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Unlocking the secrets of blindness
Tom Spears
Joanne Gaida has lived most of her 24 years with "a quiet paranoia," a constant fear that the hereditary condition that tore apart the inside of one eye might make her other eye blind, too.
She wasn't allowed any rough-and-tumble play, and her mother would check her vision every time she fell off her bike to make sure nothing had torn her fragile retina.
Now the Trenton woman and her husband want children of their own.
But they know each child would have a 50-per-cent chance of inheriting the same condition, and wondered how they would manage the years of watching and asking: Is it this child? Or that one? Will my kids lose their sight? With dozens of other family members, they have joined a genetic study at the Ottawa Eye Institute that is now returning enormous dividends.
Not only have doctors there found the gene that causes the rare eye condition called Wagner's disease, but they can use this to test newborn babies and carry out the preventive care that will protect their sight. A simple blood test will eliminate the stress and expense of testing those children who haven't inherited the gene -- complex and difficult tests that must be repeated every few months for a lifetime.
It will also show which children need the preventive laser treatment that removes weak spots in the retina -- the cells at the back of the eyeball that will eventually rip away from their base and destroy the patient's sight, usually in adolescence. Early laser treatment lessens the likelihood that serious tearing will occur later.
And that usefulness in real patients is what sets this gene finding apart from the hundreds of disease genes whose discovery has not yet led to any treatment.
"This is a major factor, knowing that such screening is available," Mrs. Gaida said yesterday at the Eye Institute.
The four doctors who made the discovery are delighted that there's finally a tool to show who has this disease.
"This is certainly quite a devastating disorder," said Dr. Sanjoy Gupta. "It causes blindness."
The Eye Institute took an unusual approach, bringing together the doctors who treat patients with researchers who would normally stay in the lab. In this case, the two are just steps apart, as the Ottawa Health Research Institute is just down the hall from the Eye Institute at the Ottawa Hospital's General campus.
Staff in lab coats mingle with surgeons in green surgical outfits, and most, in fact, share an interest in both worlds. Dr. Gupta had a PhD in genetics before becoming a medical doctor.
All they needed to trace the mysterious cause of Wagner's disease -- a condition so rare only a handful of families in the world are thought to be affected -- was a big family that carried it. So they turned to Joanne Gaida's mother, Marie Harvey of Ottawa.
Mrs. Harvey has four children, two of whom have the disease. Her late husband was one of six children, and three had it.
So Mrs. Harvey asked her mother-in-law for as complete a list of family members as she could supply, noting which ones had the disease. The many branches of her husband's extended family, commonly known as the Gervais clan, are scattered from here to Nova Scotia, but are concentrated in Eastern Ontario and West Quebec.
At first the doctors thought they were dealing with two large families until someone dug up a link between the two, seven generations back, showing the whole group is in fact related. Nearly half the 300 known Gervais family members have the disease.
"These are quite complex retinal tears. They are very difficult to repair," Dr. Gupta said. "Twenty years ago a patient would walk into an emergency department with complete retinal detachment (i.e. a retina torn away from the back of the eye) and no hope of repair." They went blind.
Most people with the disease need laser repairs to the retina, and about 60 per cent need further surgery. Even still, many of the older members of the Gervais family are blind. It's only the young ones whose sight has been partially preserved.
An exhaustive genetics study of blood from 54 family members found everyone with Wagner's disease has the same eight "markers," a genetic fingerprint that sets them apart from those with healthy eyes.
The gene involved helps regulate how the body makes collagen, a sort of chemical glue that holds tissues together in many parts of the body. This particular collagen gene only becomes active in the jelly-like material that fills the eyeball; in Wagner's disease this "vitreous" jelly grabs too tightly to the already weak retina and pulls it away.
Dr. Gupta and fellow researchers Brian Leonard, Karim Damji and Dennis Bulman have published their discovery in the American Journal of Ophthalmology. It is based on five years of work, with funding from the E.A. Baker Foundation, part of the CNIB.
"Where this will have the greatest effect is with kids, because kids can be affected and they're extremely hard to examine" for possible eye disease, Dr. Gupta said. "So often, kids are not known to be affected ... until they're much older" and eye damage has begun.
"This is now life-changing," said Dr. Damji. "This is an easy test to do, and fortunately the Children's Hospital of Eastern Ontario has agreed to carry out this test for family members."
Dr. Leonard, the founding director-general of the Eye Institute, sees a bright future for this cross between the research lab and the front-line doctors.
"We love it," he said. It's looking now at how newts grow new, fully functional eyes if they lose one, hoping for lessons that would apply to regenerating human corneas.