A group of genetic neuromuscular diseases that cause progressive weakness and loss of muscle mass.
In Muscular Dystrophies, abnormal gene mutations which are passed down genetically by DMD "carriers" lead to muscle degeneration. Most forms begin in childhood. It is a rare illness there are fewer than 200,000 cases in the US per year. Treatment can help, but the condition currently cannot be cured. Lab tests or imaging are required to make a medical diagnosis. There are around 40 types of Muscular Dystrophy, some are more severe than others. The most common type and the most severe is Duchenne Muscular Dystrophy, it begins at birth and mostly occurs in boys with rare cases recorded in girls. It is usually terminal.
What is Duchenne Muscular Dystrophy?
Duchenne Muscular Dystrophy is the most common and most severe form of Muscular Dystrophy and is caused by a mutation in the gene responsible for the production of the protein, Dystrophin. The Dystrophin protein is an important part of your muscles, it helps with forming and maintaining healthy muscle tissue. The lack of this protein results in fragile and easily damaged muscle tissue. Duchenne was discovered by and named after French Neurologist, Dr. Guillaume-Benjamin-Amand Duchenne, who described and detailed the illness in a young boy with the condition in his book in 1861.
DMD begins at birth and is diagnosed typically between the ages of 2 and 6, but with our advancing medical technology it can be much sooner. The DMD gene is located on the X-Chromosome so it primarily affects males with females being carriers. However, some females can, on rare occasions, be manifesting carriers which means that they can experience different degrees of physical DMD symptoms. Typically, the illness gets passed down to the child by the mother if there's a history of it in the family. But in about 25% of cases the illness can occur spontaneously even if there was no history. It is a rare disease, 1 out of 5,000 males born are affected with Duchenne with 20,000 children diagnosed every year worldwide. DMD is currently incurable.
Symptoms
Symptoms can begin as early as the age of 2 or 3. Damaged muscles become progressively weaker. The proximal muscles (the muscles close to the body's core) are affected first followed by the distal limb muscles(the muscles close to the extremities). Usually, the lower external muscles are affected before the upper external muscles. The child affected by the disease may have trouble jumping, running, and walking. They will also have enlarged calves, a waddling gait, and an inward curve of the spine. Some might also experience muscle pain. Muscle weakness, muscle loss, and permanent shortening of tendons are common in DMD. Also common are cardiomyopathy, walking on tip toes, constipation, and fatigue. In some cases, delayed development or learning disabilities can occur. Eventually, people who have the condition will need a wheelchair. Later in life, the muscles responsible for swallowing as well their cardiac and respiratory muscles will be affected. Scoliosis will result in impaired Pulmonary function and can lead to possible respiratory failure. Lifespan is often shortened by the disease. It's considered a terminal illness.
DMD Life Expectancy
Until recently, the lifespan for boys suffering from DMD was the late teens to early twenties if lucky. Due to the advancements in medical technology, specifically in Cardiac and Respiratory care, life expectancy is increasing significantly. Boys and young adults suffering from DMD are able to attend college, have careers, get in relationships, and have children. Survival into the 30s and 40s, as in my case, is becoming more and more common.
Treatments
Treatment can consists of steroids, medications, physical therapy, breathing aids(such as C-Pap machines and ventilators, or surgery may help maintain function. Proper treatment of the disease can increase the lifespan of those living with this illness and improve quality of life. Researchers are pursuing several revolutionary strategies to combat DMD such as gene therapy, exon skipping, stop codon read through(don't ask me what that means), and gene repair. Human clinical trials are currently underway.
*The Information in this blog was provided by the mda.org website with references from the sources below
* Understanding Neuromuscular Disease Care. IQVIA Institute. Parsippany, NJ. (2018).
* Ryder, S. et al. The burden, epidemiology, costs and treatment for Duchenne muscular dystrophy: An evidence review. Orphanet Journal of Rare Diseases (2017). doi:10.1186/s13023-017-0631-3
* Moat, S. J., Bradley, D. M., Salmon, R., Clarke, A. & Hartley, L. Newborn bloodspot screening for Duchenne Muscular Dystrophy: 21 years experience in Wales (UK). Eur. J. Hum. Genet. (2013). doi:10.1038/ejhg.2012.301
* Romitti, P. A. et al. Prevalence of Duchenne and Becker Muscular Dystrophies in the United. Pediatrics (2015). doi:10.1542/peds.2014-2044
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