Eye can see clearly now

By Patrick Boyle

If you are one of the 30 per cent of Canadian citizens who suffer from the condition known as myopia or, more commonly nearsightedness, you have probably wondered about the cause of your condition. Have you also wondered if a permanent, non-surgical cure will arise in the near future? If so, perhaps the recent genetic discovery by University of Calgary researcher Torben Bech-Hansen will put your mind at ease.

The findings of his international team of over 50 geneticists provide an explanation of the failure of nerve cells in the eye to connect. They will be published in one of the world’s most renowned scientific journals, Nature Genetics.

"I am excited that we have been able to identify this new gene as part of the Human Genome Project," said Bech-Hansen. "Our research shows that mutations of this gene cause a specific type of night blindness and myopia–something which has puzzled ophthalmologists and patients for decades. Knowing the cause opens the door to finding possible treatments, and hopefully one day a cure."

Finding this gene, which is being called NYX by Bech-Hansen’s research team, was an arduous task.

"Finding human genes the way we do it and most other researchers do it, we don’t know where to look for it," said Bech-Hansen. "It’s like looking for a needle in a haystack."

The research group started by finding families in which several members had Congenital Stationary Night Blindness. It was found that the gene existed on the X chromosome which contains about 4,000 genes. The researchers then determined where on the stretch of DNA the gene exists.

"We recognize the gene has to be a gene that lives in the retina," said Bech-Hansen.

The isolated region contained about 30 genes. From these genes, the team isolated those that are expressed more often in the retina than in other parts of the body. The research group then looked at the DNA of the families who had CSNB.

"We checked five genes, four were normal, one was mutated," said Bech-Hansen. "That tells us this is the one which is not working right because it occurs in each of the patients."

The NYX gene codes for a protein called nyctalopin. It appears this structure plays a crucial role in the transmission of electrochemical impulses between the nerve cells of the retina. Specifically, nyctalopin sits in the junctions of the ON-pathway, which is responsible for vision in dim conditions.

"Basically, you are not able to see things that are dimly lit," said Bech-Hansen.

According to Bech-Hansen, the discovery brings exciting news for sufferers of CSNB and other ocular disorders. The new-found knowledge with regards to the role of NYX in retinal neurotransmission provides significant progress towards the knowledge of mechanisms whereby signals are transmitted in the retina. As such, the discovery creates the possibility not only of a cure for CSNB, but also of therapies of other diseases.

"[The discovery] provides a specific target for therapeutic strategies," said Bech-Hansen. "[It] provides a tool for studying the normal function of the retina, and the secondary problems in patients with complete CSNB."

Gilbert Schultz, the Associate Dean of Medicine was very positive about Bech-Hansen’s findings.

"This brings recognition to not only [Bech-Hansen’s] research program, but to the strength of researchers in the U of C as a whole," said Schultz.

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