Standing up from a chair, climbing stairs, brushing one’s hair – all can be a struggle for people with a rare form of muscular dystrophy that causes progressive weakness in the shoulders and hips. Over time, many such people lose the ability to walk or to lift their arms above their heads.
This form of the disease – called limb girdle muscular dystrophy – affects a few thousand people nationwide. Like other rare illnesses, it tends not to attract much attention from researchers and funding agencies, so progress toward developing therapies has been slow. But a team at Washington University School of Medicine in St. Louis that identified a subtype of the disease in 2012 has shown that lithium improves muscle size and strength in mice with this form of muscular dystrophy. The findings, published April 18 in Neurology Genetics, could lead to a drug for the disabling condition.
“There are no medications available for people with limb girdle muscular dystrophy, so we are very excited to have a good therapeutic target and a potential therapy,” said senior author C. Chris Weihl, MD, PhD, a professor of neurology who treats people with muscular dystrophy at the university’s Neuromuscular Disease Center. “This has been an amazing project. It all began when we diagnosed a patient with muscular dystrophy of unknown cause. Genetic sequencing then helped us identify a new subtype, and we’ve been able to take that all the way through to a possible therapy.”
Limb girdle muscular dystrophy can be caused by variations in any one of more than a dozen different genes. Several years ago, Weihl and colleagues – including neurologists Robert Baloh, MD, PhD, and Matthew Harms, MD – identified two families in which several members had symptoms of the condition but none of the known genetic variants. By analyzing the DNA of affected and unaffected members of both families, the researchers found that a variation in the gene DNAJB6was responsible for their muscle weakness.