Golden Retrievers: Man’s Best Solution for Duchenne Muscular Dystrophy

Where It Began

At the tender age of two, John experienced the first signs of abnormality. Having just learned how to walk the past day, he began to feel weak, experiencing a pervasive sense of fragility that spread slowly through his legs until he eventually forgot how to walk.

When his parents enrolled him in school, he found it difficult to memorize all those foreign symbols and abstruse operations. “Repeat ‘A, B, C’ after me”; “Add the 7 and carry the 1,” his teachers said, but all he heard was “gobbledygook.”

Men in white jackets carrying strange instruments came and went, always tapping his knee and looking at him with sad eyes. As each one shook his head and walked out the door, the hopeful smiles on his parents’ faces withered into despondent grimaces, and John wondered what he had done wrong.

Then came the day that John met Dr. Duchenne. John liked him; he was the first one to light up his parents’ faces, even though when he cut out a piece of John’s muscle it hurt him very much. He came to visit him more after that, and the other jacketed men disappeared. But even Duchenne, with his revolutionary muscle biopsy and original ideas, couldn’t save John in time.

John was the first that French physician Guillaume-Benjamin-Amand Duchenne
encountered in a long string of patients all exhibiting the same mysterious symptoms.
Each would start experiencing muscle weakness at a young age, have trouble learning,
and continue to worsen until confined to a wheelchair. Death usually occurred around
age 25 due to defective lung muscles.

Despite never discovering a cause or treatment for the illness, Duchenne was the first
to provide a detailed description of its symptoms and progression (Jay), earning him the condition’s name. Today we know this disease as Duchenne muscular dystrophy (DMD).

NormalMuscleTissue

Normal Muscle Tissue

 

DystrophinMuscleTissue

Tissue Affected By Muscular Dystrophy

 

Since then, the cause of DMD, a degenerative disorder that affects nearly 1 in 3,500 male babies, has been attributed to a lack of dystrophin protein (Kerkis). That is not to say, however, that females cannot be affected, too. Due to the dystrophin gene’s location on the X chromosome, males, who need only one copy of the gene to contract DMD, are twice as likely to be diagnosed with it as females (Darras).

Despite valiant efforts, no cure for DMD currently exists. Scientists now think that hope may lie within a common friend – the golden retriever.

And Then There Was Hope

Golden retrievers are popular among families for their affectionate demeanor, but are more well-known among scientists for their genetic code.

Golden Retriever

In 1988, Dr. Beth A. Valentine and her collaborators at the Cornell University College of Veterinary Medicine studied a group of dogs suffering from a degenerative disease, coined golden retriever muscular dystrophy (GRMD), which physically resembled DMD. The dogs, like human DMD patients, lacked dystrophin protein and exhibited muscle weakness and gait abnormalities, suggesting similarity between GRMD and DMD (Valentine).

The scientists were excited by this idea, and for good reason. Homology of a physical feature between different animals indicates that the feature stemmed from a common evolutionary ancestor. As a result, the species possessing the homologous features may have similar genetic codes.

Scientists thought that if GRMD and DMD had similar enough genetic coding, then the golden retriever would have the potential to become an excellent animal model for further study of DMD (Kornegay).

To confirm this hunch, scientists led by Dr. N.J.H. Sharp of the Duke University Medical Center extracted the dystrophin gene from both normal dogs and GRMD- inflicted dogs.

After analyzing these genes, Sharp’s research team found that the defective gene (with GRMD) was shorter than the normal gene, leading them to believe that GRMD could be caused by genetic deletions. The scientists then compared these genes to human DMD patients’ dystrophin genes, and what they found proved groundbreaking:

Some of the same genetic mutations occurred in human DMD patients as in the GRMD dogs (Sharp).

Following up on Sharp’s discoveries, Dr. Richard J. Bartlett of the University of Miami School of Medicine and his collaborators used a gene repair technique to promote cellular repair of the dystrophin gene in a six-week-old male dog. Their efforts cumulated with the dog producing complete dystrophin proteins on its own for up to 11 months (Bartlett et al).

What’s Next?

Scientists are hopeful that this treatment will eventually be extended to human patients, though the journey ahead seems far from smooth.

Since the technique uses short synthesized DNA segments, an extraordinarily large dose of these must be delivered into the muscle in order for the treatment to be effective. In addition, too many different types of dystrophin mutations exist for the treatment to be generalized.

Realistically speaking, a cure for DMD is still many years from being approved by the Food and Drug Administration, but animal models such as the golden retriever provide scientists with an excellent method of safely investigating the disease without risking accuracy.

For now the golden retriever remains man’s best friend, but one day in the near future it may be known to us as the incredible animal behind the DMD cure.

