The diagnosis process will include a thorough assessment of clinical findings and family history. Blood work is used to determine if specific enzymes are elevated, this is a key indicator toward a Duchenne diagnosis. Ideally, a Duchenne Muscular Dystrophy diagnosis would be confirmed with genetic testing or muscle biopsy.
Age at Diagnosis
The average time between when a parent or caregiver first notices symptoms of Duchenne and when the diagnosis is given is typically around two years of age. Delays in achieving developmental milestones are often seen in crawling, walking, and running.
Creatine Kinase
If Duchenne is suspected, a test can be ordered to check the creatine kinase (CK or CPK) level. Creatine kinase is an enzyme that is released by muscle as it becomes damaged. The amount of CK present in the blood of young individuals with Duchenne is likely to be significantly elevated. A normal CK level is under 200U/L. In Duchenne, it can be elevated 10 to 100 times the normal range. The CK level typically is the highest around age two and then begins to dissipate each year. It typically reaches a normal level after significant muscle tissue has been replaced by scar tissue and fat.
Genetic Testing
Genetic testing is the most reliable method used for diagnosing Duchenne. The process analyses cell DNA to find any mutations in the DMD gene. This method produces a very high rate of detecting genetic mutations. A Duchenne Muscular Dystrophy diagnosis can be made with great confidence if a mutation is discovered on the DMD gene. It can take anywhere from 4 to 6 months to get genetic test results.
Muscle Biopsy
A muscle biopsy can be done if further clarification is needed or in special cases of obtaining the level of dystrophin to determine disease severity. It is performed by removing a small amount of muscle for examination. The muscle will then be stained to view the dystrophin protein. With the modern advancement of genetic testing, muscle biopsy is usually unnecessary to confirm a diagnosis.
