Gene therapy for Bubble Baby Syndrome and risks of leukaemia
Bubble baby syndrome, known as X-linked severe combined immunodeficiency (X-SCID) is caused by a genetic condition that affects the immune system. In contrast to CGD, babies born with X-SCID need to be shielded from all infections at birth and have to be kept in a sterile environment, 'a bubble', or they can die in their first year from infections such as pneumonia or chicken pox. Gene therapy for X-SCID, pioneered by Great Ormond Street Hospital, has been used to treat 10 children who were unable to find a suitable bone marrow donor. It has been extremely successful in restoring the children's immune function enabling them to live fuller and healthier lives.
Unfortunately, as with all medicines, there can be side effects. One of the first children in Britain to receive gene therapy for 'bubble baby syndrome' has developed leukaemia as a result of his treatment.
Professor Thrasher comments 'This development has been the only negative one in the UK following gene therapy. This is distressing news for all concerned but has to be weighed against the life-saving potential of gene therapy for many people with genetic conditions. Clinicians and affected individuals and their families have to carefully weigh up the risks and benefits of gene therapy. While 80 per cent of children with leukaemia make a full recovery, untreated X-SCID is always fatal.'
As with all gene therapy trials, including those for CGD, independent extensive and detailed counselling of the benefits and risks associated with this type of treatment is given to patients and their families. 'Gene therapy is saving lives for people with many disorders such as CGD, X-SCID and a similar condition, known as ada-SCID', said Professor Thrasher. 'This is complex cutting edge medicine, and unfortunately as with any other form of medicine with gene therapy you can't expect not to have some adverse events. Patients dying after a complication following a new type of life-saving heart surgery would not cause such alarm. We have to get gene therapy into mainstream thinking about medicines in general rather than it being treated as a special case. The more that is understood about why this occurred we will be better able to develop safer and more effective gene delivery tools'.
The first X-SCID trial was completed over a year ago while preparations are made for a new trial to open in 2008. Professor Adrian Thrasher said 'We are designing new gene delivery tools for X-SCID and CGD at present that will minimise the risk of inadvertently switching on a cancer gene. We are making improvements to the safety profile of gene therapy and at the same ensuring that gene therapy remains clinically beneficial. There is no doubt that these problems will be solved, in the same way that other forms of medical treatment have matured over the years to become almost routine'.
IMPORTANT NOTE :
The information contained on this website is intended only as a guideline, not as a substitute for medical advice. Always consult your doctor if you or your child has any CGD symptoms or concerns.
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Trust
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