Chinese scientist helps team illuminate gene behind rare eye disease

A team of international researchers, led by a scientist based in Hangzhou, has pinpointed a previously unknown cause of a rare eye disease.

They hope the discovery, which was published last week in the scientific journal Nature Genetics, will help in the creation of new treatments for millions of people around the world who are left in the dark because they lack effective therapy options.

The research team linked an elusive gene called NMNAT1 to a degenerative eye disease known as Leber's congenital amaurosis (LCA). The journal said that three separate teams from around the world had confirmed the same discovery through findings from their independent research.

LCA appears at birth or within a child's first year, and it can cause retinal problems ranging from poor eyesight to complete blindness. The effects are irreversible, and not all of the causes have been identified.

But researchers led by Dr Qi Ming , with the First Affiliated Hospital of Zhejiang University's School of Medicine, have made what they consider a great leap forward in finding a new form of gene therapy for millions of people afflicted by the disease. It strikes about three out of every 100,000 people globally, he said.

Previously, scientists knew of 17 genes whose mutations could cause LCA. But those genetic mutations accounted for just 70 per cent of all cases. The findings may help to shed light on the remaining 30 per cent.

Qi said his research began several years ago, when one of his counterparts, Dr Pei-Wen Chiang of the Casey Eye Institute, in Portland, Oregon, encountered a patient whose disease could not be traced to any of the 17 genetic mutations previously associated with the disease.

So the team began running extensive tests, and last year the researchers - including scientists in the United States and Shenzhen - tried a new method of screening the patient's thousands of genes. They identified 10 with problematic mutations.

Upon further review, they discovered that only the NMNAT1 gene had two types of mutations, rather than just one mutation found in the remaining nine. This was significant because LCA is a recessive disease, meaning that a mutated gene will generally have to come from both parents for a person to be infected.

'A person should have two mutations in the gene - one mutation coming from the father and one coming from the mother,' Qi said. 'Therefore, we identified NMNAT1 as the cause of the disease.'

The team then conducted gene tests on the patient's parents, and the results confirmed their discovery.

NMNAT1, however, is no stranger to scientists. It has long been known to play roles in the heart, nerve cells, liver and kidneys. It had just been previously overlooked.

Lending credibility to the discovery, Qi said, was that the three teams had identified the same gene as the culprit in some LCA cases. The discovery is expected to reach clinical applications through a form of gene therapy in the next three years, by injecting healthy NMNAT1 genes into the eyes of patients with LCA.

Dr Fu Mingshui , an ophthalmologist at the Shanghai No 1 People's Hospital, called the discovery significant. Still, Fu stressed that gene treatment based on the new discovery would take many years, so people living with LCA should not hope for a cure until all the kinks were worked out.

90%

of mainland youth have myopia, or short-sightedness - three times the rate among American children, a US media report said this year