improved diagnosis and treatment

According to Professor Bahlo, these results may help enhance the diagnosis and treatment of MacTel.

By understanding the causes of the condition, we can tailor treatment to each individual patient to ensure the best outcomes for them. This disease is really hard to diagnose, so understanding the risk factors will allow clinicians to better predict and treat the condition.”

Melanie Bahlo, Professor, Walter and Eliza Hall Institute

Since retinal disease normally worsens with age, early diagnosis is critical to maintaining vision in patients with this condition.

By diagnosing this condition earlier, patients may be able to take mitigating steps to delay or prevent it developing.”

Melanie Bahlo, Professor, Walter and Eliza Hall Institute

Together with collaborators, the researchers will now perform additional studies to look at ways for detecting more genes involved in MacTel, with the goal to develop better therapeutics and treatments.