Josh McQuillin, right, of Prince George, B.C., who is the first Canadian in history to receive a direct intravenous injection gene replacement therapy, undergoes tests at the University of Calgary's clinical trials unit in Calgary, Alta., Thursday, March 14, 2019. THE CANADIAN PRESS/Jeff McIntosh

CALGARY - A big sushi meal would have once made Josh McQuillin gravely ill, but the British Columbia man can now gorge on one of his favourite foods worry-free thanks to a clinical trial for his rare genetic disorder.

McQuillin was 12 when he was diagnosed with urea cycle disorder, a life-threatening condition that causes ammonia to build up in the body and can put a person in a coma.

He had to strictly limit how much protein he ate and took expensive medication several times a day. He could never be too far from a hospital, which made it hard to travel abroad or join friends backcountry camping.

"Now I can eat as much protein as I want. I'm eating differently, sleeping differently, exercising differently," McQuillin, 30, said during a monitoring appointment at Calgary's Foothills Medical Centre on Thursday.

"I've gained a bit of weight. I've never had to fight weight gain before, which is kind of funny. I've always been underweight my whole entire life."

The genes needed to process ammonia were delivered to McQuillin's liver intravenously. A virus, modified to be harmless, was used as a transmitter.

Aneal Khan with the University of Calgary's Cumming School of Medicine said McQuillin is believed to be the first Canadian to receive intravenous gene replacement therapy for urea cycle disorder.

McQuillin, who lives in Prince George, B.C., said he felt the results two weeks after the one-time injection.

Khan is leading the Canadian portion of an international clinical trial on gene therapy for urea cycle disorder. He also treated McQuillin in Ontario when he first got sick as a boy.

Khan recalled telling McQuillin's parents years ago that he wasn't sure their son would survive.

"Since he's had this therapy, his ammonia has not gone high, despite him eating whatever amount of protein he wants. It's a massive change," said Khan. "We're very excited — especially for rare genetic diseases, DNA diseases — that we don't have to tell the parents that stuff anymore."

Khan said similar strategies have shown promise for treating other genetic diseases involving the liver, such as hemophilia.

Alberta Health Services has set aside beds in Foothills hospital's intensive care unit for clinical trial patients. That's important, because it's often not known whether an experimental treatment will have serious adverse effects, said Christopher Doig, a medical director in intensive care for the agency's Calgary zone.

"They can get it in a very safe way where they can be very closely watched, very closely monitored. At the same time, we're not using resources taking away from other patients."

McQuillin said he's looking forward to going on a road trip in the United Kingdom this spring without having to worry about his medication or whether the nearest hospital can treat his condition. He can also rest easier when on his forestry job, which once required painstaking meal planning for trips into the bush.

"Everything's 100 per cent good to go for now," he said.

"I guess my only concern or fear is they don't know really how long it will last. But it's definitely exciting."

Note to readers: This is a corrected story. An earlier version, based on information provided by the University of Calgary and Alberta Health Services, said McQuillin was the first Canadian to receive gene replacement therapy intravenously and that Aneal Khan led the entire clinical trial.

News from © The Canadian Press, 2019