Why are transgenic animals engineered as models of human disease, rather than studying the disease in humans?

Question

What will be an ideal response?

Answer 1

Genomics has revealed that many human genes have identical counterparts in other organisms, including the mouse and even the fruit fly, Drosophila. More than 90% of the genes known to be involved in human diseases are also present in the mouse. This makes the mouse an excellent model to explore the genetic, biochemical, and cellular aspects of human diseases.
Mouse models of inherited human diseases have been created by transferring mutant human disease alleles into mice and using the resulting
transgenic
mice to achieve several goals: (1) to produce an animal with symptoms that mirror those in humans, (2) to use the model to study the early stages of development and progress of diseases, and (3) to test drugs to treat symptoms or, hopefully, cure the diseases.
For example, HD mice are used to study the progressive destruction of brain structures that occurs in the earliest stages of the disease process—something that is impossible to do in humans. In addition, HD mice are used to link specific changes in brain structure with behavioral changes.