Duchenne Muscular Dystrophy Diagnostics: It Only Gets Better but Some of the Same Challenges Remain

Duchenne muscular dystrophy (DMD)2 is a neuromuscular disease characterized by progressive muscular weakness and degeneration of skeletal muscle. DMD is the most common X-linked recessive lethal disease, with an incidence of approximately 1 in 3500 newborns 1. Most patients are diagnosed at about 5 years of age, when their physical ability diverges markedly from that of their peers. Weakness and wasting of muscle are progressive and symmetrical, affecting the lower limbs before the upper limbs and the proximal muscles before the distal muscles 2. Affected children are usually wheelchair bound by the age of 12 years. The presence of nonprogressive cognitive impairment is also a common feature in a significant portion of DMD patients. Most patients die in their early 20s as a result of cardiac or respiratory failure.About 30 years ago my doctoral advisor, Dr. Hanns-Dieter Gruemer, decided that my thesis project would involve carrier testing for DMD using the new molecular testing. Dr. Gruemer's previous research studies had primarily dealt with membrane alterations and creatine kinase activities in DMD carriers. Although I had little molecular expertise, I am fortunate and grateful that Dr. Gruemer made this very wise thesis project decision, which also had a profound impact on my career.The molecular breakthrough that occurred at the time I started my project was that DNA probes from the short arm of the X chromosome, which recognized RFLPs linked to the dystrophin ( DMD …