Calcium and magnesium content in fetuses at risk and prenecrotic Duchenne muscular dystrophy.

We measured calcium (Ca) and magnesium (Mg) content in muscles of fetuses at risk of Duchenne muscular dystrophy (DMD) and in a premature infant who later developed typical DMD. There was a three- to six-fold increase in muscle Ca in the fetuses and in the premature infant. In contrast to our previous reports of reduced muscle Mg in DMD children, there was an 18 to 57% increase of Mg in the fetuses at risk. Opaque and Ca-positive fibers, rarely observed in normal fetuses, were numerous in fetuses at risk and in the premature infant. No necrotic fibers were detected in the fetuses or the premature infant. These findings suggest that excessive Ca accumulation precedes necrosis in DMD. Other factors related to growth and development that occur after birth may trigger the necrosis that follows muscle Ca accumulation.