The first stem cell transplant performed on an adult sickle cell patient in Canada has been heralded as a massive success. Twenty-six-year-old Revée Agyepong from Edmonton, Alberta, was declared cured and disease-free on Tuesday.

Sickle cell anemia is a chronic condition currently affecting around 90,000 Americans, the majority of which are of African descent.

The disease is the product of a genetic mutation that changes the structure of the blood's hemoglobin from a circular to a crescent shape. This distortion can get in the way of a healthy blood flow, raising risk of clotting and, in severe cases, causing organ damage, severe pain, and stroke. Average life expectancy for people with sickle cell anemia ranges between 40 and 60 years old.

Before surgery, Agyepong had to visit the hospital once every eight weeks to receive a three-hour-long red blood cell exchange to manage the condition. She had to have her gallbladder taken out and her spleen doesn't function as a result of her disease. She also suffers from heart murmurs and chronic pain.

Agyepong's sister, Stephanie Amoah, was the first to investigate the possibility of a stem cell transplant.

“It was a no-brainer,” she told the Calgary Herald. “I knew if I was a match, I’d just do it no matter what.”

To avoid serious complications, medics say it's best to have donors who are siblings, but even that doesn't guarantee a match. There was just a 25 percent chance Agyepong's body would accept her sister's stem cells.

“I was just excited to know we would get the HLA testing which is the compatibility testing,” said Agyepong, reports CTV News Calgary.

“We hoped for the best, crossed our fingers, and then, on her birthday – which is crazy, we got the best news ever; that she was a ten-out-of-ten match.”

The operation took place at the Tom Baker Cancer Centre last November. While there are expected to be side effects from the anti-rejection drugs for another year or so, the blood tests taken on Tuesday show it's been a success.

“Over the past few months, what we've seen is that Revée's sister's bone marrow has taken over the production of Revée's red blood cells," leader of Alberta's bone marrow transplant program, Dr Andrew Daly, told CTV News Calgary. "The amount of sickle-cell hemoglobin in her bloodstream has decreased almost to zero."

Stem cell treatments like this one have been performed on children, but it's only recently that studies have even begun looking at applying the treatment to adults. The research so far has been promising: A 2014 study turned out an 87 percent rate among 30 adults aged 16 to 65 who had undergone transplants.

Agyepong hopes her experience will pave the way for other sickle cell patients to receive similar treatments.