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GM/GE Implications for Treatment of Muscular Dystrophy :  A letter to the Editor of ‘In Touch’- Magazine of the Muscular Dystrophy Association of New Zealand - April 2002

Dear Editor,

In the editorial of your Feb/March edition of In Touch, Ronelle raised questions about GM or GE. In addition to wondering if the phrase that is used actually matters, she specifically wondered if this kind of "evolutionary tampering would do great things for my body", and by implication those of other people with MD. She implied "no", by opting for the "devil you know".

Can I advise you and the members of your association of one GM/GE treatment that has successfully treated in clinical trials in Holland, several children who have a fatal infantile form of a disease known as Pompe disease, otherwise known as Glycogen Storage Disease Type 2, or Acid Maltase deficiency.

The symptoms of this disease have been likened to a combination of Muscular Dystrophy and Cystic Fibrosis, though that is my lay description, not a clinical one, and for those with the classical infantile form of this disease, it is always fatal in the first year of life.

There are other later onset versions of this disease that may be familiar to some in your organisation, and the symptoms are severe and debilitating for most affected people.

This disease is caused entirely by a single genetic defect, that in turn results in a deficiency of Alpha-glucosidase, and the absence of this enzyme leads to an inability to break down Glycogen in the muscles, leading to the symptoms of the disease. The cause of the disease has been known for some time, and the theory of how it might be treated, has also been known. The problem was how to produce this complex human protein so that it would be received by the patient's cells, and release the stored Glycogen from the muscles, without producing immune reactions or causing other problems.

The remarkable thing about all this is that the successful treatment of the children came about by the production of a replacement alpha-glucosidase protein in the milk of a transgenic rabbit. One of the children, Bart, has survived as a healthy child more than two years beyond the time he certainly would have died without treatment, and all 9 patients in the trial are doing well on the treatment.

Work is under way to scale up production of this enzyme to make it available to all affected patients, and it is clear that this GM/GE product has produced an effective treatment for this severe form of Muscular Dystrophy. Although the transgenic rabbit will not be used for the wider production (simply because there are problems getting enough rabbit milk produced) the production will still use GM/GE techniques using Chinese Hamster Ovary cells in a batch fermentation process.

I am familiar with this story because Pompe disease is also a Lysosomal Storage Disease, and I am the Chairperson of Lysosomal Diseases New Zealand. Further information on these diseases can be found on our website at www.ldnz.org.nz

To come back now to Ronelle's questions in the editorial - there is no doubt that the production of a replacement human enzyme of this complexity, that was also capable of successfully treating this disease, could not have been done without the sophistication and biotechnology of GM/GE. Another way of phrasing this, is that GM/GE opens possibilities for treatment of complex diseases, that current or traditional medical science cannot offer any solutions to. Without GM/GE it would have been impossible.

In the near future we can expect to see more breakthroughs of this nature. Within the Lysosomal group of disorders, two have treatments available now, two more (including Pompe disease) are close to production, two others are at advanced clinical trial stages, and several others are expected out of the laboratory and into clinical trials, soon. Remarkable indeed when just ten years ago there was no enzyme replacement therapy available at all for any of them. All have become a reality because of Genetic Modification.

And that brings me back to the phrase issue, GM or GE. Some prefer one and some the other. Some see the emphasis on "engineering" as more perjorative, and this phrase is often preferred by those who oppose GM/GE. In my view the phrase is irrelevant if the medicine works, so I have used both together and regard them as interchangeable.

And finally, some implications for New Zealand and a very topical issue. Next time you hear debate about AgResearch producing transgenic cows, and whether this is good or not, think of the potential for production of a variety of therapeutic human proteins for medicinal use from these cows, and think of the quantities likely to be produced. Our transgenic animals may not breed like rabbits, but they will milk like cows!!

In my role as the Executive Director of the NZ Organisation for Rare Disorders I have made submissions to ERMA to support AgResearch's application for their cows, and I made detailed submissions with others to the Royal Commission on Genetic Modification, to support continued research into such solutions. A lot of my time and energy goes into education on these matters.

I hope that the population of NZ, and in particular those within health and disability support groups, will soon realise the enormous benefits we are currently receiving from GM/GE, and the wave of benefits it will also deliver soon.

Other questions may arise about this information, such as why I deliberately refer to Pompe as a disease rather than as a disability. That would need another lengthy letter of explanation that also looks at some of the deficiencies in an otherwise very good NZ Disability Strategy. I am happy to respond to further questions on these matters.

Yours sincerely,