Muscular Dystrophy Breakthroughs
BACKGROUND: Muscular dystrophy is a term that describes many genetic conditions that cause muscles to waste away. The most common childhood form is called Duchenne muscular dystrophy, which is caused by the lack of a protein called dystrophin. The disease first presents itself with generalized weakness and muscle wasting of the hips, pelvic area, thighs and shoulders. "The child may not be meeting their developmental milestones -- not walking on time, falling, tripping, unable to climb stairs," Linda Cripe, M.D., a pediatric cardiologist at Cincinnati Children's Hospital Medical Center in Cincinnati, Ohio, told Ivanhoe. Eventually, the condition affects all voluntary muscles, including the heart and lungs. It's rare for a patient with Duchenne muscular dystrophy to survive past the early 30s, according to the Muscular Dystrophy Association. The condition primarily affects boys, who inherit it from their mothers. Women who are carriers of the condition usually show no symptoms.
Duchenne muscular dystrophy becomes deadly when it spreads to the heart and breathing muscles. "The majority of the children will die as a result of either respiratory complications -- because it affects the muscle that help the child breathe -- or they will die as a results of the failure of the heart muscle to perform adequately," Dr. Cripe said. Because earlier detection leads to earlier treatment of the condition, Dr. Cripe says it's critical to diagnose a child with the condition as early as possible. "The only way that we have to treat this disease at this moment in time is by jumping on the symptoms as soon as possible and addressing them early in order to try to maximize the patient's quality and quantity of life," she said. Dr. Cripe says science is making progress in the area of detecting respiratory and cardiac complications earlier, and thus extending the lives of patients with Duchenne muscular dystrophy. At Cincinnati Children's Hospital Medical Center, she is using cardiac MRI to track the development of damage to the heart of patients with the condition. "As a result of that, we can institute traditional heart failure treatments earlier," Dr. Cripe said.
TREATMENTS: Treatments for heart damage caused by Duchenne muscular dystrophy include ACE inhibitors, diuretics and beta blockers -- all used in the treatment of traditional heart failure. "A lot of these things that you would use in 65-year-old men, you're using in 12-year-old kids," Dr. Cripe said. For treatment of lung damage, some doctors prescribe cyclosporin A (CsA), but it carries the side effect of weakening the immune system. One new drug being investigated in the treatment of lung damage in children provides an alternative to such drugs. Called Debio 025, the drug was shown in a recent study in mice to protect against muscle wasting. More importantly, the drug didn't affect calcineurin, a protein important to maintaining a healthy immune system.