1. Normal physiology and development: Transgenic animals can be specifically designed to allow the study of how genes are regulated and how they affect the normal functions of the body and its development. E.g. study of complex factors involved in growth such as insulin like factor. By introducing genes from other species that alter the formation of this factor and studying the biological effects that result information is obtained about the biological role of the factor in the body.
2.Study of disease: Many transgenic animals are designed to increase our understanding of hoe gees contribute to the development of disease. They are specifically made to serve as models for human diseases so that investigation of new treatments for diseases is made possible. Today transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s.
3. Biological products: Medicines required to treat certain human diseases can contain biological products, but such products are often expensive to make. Transgenic animals that produce useful biological products can be created by the introduction of the portion of DNA( or genes) which codes for a particular product such as human protein( -1- antitrypsin) used to treat emphysema. Similarly attempts are being made for treatment of phenylketonuria (PKU) and cystic fibrosis. In 1997, the first transgenic cow, Rosie, produced human protein-enriched milk(2.4 gma/litre). The milk contained the human alpha- lactalbumin and was nutritionally a more balanced product for human babies than natural cow milk.
4. Vaccine Safety: Transgenic mice are being developed for use in testing the safety of vaccines before they are used on humans. Transgenic mice are used to test the safety of the polio vaccine. If successful and fund to be reliable, they could replace the use of monkeys to test the safety of batches of the vaccine.