“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.
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).
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.
- 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.
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