Duchenne muscular dystrophy (DMD) is a rare disease that is characterised by a rapid progression of muscle degeneration that eventually leads to death. The incidence of DMD in males is one in 3000 births. Whilst it is caused by an X linked gene carried by females, it is inherited almost exclusively by males. Symptoms of this disease appear when the patient is three to five years old. At twelve years the patient can become wheelchair-bound until they die at 20 to 30 years old ago. Since there are no effective treatments available, new therapies that are based on animal models are under investigation. Once such model is the golden retriever muscular dystrophy (GRMD) canine model. GRMD in dogs generates similar clinical signs to human patients with DMD. This is because these dogs carry the same mutation in their genes that is also seen in some DMD patients.
In 2002 a GRMD kennel was established to enable a greater understanding into DMD in humans. Fifteen dogs were closely observed from birth which enabled the researches to identify three different phenotypes. These were classified as mild, moderate and severe. The individual status of each dog was confirmed by polymerase chain reaction analysis and genotyping. The observations from each group differed as results overall showed that the classification (mild, moderate or severe) of the phenotypes reflected the severity with which the dogs displayed clinical symptoms of GRMD.
This variability in how each dog was affected by the disease is similar to that of DMD patients. It was discovered that this cannot be attributed to genetic factors, but it may be due to a correlation between the amount of dystrophin and the severity of the phenotype. It is suggested that an increase in some proteins, which are involved in cell cycle regulation, may be associated with a milder phenotype. This discovery may bring scientists one step closer in determining an effective treatment for patients suffering with DMD.
By Caitlin See
42011190
References:
Article: Ambrosio, C.E., Fadel, L., et al (2009). Identification of thee distinguishable phenotypes in golden retriever muscular dystrophy Genetics and Molecular Research, 8, 389-396.
Image: Fox News, (2006). “Stem Cell Treatment Cures Muscular Dystrophy in Dogs” http://www.foxnews.com/story/0,2933,229745,00.html Accessed
