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"Human 'Knockouts' May Reveal Why Some Drugs Fail":

From studying people who have more than 1,300 knocked out genes, scientists can confirm that a new drug should be efficient in treating medical issues. (2.5)

What is a Gene Knockout?

Genes are the working subunits of deoxyribonucleic acid (DNA). DNA contains the instructions needed for an organism to develop, survive, and reproduce. An organism's genes are made up of short segments of DNA; these genes provide information regarding how an organism's cells should function and what traits are present in an organism. As human beings, our genes are passed down from our parents, which explains why we possess similar characteristics to them such as hair color, freckles, etc. While physical features are often passed down from parent to offspring through genes, we can also inherit different types of diseases from our parents. (2.4)

Watch this video to learn more about what genes are and the roles that they play in organisms.

So what exactly is gene knockout? A gene knockout is "a genetic technique in which one of an organism's genes is made inoperative." Gene knockout can also refer to an organism that lacks a gene; these organisms are called "knockout organisms." On the other hand, a gene knockin is just about the opposite of a gene knockout; it involves the substitution of one gene with another, rather than completely deleting the gene in an organism. (2.1)

Gene Knockout Research Discoveries

Why should gene knockouts matter to us? Using gene knockouts, scientists and researchers can potentially alter the different types of diseases that human beings and other organisms are prone to. Hover and click on the images below to learn about a few studies that have been conducted to test the effect of gene knockouts on different diseases and illnesses in organisms.

The DYRK1A gene is known to be correlated with Down syndrome. To test their hypothesis that under expression of this gene is linked to autism, researchers knocked out this gene in zebrafish. They discovered that knocking out the DYRK1A gene is not directly linked to autism, however, the zebrafish did demonstrate autism-like symptoms.

Gene Knockout in Zebrafish Leads to Autism-like Behaviors

Scientists at Johns Hopkins Bloomberg School of Public Health have used the CRISPR tool to delete a single gene from mosquitoes. They have discovered that this one gene deletion can make mosquitoes highly resistant to malaria parasites. As a result, mosquitoes will be less likely to transmit malaria parasites to humans.

Gene Knockout Makes Mosquitoes Highly Resistant to Malaria Parasite

Reduced levels of the enzyme BACE1 results in less formation of brain plaque, ultimately decreasing the chances of having Alzheimer's Disease. Knocking out a crucial gene in mice yielded less production of the enzyme BACE1 as they aged. Instead of developing Alzheimer's disease like they originally should have, these mice remained healthy as they aged due to the removal of a crucial gene.

Mice Provide Evidence That Alzheimer's Disease Can Be Reversed With Just One Enzyme

Why are Gene Knockouts Important?

During the year of 1989, Mario R. Capecchi developed the gene knockout technique in order to explore the functions of a newly identified gene. Ever since his development, over 4,000 genes have been knocked out of the mouse genome. These "knockout mice" are used to study gene functions that correspond to the genes found in the human genome, which contains at least 30,000 different genes. Gene knockout technology is a necessary tool for understanding human development and identifying the genes that are responsible for human diseases. Gene knockout can potentially be used in order to prevent passing down disorders and diseases from parents to offspring. (2.2), (2.3)

Challenges With Gene Knockout

As researchers and scientists are developing reliable and efficient methods for conducting gene knockout technologies, they are faced with many challenges. Some of the challenges for developing these technologies can be due to the vast amount of money needed to carry out research and experiments, and due to the difficulties in finding reliable test subjects to conduct these experiments on. Otherwise, successfully using gene knockout will rely on precision and accuracy. Scientists can easily knock out a wrong gene, causing potential health problems for patients or test subjects. Therefore, it is crucial to avoid mistakes and target the correct gene for the success of this technology, or for any gene technology in general. Additionally, with the use of gene technology comes various risks; different organisms and patients respond differently to gene alternations. For example, some people's bodies will develop an unwelcome immune response to a gene knock out, which could cause serious illness or even death. (2.8)

Another challenge that scientists and researchers face are gene therapy patents. Whether gene therapy patents are conferring rights for gene therapies or preventing the use of them, there are not many patents that have been authorized. In addition, the number of authorized gene therapy patents have declined over the last decade (as shown in the figure below). Without an authorized patent, scientists and researchers do not have legal rights to conduct or test gene therapies such as gene knockouts. (2.11)

Despite these challenges, scientists and researchers hope to accomplish a variety of goals once gene knockout technologies have been proven reliable and efficient. Some of these goals include the ability to study the complexity of gene regulations and their functions, potentially cure cancerous and genetic disorders, understand how human development works by studying human embryos, and to alter phenotypes. (2.9), (2.10)

How Do Gene Knockouts Work?

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