Search for:
Genetic Disease Focus: Ataxia–telangiectasia

Ataxia–telangiectasia (AT or A–T), also referred to as ataxia–telangiectasia syndrome or Louis–Bar syndrome is a rare, neurodegenerative, autosomal recessive disease causing severe disability. Ataxia refers to poor coordination and telangiectasia to small dilated blood vessels, both of which are hallmarks of the disease. A–T affects many parts of the body:

Read More
The genetically modified food fight

By Michael Jacobson

Center for Science in the Public Interest 1875 Connecticut Ave NW, Suite 300 Washington, DC 20009;

West J Med 2000;172:220–221.

Image from http://www.healthyfoodhouse.com/
Image from http://www.healthyfoodhouse.com/

The once sedate farm scene has turned into a roiling battle ground, pitting, at the extremes, the growing of organic crops against crops derived from biotechnology. Organic farming eschews synthetic pesticides and fertilizers, whereas crops that are derived from biotechnology are developed through the use of recombinant DNA.

Although most consumers have some awareness of the attributes of organic agriculture, they know little about agricultural biotechnology. However, the increasingly strident controversy over biotechnology may replace that ignorance with confusion. In such an environment, it behooves government—and industry—to build long-term public confidence by establishing strict rules to ensure safety and choice for consumers and to safeguard the environment. And it behooves physicians to respond knowledgeably to questions from patients wishing accurate information.

The US Food and Drug Administration (FDA) is responsible for ensuring the safety and honest labeling of foods, including foods derived from genetically engineered plants (also referred to as genetically modified organisms). The FDA strongly encourages, but does not require, companies to consult with it when they wish to market new genetically modified foods; to date, all companies have done so.

The FDA urges companies to conduct allergenicity studies when a gene is transferred from a plant known to be commonly allergenic (or when a novel protein is introduced). Thus, thanks to premarket testing, a company found that a Brazil-nut gene that it had added to soybeans encoded a known allergen. The company did not market the product. Importantly, the allergen was identified only because it was known and could be tested for. An allergen newly introduced into the food supply (say, from a bacterium) would be difficult to identify.

Critics have raised additional health concerns. For instance, levels of naturally occurring toxins, such as solanine, might accidentally be increased in genetically modified plants. Again, the FDA encourages, but does not require, companies to screen for such substances. It also is conceivable that genetic engineering might engender a novel toxicity, as suggested by a recent controversial study of potatoes that had been genetically modified. If genetic engineering were to cause a behavior disorder or autoimmune disease, or to interfere with a medicine, those risks would be difficult to identify either before or after marketing. Although the same can be said for foods derived by traditional breeding (and, indeed, high levels of toxins have occurred in several strains of traditionally bred potatoes, celery, and squash), we have had comparatively little experience with genetically modified foods.

It is impossible to prove with certainty that something is completely safe, but foods that may be consumed by billions of people must be tested as thoroughly as possible. Although the widespread consumption of foods derived from biotechnology in recent years has not caused any known health problem, the FDA’s current voluntary review system lessens public confidence and should be made mandatory.

The FDA should calibrate testing requirements to a food’s potential for causing harm. For instance, foods containing genes from an organism that causes allergic reactions would require more thorough testing than foods modified only with genes for known, safe proteins. Transfer of a common allergen into another food should be prohibited. And for genetically modified foods in which gene products came from nonfood sources, were present in significant quantity, or whose structure suggested a possible health problem, the FDA could require more extensive testing, possibly including studies of animal feeding, and submission of complete toxicologic data.

Aside from questions of safety for consumers, genetically modified crops might adversely affect the ecosystem. The US Department of Agriculture (USDA) bears the primary responsibility for ensuring that such crops do not adversely affect the environment or agricultural practices more than their nonmodified counterparts, while the US Environmental Protection Agency (EPA) evaluates crops engineered to contain pesticidal material.

