Duchenne Muscular Dystrophy

genetic disorder

What is Muscular Dystrophy?

Duchenne Muscular Dystrophy is a form of muscular dystrophy that periodically gets worse with time. Muscular dystrophy is caused by a defective gene for dystrophin (a protein found in muscles). However, it often occurs in people without a known family history of the condition. It is also commonly known as a group of inherited disorders that involve muscle weakness, deterioration, and loss of muscle tissue. Each type of muscular dystrophy varies in terms of the age of the patient in which the signs and symptoms begin to show, and the sequence in which different groups of muscles are affected.

Causes:

The cause of muscular dystrophy is usually an outcome to deterioration of the body's muscles. Deterioration occurs due to the death of the body's muscle and tissue cells and soon leads to weakening of other muscles and muscle wasting.

How is it inherited?

"Each person inherits a set of genes from their father and another set from their mother. The genes have been copied from the parents' cells into the child's cells.

DMD is inherited in a pattern called 'X-linked inheritance'. The DMD gene is 'carried' by women, but does not usually cause problems in girls or women. This is because of there being two X chromosomes in women: one X chromosome has the 'faulty' DMD gene, and the other X chromosome has a normal gene, which compensates for the faulty one.

In contrast, boys with the DMD gene do not have a second X chromosome and so they cannot compensate for the faulty gene. Therefore, boys with the DMD gene always have symptoms of the disease. The DMD gene can be passed on from parent to child. For a woman who carries the DMD gene, there is a 1 in 2 chance that her sons will have DMD, and a 1 in 2 chance that her daughters will carry the gene."

http://www.patient.co.uk/health/duchenne-muscular-dystrophy

Symptoms:

Symptoms usually start appearing before age six and may appear as early as infancy. Some of these symptoms include:

  • Learning disabilities
  • Fatigue
  • Intellectual disability
  • Muscle weakness
    • Starts in the legs and progressively but less severely moves to the arms, neck, and other areas of the body
  • Difficulty with motor skills (running, hopping, jumping)
  • Frequent falls and clumsiness
  • Trouble getting up from a laying position or climbing stairs
  • Weakness quickly gets worse
  • Hard time walking
  • Breathing difficulties

Diagnosis:

Typically if a pediatrician or nurse suspects that a child may have muscular dystrophy, they more than likely begin testing the creatine kinase (CK) level in the child's blood. This enzyme, found in muscles, is abnormally high in children with muscular dystrophy. If it occurs in the child, a medical doctor usually will do a DNA testing to look for the mutations in the gene that makes dystrophin, otherwise known as an important muscle protein. If this genetic testing turns out to be negative, then a muscle biopsy may be done to confirm the diagnosis of muscular dystrophy.

Often, there is a loss of muscle mass, which may be hard to see because some types of muscular dystrophy cause a buildup of fat and connective tissue that makes the muscle appear larger.

"We have common enemies today. It's called childhood poverty. It's called cancer. It's called AIDS. It's called Parkinson's. It's called Muscular Dystrophy." John Doyle

Outlook/Prognosis:

Duchenne Muscular Dystrophy is a serious condition and unfortunately shortens life. Because the weakness of the muscles increases gradually over time, complications eventually worsen and develop. Once the muscle tissue in the limbs are all killed off, the breathing and heart problems usually become more serious. Back in the day, it was uncommon for people with DMD to live beyond the age of 20, however, improvements in treatment have made the life expectancy of a DMD infected patient to increase. In present day, the average life expectancy averages from 27 to 30 years. Although there is a lot of individual variation with the severity of the muscular dystrophy, the outlook may improve further in time with the advances in technology and treatment. The most serious complication, and the usual cause of death for people with DMD, is the respiratory complications, such as a severe chest infection at the stage when lung and heart function is really poor.

Works Consulted:

Kraft, Sy, B.A. "What Is Muscular Dystrophy? What Causes Muscular Dystrophy?"
Medical News Today. MediLexicon International, 2004. Web. 30 May 2013.
<http://www.medicalnewstoday.com/articles/187618.php>.


Unknown. "Duchenne Muscular Dystrophy." MedlinePlus. Rockville Pike, n.d. Web.
31 May 2013. <http://www.nlm.nih.gov/medlineplus/ency/article/
000705.htm>.


Kenny, Tim, Dr. "Duchenne Muscular Dystrophy." Ed. John Cox, Dr.
Patient.co.uk. Patient.co.uk, n.d. Web. 31 May 2013.
<http://www.patient.co.uk/health/duchenne-muscular-dystrophy>.

By: Jess Guglielmo