'Incurable' illness falls to gene therapy

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'Incurable' illness falls to gene therapy

http://www.nzherald.co.nz/section/story.cfm?c_id=2 & ObjectID=10375893

04.04.06

By Steve Connor

Gene therapy has repaired the immune systems of two men who were

born with an " incurable " genetic disorder that made them almost

defenceless against bacterial and fungal infections.

Sixteen months after an operation to repair a defective gene, the

once severely ill patients show signs of complete recovery.

Scientists believe the latest success will lead to further

operations to treat many other chronic and incurable conditions

resulting from the inheritance of defective genes.

Gene therapy involves altering a person's genome to repair or

replace a mutated gene. After years of hype and hope, the technique

seems finally to have proven its potential with a handful of

successful operations.

The latest success was achieved by doctors in Germany, Switzerland

and Britain who treated two men with chronic granulomatous disorder

(CGD), an immunodeficiency disease caused by a defective gene on the

maternally inherited X chromosome.

The men - both in their mid-twenties - suffered repeated life-

threatening infections from bacteria and fungi and from an early age

had to rely on powerful antibiotics and antifungal medicines. Since

their operations 16 months ago at the University Hospital in

furt, both patients have gained weight and have been free of

the severe infections that have plagued them since childhood.

Manual Grez of the Institute for Biomedical Research in furt,

one of the leaders of the study published in the journal Nature

Medicine, said the results suggest that it may be possible to use

gene therapy to treat other similar inherited diseases.

" These are very positive results but there is still a lot of work

needed to make this technology available to all CGD patients, " Dr

Grez said, adding that the work was a " landmark study " .

CGD is rare, affecting about 1 in 250,000 people in Britain, and is

caused by defects in a type of white blood cell known as phagocytes,

which normally engulf and destroy harmful microbes as they invade

the body.

About 60 per cent of CGD sufferers inherit a defective copy of the

gp91phox gene which leaves their bone marrow unable to manufacture

phagocytes with the right chemical machinery for destroying the

microbes.

To repair the problem, the doctors removed stem cells from the

patients' bone marrow, inserted a healthy copy of the gp91phox gene

into the cells while culturing them in the laboratory, and then

inserted the engineered cells into the patients' bone marrow.

To increase the chances of the genetically altered stem cells

repopulating the bone marrow, the doctors partially destroyed the

patients' own bone marrow.

Professor Thrasher of the Great Ormond Street Hospital in

London, who has performed similar gene therapy operations involving

other cells of the immune system, said British CGD patients could be

next.

" Further improvements and refinements in the technology are now

under way to maximise the effectiveness and safety of the system, "

he said. " This is a step towards the definitive cure of CGD but

there is still a lot of work to be done, "

The work was carried out with the help of the CGD Research Trust

which has spent £1.2 million ($3.4 million) over the past eight

years to promote gene therapy. Liz , the chief executive,

said: " We believe gene therapy may eventually help many people with

genetic disorders, and this early work must be supported. "