1. Physical Symptoms
A physical examination by a doctor is often the first step toward diagnosing muscular dystrophy (MD) and identifying which specific type of the progressive disease you or your child has. The doctor will take a detailed family history and observe you or your child to see which areas of the body are most affected by muscle weakness. Most forms of MD, including Duchenne, Becker and Myotonic muscular dystrophy (also called Steinert's disease), primarily affect the limbs and respiratory systems. If your physician suspects your child has Duchenne muscular dystrophy (DMD), he will examine your youngster's calves to look for an enlargement that is a common symptom of DMD. Older children who display more of a muscle weakness in their pelvis, back and shoulders than their legs may be diagnosed with Limb-Girdle MD, a relatively slow-progressing form of the disease. The symptoms of Limb-Girdle can vary widely in terms of severity. It's possible that one person with this type of MD will display only a minor muscle weakness throughout his life, while another may eventually need to use a wheelchair for mobility.
Your limbs are not the only area of your body that can be affected when you have MD. If you notice your main difficulties are with smiling, drinking from a straw or otherwise using your facial muscles, your doctor may diagnose you with facioscapulohumeral muscular dystrophy (FSHD). The main weaknesses in people with FSHD are in the face, shoulders and upper arms.
2. Age of Onset
The age of onset will help doctors determine the form of MD. Duchenne is the most common and most severe form of MD and is usually diagnosed at a very early age compared to other types of the disorder. DMD affects mostly boys, with symptoms beginning as early as age two. Limb-girdle MD tends to manifest itself in the "tween" years, from eight to 15 years of age. People who have Becker, Steinert's or FSHD do not usually display signs of the disease until they are teenagers or even young adults in their 20s.
3. Results of Lab Work
The most definitive way to identify the particular type of muscular dystrophy is to talk to your doctor about the results of your lab tests. Your doctor will have ordered blood tests and possibly muscle biopsies as part of the diagnostic process.
Tests showing a lack of dystrophin point to either the Duchenne or Becker forms of MD. Dystrophin is a protein that gives muscles their shape and length. If your body doesn't produce enough of it, your muscles deteriorate.
DNA tests may show abnormalities in some of your genes. If a particular gene is bigger than it should be, you may have Myotonic MD. FSHD, on the other hand, is caused by a mutation of chromosome 4 that causes the DNA to be shorter than normal.
