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Scientists have used a sophisticated type of gene therapy to treat mice with a form of haemophilia. The experimental procedure is called RNA trans-splicing.
It has been used to repair a mutated section of the gene responsible for the hereditary bleeding disorder.
Haemophilia causes a person to bleed for longer than normal. Cuts and grazes are not great problems as a little pressure and a plaster are usually enough to stop bleeding.
The main problem is internal bleeding into joints, muscles and soft tissues.
If left untreated these bleeds cause acute pain and severe joint damage leading to disability.
Haemophilia A, the most common form of the disorder, affects up to one in 5,000 baby boys.
It is caused by a gene defect which hampers the body's ability to produce a chemical which helps the blood to clot.
Tough task
People with the condition suffer spontaneous bleeding into major joints and soft tissues. It can mean that their lives are imperilled by physical injury.
Currently, haemophilia A can only be treated by injections of the clotting chemical, known as factor VIII.
Previous attempts to develop a gene therapy treatment have floundered.
This is in part due to the fact that the factor VIII gene is large, and therefore difficult to manipulate.
The new technique avoids this problem by only dealing with a small part of the gene
RNA trans-splicing works by injecting fully functioning genetic material which binds to the existing faulty version and corrects it - leading to proper production of factor VIII.
Lab tests on mice saw levels of factor VIII in the blood rise from lower than 1% of the normal level to up to 20%.
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"If the technology is proven effective in humans, it would provide a more permanent treatment for haemophilia A" |
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Dr Hengjun Chao |
This level was enough to make the blood clot in a much more normal way.
Researcher Dr Hengjun Chao of the University of North Carolina School of Medicine, said: "If the technology is proven effective in humans, it would provide a more permanent treatment for haemophilia A."
Fellow researcher Dr Christopher Walsh said: "This new gene therapy tool will help treat haemophilia A as well as a host of other genetic diseases such as cystic fibrosis, sickle cell anaemia, muscular dystrophy and some forms of cancer."
Karen Pappenheim, chief executive of the UK Haemophilia Society, described the research as "very interesting".
Hope for the future
She told BBC News Online: "The research is obviously at a very early experimental stage, but we hope that within 10 years that some form of gene therapy will be made available.
"Haemophilia can be a very severe condition, and although we have good modern treatments, there is still no cure for people, who have to have very regular injections for internal bleeding."
Many children with haemophilia are given injections two or three times a week to keep up their levels of factor VIII.
This is designed to minimise damage to vulnerable joints, such as the knee, ankle and elbow while they are still developing.
However, adults with haemophilia tend to receive treatment only when they have suffered an internal bleed.
In severe cases this can occur 20 to 30 times a year.
The research was presented at a meeting of the American Society of Gene Therapy.
[BBC News Online]
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Last Revised at December 10, 2007 by Lusine Kazoyan, M.D.
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