Therefore elevated levels of creatine kinase can be detected from a blood test and it is a measure of muscle damage. During the process of muscle degeneration or breakdown, the muscle cells are broken open and their contents find their way to the bloodstream. Creatine kinase is an enzyme that is present normally in high concentrations in the muscle cells of our body. However, the results of genetic testing may not be conclusive of a diagnosis of DMD, and only the muscle biopsy can tell the level of dystrophin protein for sure.įor the remaining individuals, a combination of clinical findings, family history, blood creatine kinase concentration and muscle biopsy with dystrophin studies confirms the diagnosis.
Those individuals who are not found to have a detected change in the DMD gene using this method, and who are diagnosed with DMD by biopsy, still have a change in their gene but it is in areas of the gene that are not examined using these methods. Together these two methods can detect the disease causing changes in about 95% of patients. Genetic testing is constantly changing, but the methods currently being used look for large changes in the gene ( deletion/duplication) and another method, which looks at the letters that spell out the instructions found within the DMD gene ( sequencing). Genetic testing (looking at the body's genetic instructions) on a blood sample for changes in the DMD gene can help establish the diagnosis of Duchenne muscular dystrophy without performing a muscle biopsy. Often these boys are classified as having Becker muscular dystrophy. Some individuals can be found to have an intermediate amount of the dystrophin protein. A boy with Duchenne, on the other hand, will have an absence of dystrophin and appear to have an absence of the caulking around the muscle cells. A muscle which has average amounts of dystrophin will appear with the staining technique as though there is caulking around the individual muscles cells and it is holding them together like window panes. The dystrophin protein can be visualized by staining the muscle sample with a special dye that allows you to see the dystrophin protein. If untreated, the affected boys become wheelchair dependent before age 13 years.Ī muscle biopsy (taking a sample of muscle) for dystrophin studies can be done to look for abnormal levels of dystrophin in the muscle. The symptoms present before age 5 years, and they often have extremely elevated creatine kinase blood levels (which are described below). A clinical diagnosis may be made when a boy has progressive symmetrical muscle weakness. Breathing complications and cardiomyopathy are common causes of death.ĭuchenne muscular dystrophy is diagnosed in several ways. Intellectual impairment may occur, but it is not inevitable and does not worsen as the disorder progresses.įew individuals with DMD live beyond their 30s. Cardiomyopathy (enlarged heart) occurs in almost all cases, beginning in the early teens in some, and in all after the age of 18 years. Muscular weakness and skeletal deformities frequently contribute to breathing disorders. Bones develop abnormally, causing skeletal deformities of the spine and other areas.
By age 10, braces may be required for walking, and by age 12, most boys are confined to a wheelchair. There is a steady decline in muscle strength between the ages of 6 and 11 years. Symptoms usually appear in boys aged 1 to 6. Occasionally, there can be pain in the calves. Muscle contractures occur in the legs, making the muscles unusable because the muscle fibers shorten and fibrosis occurs in connective tissue. Muscle weakness also occurs in the arms, neck, and other areas, but not as severely or as early as in the lower half of the body.Ĭalf muscles initially enlarge and the enlarged muscle tissue is eventually replaced with fat and connective tissue (pseudohypertrophy). This muscle weakness causes a waddling gait and difficulty climbing stairs. There is progressive muscle weakness of the legs and pelvic muscles, which is associated with a loss of muscle mass (wasting). The mean age for walking in boys with Duchenne muscular dystrophy is 18 months. Typically, the first noticeable symptom is delay of motor milestones, including sitting and standing independently. The symptoms usually appear before age 6 and may appear as early as infancy.
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