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Aussie study uncovers genetic cause of MacTel


Melbourne researchers have identified an additional seven regions in the human genome that increase the risk of macular telangiectasia type 2 (MacTel), with one particular mutation raising the likelihood of the condition five-fold.

The study out of the Walter and Eliza Hall Institute of Medical Research (WEHI) –  Australia’s oldest medical research institute – builds on their earlier work that found MacTel was associated with low levels of serine, an amino acid used in many pathways of the body.

MacTel affects one in 1,000 Australians, but because early signs of the disorder are subtle, it is difficult to diagnose.

Led by WEHI Professor Melanie Bahlo with Dr Brendan Ansell, Dr Victoria Jackson and Dr Roberto Bonelli and published in Communications Biology, the research is said to provide a new genetic risk calculator for predicting retinal disorders.

Professor Melanie Bahlo says MacTel is a unique eye disease caused by slight changes to levels of fundamental amino acids that have no impact on any other part of the body. Image: WEHI

One of the most notable findings was the identification of a rare mutation in a gene – called PHGDH – which dramatically increased the risk of developing MacTel.

“These new findings further increase our understanding of retinal biology and the way the eye uses energy,” Bahlo said.

“People with this newly discovered PHGDH mutation are five times more likely to develop MacTel than people without this genetic mutation.”

Bahlo said MacTel is a unique eye disease 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,” she said.

Bahlo said the findings could help improve 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,” she said.

“This disease is really hard to diagnose, so understanding the risk factors will allow clinicians to better predict and treat the condition.”

The study was conducted in collaboration with The Lowy Medical Research Institute in the US and the UK’s Moorfields Eye Hospital.

Funding was provided by the Lowy Medical Research Institute, the National Health and Medical Research Council, the John and Patricia Farrant Foundation and the Victorian Government.

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