These agencies face difficult challenges because genetically modified crops raise genuine ecological concerns. For instance, corn engineered to contain the insecticidal toxin from Bacillus thuringiensis may possibly trigger resistance in pests (such as the corn borer), inadvertently contaminate the gene pool of wild varieties of related species, and kill desirable insects (such as the Monarch butterfly). To obtain independent advice on such concerns, the US Department of Agriculture recently established an advisory committee on agricultural biotechnology and commissioned the National Academy of Sciences to review the department regulatory process. It would be valuable for the FDA to commission an analogous study on safety issues.

Increasingly, consumers are asking that genetically modified foods be labeled. Some manufacturers and retailers are now voluntarily labeling foods and several governments abroad are requiring such labeling. Labeling, of course, should not be a substitute for safety; every genetically modified food should be safe. Yet, even assuming that those foods are as safe as conventional foods, they raise warning flags for people with severe allergies or concerns about general safety. Also, Moslems, Jews, and vegetarians may wish to avoid foods containing genes or gene products derived from animals. Others are concerned that genetically modified crops might cause environmental problems or believe that it is unethical to move genes between distant species. Regardless of what one thinks of the validity of those concerns, labeling would enable consumers to avoid biotech foods. Labeling is supported by most Americans, according to public opinion polls.

The FDA should define the term biotechnology-free and allow marketers of foods that meet that definition to make a label claim. Foods containing genetically modified ingredients should be required to disclose that fact on labels (new legislation may be needed for this). If such a food contained a possible allergen, the ingredient label should indicate the source of the genes (for example, “contains [food] protein”). Finally, steps should be taken to ensure that labeling does not mislead consumers into thinking that genetically modified foods are much riskier or that genetically modified-free foods are much safer than other foods.

Meanwhile, people troubled by genetically modified foods can choose organic foods, the production of which minimizes risks due to pesticide residues in food and water, builds up soil, and protects wildlife.

 

References

  1. US Food and Drug Administration. Statement of policy: foods derived from new plant varieties. Fed Reg 1992 May 29;57:22984-23005.
  2. 2 Nordlee JA, Taylor SL, Townsend JA, et al. Identification of a Brazil-nut allergen in transgenic soybeans. N Engl J Med 1996;334:688-692.
  3. Ewen SWB, Pusztai A. Effects of diets containing genetically modified potatoes expressing Galanthus nivalis lectin on rat small intestine. Lancet 1999;354;1353-1354.
  4. Walsh J. Brave New Farm. Time 1999 Jan 11;153:87. Available at: http://www.pathfinder.com/time/magazine/articles/ 0,3266,17698-1,00.html. Accessed January 28, 2000.
  5. Ferber D. GM crops in the cross hairs. Science 1999;286:1662-1666.
  6. US Department of Agriculture. Advisory committee on agricultural biotechnology. Fed Reg 1999 Aug 19;64:45227-45229.
Transgenesis: The Next Phase of Evolution?

By Tayo Fasuan

TrangenesisFor anybody who has watched the sci-fi movie, The Rise of the Planet of Apestransgenesis would of course be a real concern. In fact, it is actually scary giving the rate at which genetic scientists are modifying everything in the name of improving the quality and quantity of desired characteristics. For those who haven’t watched the movie, let me provide a brief summary.

In the movie, a gene therapy drug experiment to find a cure for Alzheimer using a modified virus resulted into mutation in the experimental chimpanzees, making them have a human level intelligence. In the ensuing scenes, a particular ape emerged called Caesar, borne by a genetically-altered female chimp, and developed rapidly in terms of intelligence which is amazingly at human level, and at times above that level. Later in the movie, Caesar ultimately talked.

Eventually, the mutated apes revolted, the modified virus wiped out the human race through an epidemic, and the apes, which are somehow resistant to the virus, became the next dominant being on earth. Call it a science fiction movie but with recent advances in the field of molecular genetics and biotechnology, I know it is possible.

When the first cloned animal was ‘made’– I can’t use the word ‘born’, can I? –, there was celebration in the scientific world, so much that the animal, a sheep, was named Dolly, after the country singer Dolly Parton for reason still unknown to many including me. These even made the effort at sequencing the complete human genome to continue at a more frantic pace. However, this euphoric feeling was short-lived as the world – of course, through the works of the media/movie industries releasing news and movies about cloning– became aware of the ‘danger’ inherent in cloning a human being.

