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Monday, 4 January, 1999, 22:14 GMT
Haemophilia cure works on dogs
Haemeophilia Society
Haemophilia Society welcomed the research
Scientists are developing a treatment for a form of the blood clotting disorder haemophilia.

Researchers from the University of North Carolina have successfully treated dogs with haemophilia B using gene therapy.

The inherited illness, also known as Christmas disease, causes victims to bleed spontaneously, live severely restricted lives and often to die prematurely.

A malfunctioning gene that fails to stimulate production of a blood clotting protein known as factor IX is thought to cause haemophilia.

The scientists, who reported their findings in the journal Nature Medicine, treated dogs with his protein deficiency by injecting them with a corrected form of the gene.

The dogs started to produce factor IX, and are continuing to produce it steadily more than a year and a half after treatment

Dr Timothy Nichols, associate professor of medicine and pathology at University of North Carolina Chapel Hill School of Medicine, said: "This level of correction in humans could be enough to improve certain people with severe hemophilia, who bleed spontaneously, to the point where they would only bleed when injured. That would be a major improvement."

The dogs come from a strain that has been bred by the university for more than half a century. They inherit haemophilia in a similar manner to humans.

The researchers found that the more corrected gene the dogs received, the more strongly their bodies responded.

They are confident that the research will help them to determine the correct dose to give to humans.

Two techniques were tested on the dogs. In one the genes were injected into the muscles, and in the other they were injected into the blood vessels leading into the liver, where factor IX is normally made.

Dr Nichols said: "We reasoned that if you could just give patients a shot into muscle, gene therapy could work with little or no sedation, and it would be easier to get a clinical trial going and easier on patients.

"We think the new work tends to confirm that."

The genes were injected into the dogs inside a flu-like virus that had been rendered harmless.

Thousands are affected

Queen Victoria
Queen Victoria carried haemophilia
Haemophilia B affects up to about 50,000 people worldwide.

A synthetic version of factor IX made from hamster ovaries is available, but hugely expensive.

Alternatively, patients can receive factor IX derived from human blood plasma, but in the past supplies have been contaminated with HIV and hepatitis C.

In both cases patients need approximately three injections a week to keep their factor IX up to a sufficient level - approximately three per cent of that of a normal person.

Dr Nichols said: "From an expense point of view, the total cost of treating these patients is just extraordinary, especially when you think of it over a lifetime.

"The new work suggests that it's conceivable that appropriately selected patients could come into a clinic, get one or more shots that take less than an hour to administer and still be making clotting factor a year or two later. That would have a huge beneficial impact both for patients, who now have to come in several times a month, and their health-care costs."

The Carolina researchers plan to test similar techniques on dogs with haemophilia A, a different form of the illness caused by inadequate factor XIII production. It is about ten times more common than haemophilia B.

Chris Hodgson, chairman of the Haemophilia Society, said: "We would certainly give this work a cautious welcome.

"If the production of factor IX can be promoted by gene therapy it would be a great step forward."

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