“Fishing” for Clues to the Cause of CHD

Because the definite cause of CHD cannot always be identified, mothers often feel guilt over the possibility that they harmed their child in the womb. [Photo: Staff Illustrator]

Because the definite cause of CHD cannot always be identified, mothers often feel guilt over the possibility that they harmed their child in the womb.
[Photo: Staff Illustrator]

“Honey, it’s not your fault!” The young husband tried to console his wife, who was weeping as she folded and refolded the multi-colored baby blanket on her lap. The new parents had just received devastating news: Their beautiful baby was born with a heart abnormality called Congenital Heart Disease (CHD).  They had just confirmed that tiny Sophia had all her fingers and toes when she was whisked away to the operating room.

The frantic mother was not alone in wondering if she could have done something to have prevented this abnormality. Since there is no identifiable cause of CHD, much of the burden is placed on the mother, who is often left feeling that she harmed her child during her pregnancy (Lucile Packard Children’s Hospital, 2013). The fact is CHD is the most common birth defect in the United States and approximately 35,000 American babies are born with Congenital Heart Disease (CHD) each year (Phoenix Children’s Hospital, 2012).

CHD is an abnormality that results from the heart or blood vessels near the heart not developing properly before birth. It can be fatal, but if treated properly and within the correct time frame, it can be corrected through medication or surgery (Mayo Clinic Staff, 2011).

In order to lift some of the burden off the mother’s shoulders, and to answer the questions surrounding CHD, scientists have recently been using Danio rerio, more commonly known as the zebrafish, as a model to study the condition.  This research allows for the analysis of the development of CHD on a cellular level, so that more effective therapies can be developed.

Zebrafish models may reveal new information about the causes of Congenital Heart Disease. [Photo: “Two Zebrafish Swimming in a Tank” by Novartis AG; License: CC BY-NC-ND 2.0]

What is Congenital Heart Disease?

CHD is a condition present at birth. It affects the structure of a baby’s heart and how it functions, changing the way blood flows through the heart and out to the rest of the body. CHD scales from very mild to very severe, and is treated accordingly through medication, surgery, or a combination of both. (Cambridge Student Journal of Genetics, 2013).  Out of every 1,000 births, six babies are diagnosed with CHD. The causes of CHD are so vast that doctors can have difficulty determining the exact cause in certain cases.  Some cases are caused by a single defective gene, while other cases can result from a combination of genetic and environmental factors.  For instance, CHD can be a symptom of fetal alcohol syndrome.

Mutations of multiple genes that affect common developmental pathways have been found to be associated with CHD.  These mutations can cause malformed valves and aortas. Despite what scientists do know about CHD, the disease is far from fully understood, creating a need for accessible animal models (Cambridge Student Journal of Genetics, 2013).

Comparison between normal heart and a CHD patient’s heart [Photo: National Institute of Health]

Zebrafish are small tropical fish that have become a favored animal model in the study of gene function during embryonic development. Zebrafish embryos are completely transparent, making them ideal for studying developmental processes as they occur and allowing for direct visualization of developing organs, such as the heart (University College of London, 2011).   Embryos are fertilized and complete development externally, making them accessible at every stage of development, unlike mammalian models.

The zebrafish model is crucial to gene discovery, allowing scientists to uncover important clues about the function of candidate genes (University College of London, 2011). Because they reproduce rapidly and have very high reproduction rates, researchers have access to multiple generations and a large number of fish. Additionally, exceptional tools exist for genetic manipulation of zebrafish, making them ideal for developing gene therapies (University College of London, 2011).

Without a doubt, this new and successful animal model holds much hope for future CHD research.   The mother once living in fear that she harmed her child during pregnancy can now be at ease knowing that the zebrafish could potentially unlock answers to the mysteries of CHD.

Zebrafish embryo [Photo: National Human Genome Research Institute]

Zebrafish embryo
[Photo: National Human Genome Research Institute]

In Brief

  • Congenital Heart Disease (CHD) is a heart abnormality that affects 35,000 American babies each year
  • Symptoms: abnormal heart rhythms, a bluish tint to the skin, shortness of breath, rapid fatigue upon exertion, dizziness or fainting, and swelling of tissue or organs
  • The zebrafish is the ideal animal model for CHD due to its transparent skin, accessible transparent embryos, and ability to reproduce readily and develop embryos quickly
  • There are many existing tools for the genetic manipulation of zebrafish, aiding in the development of gene therapies for the treatment of CHD
  • The use of zebrafish is still in early stages, but this model has the potential to aid in the discovery of treatments or even a cure for those with CHD.

Works Cited

This article was written by cYw19. As always, before leaving a response to this article please view our Rules of Conduct. Thanks! -cYw Editorial Staff

A researcher examines zebrafish embryos under the microscope [Photo: National Human Genome Research Institute]

A researcher examines zebrafish embryos under the microscope
[Photo: National Human Genome Research Institute]


Author: cYw19

Hello cYw visitors! I am a sophomore in high school and this is my first year being a part of curiousYOUNGwriters.  It has been a great experience so far, as I have learned so much about topics I never even knew existed prior to this experience.  The cYw blog allowed me to use my prior knowledge on good writing skills and also to learn about many new topics in science today.  When I am older, I aspire to be a pediatric oncologist, so this experience has allowed me to expand my knowledge in current medical research, a field I aspire to become an expert in.  I have always had a passion for science, and curiousYOUNGwriter has allowed me to express this passion through wonderful articles about various topics in current science research.  Aside from science, I am a competitive gymnast, high school cheerleader, dancer, musician, and track runner.  I hope you enjoy our articles and find them both captivating and educational!

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  1. Avatar

    What an excellent presentation on CHD! My youngest granddaughter was born with Truncus Arteriosis. My daughter was unaware of any problems as she had an ultrasound the day before the birth. The 2nd time she nursed she went into cardiac arrest. What a shock it was to learn that she had a major heart defect! She has had 3 open heart surgeries (the first at 3 days old & a 10% of survival) and is now 15! She’s our miracle child. She participates in cheer leading and has danced since she was 3!!
    I very much appreciate your efforts to bring awareness of CHD.
    Best wishes in your future endeavors, it looks like you’re well on your way to a bright future!
    Lee Anne Schery

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    • Avatar

      Hello Ms. Schery,
      I am very glad you enjoyed my article. Your daughter’s story is truly inspirational and I am happy to hear that she is doing well. I have enjoyed researching and writing about CHD very much and hope that my article will raise awareness about the topic. Best Wishes to you and your daughter.
      cYw 19

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    • Avatar

      Hi Ms. Schery,
      I am very glad that you enjoyed my article. Your daughter’s story is truly inspirational and I am very happy to hear of her success in cheerleading and dance. I hope to continue to raise awareness about CHD and inform people about it. Best wishes in the future to you and your daughter.
      cYw 19

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    This is really interesting seeing science deviate from the usual animals they use: rats, rabbits, etc. and use zebrafish instead. Espially because now scientists can look at a lot more of them, and draw better conclusions. I wonder how they will recognize CHD in zebra fish. Since, they are much smaller, and maybe the chances of them suffering from this disorder are a lot lower than in humans, thus they can’t study as many cases as anticipated.

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