The cause of a type of hereditary blindness has been traced to a genetic mutation, a discovery that potentially opens a new treatment approach, Canadian and international researchers say.
The inherited eye disease, called Leber congenital amaurosis, usually shows its first signs at birth or in the months following. It affects about one in 80,000 newborns. About 1,000 Canadians live with the effects.
Scientists at Montreal's McGill University and their co-authors have identified that a gene called NMNAT1 can cause LCA.
"We're getting closer to finding 100 per cent of the genes causing Leber congenital amaurosis," said Dr. Robert Koenekoop, director of the McGill Ocular Genetics Laboratory, who led the research team. "That gives an immediate relief to the families, because it confirms the diagnosis [and] gives you a treatment avenue."
The disease was considered untreatable, but that is no longer the case for some subtypes, Koenekoop said.
For the study in this week's issue of Nature Genetics, scientists analyzed the genomes of 60 infants with LCA of unknown cause.
They discovered a mutation on the NMNAT1 gene, which is found in all human cells. It produces a coenzyme called NAD that is involved in hundreds of reactions.
Seeing the sky
The new findings suggest that NMNAT1 acts to protect photoreceptor cells in the retina from degeneration in response to damage or stress.
Dale Turner of Toronto grew up with limited central vision from LCA until an experimental gene therapy surgery four years ago restored much of his vision.
"On the third day, I peeled back the patch and I was able to see things like never before," Turner recalled. "The sky was the most blue I'd ever seen it. I couldn't really see colours before the gene therapy procedure and I could after. I think that just represents so much hope."
Turner's experience has already helped doctors learn to recruit patients and design a clinical trial, which could speed up the next round of research, Koenekoop said.
The other authors of the study were from Houston; Chicago; Cleveland; London; Lahore, Pakistan; Shanghai; and Leeds, U.K., while steering committee members came from Ottawa, Vancouver, Calgary, Toronto and St. John's.
The research was funded by the Foundation Fighting Blindness Canada, Finding of Rare Disease Genes in Canada (FORGE Canada), Genome Canada, the Canadian Institutes of Health Research, Ontario Genomics Institute, Genome Quebec and Genome British Columbia.
It Began In The Netherlands
In 1977, <em>The Economist</em> coined the term "Dutch Disease" to describe the phenomenon of economies whose industrial bases suffer when large deposits of energy, such as oil or natural gas, are found. The magazine named it "Dutch Disease" because of the rapid deindustrialization seen in the Netherlands in the years after a major offshore natural gas find in 1959.
One of the effects of becoming an energy-exporting country is that speculators will start treating that country's currency as a "petro-dollar." The value of the currency rises (and sometimes falls) with the cost of the country's energy exports, which often means it becomes too high in value for exporters in other sectors. Those exporters then see their sales decline, and manufacturing suffers as a result.
As the energy export sector grows, it attracts workers from other sectors, including manufacturing, leaving fewer skilled people to fill jobs in those areas. This is known as "direct deindustrialization."
The Spending Effect
As money flows to the energy exporters from energy consumers around the world, it increases the amount of spending cash people have. That additional cash increases the demand for non-manufacturing labour -- things such as beauty salons, travel, entertainment -- which in turn sends people into those jobs, and away from manufacturing. This is known as "indirect deindustrialization," or "the spending effect."
Economists are in disagreement about whether Dutch Disease is real, whether it's an important phenomenon, and whether it actually happened in any given economy. Fifty years after the Netherlands' big natural gas find, there is no consensus on whether the country experienced the disease named after it, with many economists arguing excessive social spending was behind manufacturing's decline.
The Canadian Debate
In Canada, Dutch Disease has become a highly polarized political issue. When NDP Leader Thomas Mulcair and Ontario Premier Dalton McGuinty recently referred to what they see as the problem of manufacturing suffering under the weight of a booming oil industry, it prompted accusation of divisiveness from leaders of Western provinces. Economists don't agree either. While a recent study from the Pembina institute argues the phenomenon is real and having a negative impact, others argue the strength of Canada's oil sector is creating internal demand that's offsetting the loss of manufacturing exports. Yet others say Dutch Disease is only a part of the problem, and that other factors -- like offshoring of jobs to developing countries and increases in productivity -- are also to blame for manufacturing's decline.