In Brief:

  • Duchenne muscular dystrophy (DMD) causes muscle weakness and learning disabilities at a young age in about 1/3,500 male babies.
  • DMD is caused by a lack of dystrophin protein.
  • There is no cure yet for DMD.
  • Golden retrievers can contract DMD, possibly leading to a cure for this illness (complete dystrophin proteins have already been produced in male retrievers).

Works Cited

This article was written by cYw3. As always, before leaving a response to this article please view our Rules of Conduct. Thanks! -cYw Editorial Staff

 

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This entry was posted in cYw 2012 and tagged , , , by thereadingzone. Bookmark the permalink.

About thereadingzone

A current high school English teacher (and former middle-grades Language Arts teacher), I enjoy reviewing middle-grade and YA books. I review recently published books that I purchase or that are sent to me. (I do not review every book). I also love to share experiences I have in my reading and writing workshop. I read and write daily with my students and sometimes learn as much from them as they learn from me!

15 thoughts on “Golden Retrievers: Man’s Best Solution for Duchenne Muscular Dystrophy

  1. My niece has MD, so I have a personal interest in how research in this area advances. Beyond that, I found that this article has all the hallmarks of excellent science writing – a good story, a clear, non-technical explanation of the scientific challenge, and description of the contribution that an animal model can make to finding a cure. Congratulations to the writer – this is the kind of clear, compelling science communication we need more of to increase public understanding of the importance of medical research. I hope you continue to develop your talent in this area.

  2. Fantastic post! What a great idea to have pre-collegiate students write about how animals are helping find cures and treatments for diseases and conditions that affect humans and animals! Golden’s are an amazing breed!

  3. Wow that’s so cool! Can the technique for DNA repair that they used on the Golden Retrievers work sucessfully on humans as well?

  4. This article is wonderful and touching in many ways, I’m so glad to see that there are young people who are so enthusiastic about writing and science. Keep up the amazing work, I’m positive I’ll be back for the subsequent articles.

  5. This was a very interesting article and I am continually amazed by the work that can be done with animals that benefits humans as well! In addition, this is an incredible blog and I look forward to reading more articles.

  6. I found this article to be ecxtrmely intresting and very well written. This article makes me remember that all living things are connected form the habitat we live in, to food chains, to common ancestors. I also like how you privided diagrams for the reader to see how DMD effects muscle.

  7. That was a very interesting article. I did not know that GRMD could be utilized for research for DMD. How far away could a cure for DMD be? Are there any other breeds of dogs that have a similar genetic makeup that could be used for DMD research?

  8. Great post! Very clear writing.

    Unfortunately there are still a lot of obstacles in gene therapy as it is not easy to get the gene to the target tissue in the right amount without disrupting the host’s genes. One of the most famous success stories of gene therapy is Leber Congenital Amaurosis (blindness), first tested on Briard dogs who have the same mutation.

    http://www.nei.nih.gov/lca/nei_timeline/

  9. It’s surprising to find out, once again, how closely linked we humans are to all of the other organisms on the planet. If the scientists behind the research of DMD can find a cure within the Golden Retriever’s DNA, then it will certainly be another breakthrough for geneticists. I wonder how many girls it affects, though. Would the treatment have to be different for them since they only have one X chromosome? And how are the tests being done? Are the animals in pain? Also, how would the treatment occur for a human baby?

  10. Your introduction was very well written. It really gives the reader an understanding of how devastating DMD can be. The research that is being done is incredible. I was intrigued by the gene repair technique that you mentioned. I’d be very interested in learning more about how that works. You mentioned that after eleven months that the golden retriever was able to produce the dystrophin proteins on its own; I’m curious if this was recreated in more than one dog. I also wonder if the sequence for this gene is the same for all species or individual. Overall, great job on writing a very informative article.

  11. I thought that this blog was very well written. The introduction hooked me in and it caught my attention how touching this subject was. It’s amazing how much we use animals to research diseases. Hopefully one day this treatment will be able to work on humans.

  12. I Like your blog overall. It was very interesting how they are taking the genes from a mans best friends. The blog was thorough, and I liked the information given. When do you think these new treatments will be able to hit the market? Do you think anytime soon, and how effective do you think it will be?

  13. Good job on this post. It was very informative and I was able to learn more about DMD. Its amazing how “man’s best friend” can be more than a best freind but also a savior.Do you think that some time soon they will have a cure?

  14. I liked how you opened with a story. I also liked how you cleverly told us the history behind how the name was given to the disorder. I know DMD effects muscles and ones overall health (as the BrainPOP hyperlink video said) but how does that effect one’s mental capabilities? Also is there a way to grow out DMD? Can one’s muscles suddenly grow strength, or once a patient is diagnosed there is no currently known way to help them?

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