Transgenic animals play an important role in the discovery and development of treatments for serious human diseases. A transgenic animal is one which has had a foreign gene introduced into its genome (Schatten 2009). This process, known as transgenesis, plays an important role in modelling human disease. In these disease models, human genes are inserted into the animal’s genome, causing them to express disease symptoms. This allows the disease pathway to be investigated, helping in the development of treatments (Margawati 2011). The significance of this technology is evident in the article I will be focusing on today, Huntington’s disease: Genetics lends a hand. This article reports the study by Yang et al., which explores the creation of a monkey model of Huntington’s disease. It explores the importance of primate models in helping to develop a cure for degenerative diseases, such as Huntington’s (Palfi & Jarraya 2008; Yang et al. 2008).
This primate model of Huntington’s disease has the potential to increase insight into this disease and assist in the development of a treatment (Palfi & Jarraya 2008). Huntington’s disease is a severe inherited neurodegenerative disorder, which is caused by a defect in the HTT gene, which is repeated (Figure 1). It results in the death of specific brain nerve cells. This disease typically results in death 10 to 15 years after onset and affects at least one person in every 10 000. There is no treatment available to slow the progression of the disease (National Institutes of Health 2012).
Figure 1: Huntington’s disease is caused by a defect in the HTT or Huntington’s gene
Source: National Institutes of Health 2012
In this study this mutated human HTT gene was inserted into unfertilised egg cells of monkeys and green fluorescent protein was also inserted, to indicate whether the transgenic procedure had been successful (Figure 2). These embryos were transferred to surrogate mothers. Of the five pregnancies which were carried to full term, three of these carried more than one copy of mutated HTT. These newborns displayed symptoms of this disease, including movement abnormalities and anatomical changes and all died within a month. The other two monkeys expressed only mild symptoms of Huntington’s, allowing the progression of this disease to continue to be studied as they age. One important finding was that the monkeys carrying a higher number of the mutated HTT, suffered an early death (Palfi & Jarraya 2008; Yang et al. 2008; Nasir 2002). The development of these models has allowed this complex genetic disorder to be better understood, and may assist in the development of a treatment for Huntington’s (Hare et al. 2008).
Figure 2: The success of the transgenic monkeys created as models of Huntington’s disease can be seen through the expression of green fluorescent protein
Source: Hare et al. 2008
This transgenic monkey model is particularly significant as it was the first transgenic primate model of a human genetic disorder (Palfi & Jarraya 2008). While non-primate transgenic models have provided valuable insight into a variety of disorders, they have significant limitations (Nasir 2002). In the case of Huntington’s disease, non-primate models do not show the behavioural features and brain changes characteristic of this disease in humans (Hare 2008). As primates have similar behavioural and neuroanatomical characteristics to humans, these models are more likely to provide insight into human physiology and diseases (Palfi & Jarraya 2008). This is clear in this study, where the primate models replicated characteristics of Huntington’s disease, similar to those seen in humans (Yang et al. 2008).
Transgenic animals play an essential role in biomedical research. This study made a significant contribution to transgenic research, in providing insight into Huntington’s disease. It could also assist in the development of primate models of other neurological disorders, such as Parkinson’s disease, helping to develop treatments for other devastating diseases (Palfi & Jarraya 2008; Yang et al. 2008).
Hare, P et al. 2008, ‘Primate model for Huntington's’, Nature biotechnology, vol. 26, no. 7, p. 777, viewed 12 March 2012,
Margawati, E 2011, Transgenic Animals: Their Benefits To Human Welfare, American Institute of Biological Sciences, viewed 14 March 2012,
Nasir, J 2002, ‘Transgenic monkey raises hope for primate models of human diseases’, Clinical Genetics, vol. 59, no. 5, pp 304-305, viewed 17 March 2012,
National Institutes of Health 2012, Huntington’s Disease, National Institute of General Medical Sciences, viewed 18 March 2012,
Palfi, S & Jarraya, B 2008, ‘Huntington’s disease: Genetics lends a hand’, Nature, vol. 453, pp. 863-864, viewed 11 March 2012,
Schatten et al. 2009, ‘Transgenic primate offspring’, Nature, vol. 459, pp. 515-516, viewed 11 March 2012,
Yang et al. 2008, ‘Towards a transgenic model of Huntington’s disease in a non-human primate’, Nature, vol. 453, pp. 863-864, viewed 12 March 2012,