Legislations and ethics were made to curtail these developments, and the scientific community ‘promised’ never to clone a human being. But what that reminded me of are the ‘regrets’ being expressed by those physicists who created the first atomic bomb: it doesn’t stop the production of nuclear weapons till date. So basically, cloning of humans is still a possibility. Anyway, who knows whether it is already being done secretly someplace? But the ethics and legislation still keep them hidden.

However, rather than backing away completely from the idea of cloning, molecular biologists and genetists turned to cloning other ‘lesser’ living beings – animals, microorganisms and crop plants – and continue tinkering with their genomes. This led to the coining of the term Genetically Modified Organisms (GMOs), a term now synonymous with controversies in recent years. In reality, the basis of GMOs and/or genetically engineered foods is transgenesis.

Transgenesis is the process of introducing a foreign gene – called a transgene – from a different species of living organism into the genome of a different living organism, in order to increase the quantity and/or quality of such organism. While this may look weird to people and maybe a little unconventional, it has resulted into a wide variety of applications of the process including the producing pest-resistant food crops, addition of vitamins fortifications to foods such as rice for malnourished zones of the world, and particularly in understanding the function of so many genes of the human cell.

Nonetheless, there are advantages and disadvantages of these GMOs, as well as controversies. Among all these, perhaps the most overlooked point is the development of animals with human characteristics and capabilities. Emphasis has always being on the risks inherent in foods and crops produced by transgenic methods, among which include the development of carcinogens in plants, generation of hypersensitivity reaction by people who are allergic to certain substances produced in the transgenic food crops and many others.

Though I am a scientist, specifically a virologist, my own fear came when I saw the picture above.

Both rats are litter-mate; one is normal and the other, in the course of an experiment, has been transfected with the gene coding for human growth hormone TGF-beta. This was what resulted into the difference in sizes and of course the name, Muscle Mouse. My initial reaction was: Why human growth hormone? Why not any other less important hormone that potentially wouldn’t result into scary looking rats? Isn’t it possible for a transgenic female rat to give birth to baby rats of which one or more would amplify this characteristic and become bigger than its mama-rat?

My concern even grew when I compare the method used on the chimpanzees in the movie I summarized above to real life methods of transgenesis. These methods include: genetically transforming of embryonic stem cells using recombinant DNA; injection of genetic material into the pronucleus of  fertilized female gametocyte or germ cell  and; among others, the use of viruses (adenoviruses) to transfer the genetic material to the dividing stem cells. The last method is almost the exact technique employed in the Rise of the planet of the Apes! I won’t be surprised if the maker of the film knows too much of molecular biology, especially transgenesis.

What if in years to come pets are targeted as the next experimental animals in transgenesis? Maybe tomorrow you try to give your dog a bony treat you know it doesn’t like, and instead of passively refusing to eat it, the dog uses its paw to slap your hand, and with a mean irritated look on its face say something like, “Hey buster, haven’t I told you I hate this scrappy bone?” It would be a horrific amalgamation of scenes from Dr. Dollitle and chapters from the Dean Koontz’s novel, Watchers.

I read Watchers a long time ago, and while I actually loved the novel, I dismissed the plot the way I always dismiss the plot of any classic or contemporary horror novel of Dean Koontz. But maybe it is time we start paying attention to those scientific fiction stories and movies produced by the media, because now, anything might be possible with the advent of molecular biotechnology. And maybe genetic scientists and molecular biologists should also slow down a bit and think real good before they clone or modify the next available organisms.

I’m not insinuating that GMOs are evil or good – there will always be on-going debates about that by professional debaters, so why join in? –, but there is need for caution because most creations of man have always turned back to haunt him; and I don’t want to be haunted or chased by my pet dog anyway!  The reason for this slight warning is quite simple: By the time all these fictional stories start happening, we wouldn’t say we weren’t warned. Just like the caveat of the movie, 2012.