Transgenic livestock as genetic models of human disease.

Genetic models of human disease can lead to new insights concerning disease aetiology or suggest novel therapeutic interventions. Livestock species, especially pigs, cows, sheep and horses, are often good animal models of human disease. However, genetic models in livestock species have included only the study of spontaneous mutations. Production of transgenic livestock is now possible but owing to a low efficiency of production, it is very expensive and its application limited. Anticipated application of improved technologies such as embryonic stem cells and homologous recombination will allow for increased sophistication of experimental design and wider use of genetically modified livestock. In all cases, the appropriate species for a genetic model of human disease should be the species which best models the physiology of the organ or system under consideration. In the future, livestock will play an increasingly more important role in biomedical research through the application of genetic engineering methodologies.