Question

Once the gene that causes Huntington disease was found, researchers introduced the defective allele into mice to create an animal model of the disease. Why was this model valuable? a. It allowed the testing of potential drug therapies without endangering human patients. b. It allowed the sequencing of the mutant allele. c. It allowed the production of large quantities of the huntingtin protein. d. It allowed the study of how the gene was transmitted from parents to offspring.

Short answer

The animal model for Huntington disease was valuable because it allowed the testing of potential drug therapies without endangering human patients.

Step-by-step solution

Understand the purpose of an animal model

An animal model, like the one created for Huntington disease in mice, is a key tool for investigating the causes and potential treatments for human diseases. The model allows researchers to study the disease in a controlled environment and minimize potential harm to human patients.

Analyze each option

Now we will analyze each option given in the exercise to determine which one best shows the value of the animal model. a. It allowed the testing of potential drug therapies without endangering human patients. An animal model is especially valuable when it comes to testing potential therapies for diseases. It allows researchers to try different treatments on the animals and see which ones work before applying them to humans, minimizing potential harm to patients. This option seems like a strong contender for the right answer. b. It allowed the sequencing of the mutant allele. Sequencing a mutant allele can be done in vitro, i.e., in a test tube, using techniques such as PCR (polymerase chain reaction). It does not require an animal model. So, this option does not demonstrate the value of an animal model for Huntington disease. c. It allowed the production of large quantities of the huntingtin protein. Large quantities of the huntingtin protein can be produced in cell cultures and do not require an animal model. This option also doesn't demonstrate the value of the Huntington's disease animal model. d. It allowed the study of how the gene was transmitted from parents to offspring. While an animal model might help study gene transmission from parents to offspring, it is not the primary reason for the creation of the Huntington disease mouse model. The focus is on understanding the disease's effects and its potential treatments.

Select the correct answer

Based on the analysis in Step 2, the correct answer is (a) It allowed the testing of potential drug therapies without endangering human patients. It explains the value of creating an animal model for Huntington disease, as it allowed researchers to test potential therapies, paving the way for developing treatments for human patients.

Key concepts

Testing Drug Therapies

When discussing Huntington disease, an inherited neurodegenerative disorder, the creation of an animal model using mice was a breakthrough for medical research. Such models are essential for testing drug therapies, which is a multi-stage process aiming to determine the effectiveness and safety of potential treatments before they are prescribed to human patients.

Initially, researchers conduct in vitro tests, but these do not provide insight into how a drug behaves in a living organism. An animal model allows scientists to observe the progression of the disease and the effect of new drugs on various biological processes, such as metabolism, toxicity, and side effects. Most importantly, by using mice with the mutant Huntington gene, researchers can identify treatments that alleviate the symptoms or slow the disease's progression without putting human subjects at risk.

Once a drug shows promise in an animal model, it can proceed to clinical trials in humans, where its safety and efficacy are further evaluated. Thus, the contribution of animal models to drug testing is indispensable in advancing our fight against genetic disorders like Huntington disease.

Gene Transmission Study

Studying the gene transmission is another critical aspect of understanding genetic diseases like Huntington's. Through animal models, scientists can examine how the gene that causes the disease is passed from parents to their offspring. This is vital for predicting the likelihood of inheritance and the potential appearance of the disease in future generations.

In the context of Huntington disease, scientists are particularly interested in the patterns of autosomal dominant inheritance. What makes this disease unique is that a single copy of the defective gene, inherited from either parent, is enough to cause the disorder. By observing how the gene is transmitted in mice, researchers gain detailed insights into the hereditary mechanisms, and this knowledge is invaluable in genetic counseling and developing preventative strategies.

Moreover, crossover studies, where researchers investigate different genetic backgrounds, help determine the gene's penetrance and expressivity, which is how often or severely the disease manifests. Animal models are thus essential for understanding the complexity of genetic transmission and its implications for human heredity.

Mutant Allele Sequencing

The sequencing of a mutant allele is a vital process that unveils the precise genetic changes responsible for Huntington disease. While it's true that sequencing can technically be conducted outside an animal model, having an animal model like a mouse with the mutant Huntington gene allows for additional, context-rich research. Researchers can observe how the mutant gene behaves in an entire living organism—not just at the cellular level—and study the full spectrum of its effects.

Modern sequencing technologies, such as next-generation sequencing, have made it easier and quicker to sequence entire genomes. With a sequenced mutant allele, scientists can identify the specific mutations that cause the disease and understand how these genetic alterations lead to the symptoms seen in Huntington's disease.

This extensive genetic information aids in the development of targeted therapy approaches, such as gene editing or silencing, which could potentially correct or mitigate the effects of the defective gene. By sequencing and studying the mutant allele in an animal model, researchers can lay the groundwork for therapies that directly address the genetic root of the disease, marking a monumental step towards curing genetic disorders.