Tracy (1990 – 1997) was a transgenically modified sheep created by scientists at Scotland's Roslin Institute to produce the human protein alpha 1-antitrypsin, a substance regarded in the 1990s as a potential pharmaceutical for the treatments of cystic fibrosis and emphysema.[1] Notably, she is the first transgenic farm mammal ever created.[2]

Alpha 1-antitrypsin comprised 50% of the total protein in Tracy's milk, a remarkably high level maintained after lactation. Similar levels were detected in the milk produced by her granddaughters.[3] A deficiency in this protein in humans can produce lung diseases, and its artificial creation was thought to be a potential success in the diseases' treatment.[2] Clinical trials for the engineered protein in 1998 revealed that it developed breathing problems in patients, and research for the milk as a remedy for the diseases has not continued since then.[4]

See also



  1. ^ "Tracy, a transgenic sheep, Scotland, 1999". Archived from the original on 2010-03-18.
  2. ^ a b "Animal Pharming: The Industrialization of Transgenic Animals" (PDF). United States Department of Agriculture. Retrieved 17 June 2014.
  3. ^ Castro, Fidel O.; Jänne, Juhani (4 October 2014). Mammary Glands Transgenesis (1998 ed.). Springer. p. 167. ISBN 978-3662033746.
  4. ^ Newton PhD, David E. (12 November 2009). DNA Technology: A Reference Handbook. ABC-CLIO. p. 25.