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How can animals be genetically engineered to produce useful proteins in their milk?

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DNA extraction and recombinant DNA technology — recombinant DNA The process of DNA extraction is necessary to isolate molecules of DNA from cells or tissues. A series of steps, including the use of protease enzymes to strip proteins from the DNA, are required for isolating pure DNA that is suitable for use in later procedures, such as cloning or sequencing.

To engineer animals to produce useful proteins in their milk, scientists use recombinant DNA technology to introduce a specific human gene into the genome of an animal, such as a sheep or goat. This process is a form of pharming, where the animal is modified so that the desired protein is secreted directly into its milk.12

The procedure typically involves:
* Genetic Modification: Scientists insert the target gene—which encodes a therapeutic substance like human factor IX or alpha-1 antitrypsin—into a zygote or cell nucleus.2
* Expression: The animal is engineered to express this gene specifically within the mammary glands, ensuring the protein is secreted into the milk.12
* Harvesting: Once the animal matures and produces milk, the therapeutic protein is isolated and purified from the milk for medical use.12

This method allows for the scalable production of complex pharmaceuticals, such as ATryn, which is used to prevent blood clots. While highly effective, the practice remains subject to rigorous safety testing to ensure the final product is free of pathogens.2