The investigators know that the muscle destruction from Duchenne muscular dystrophy (DMD) begins in infancy and we previously demonstrated that motor decline in infancy compared to typically developing infants reflects that destruction. Because of the known side effects of daily corticosteroids, most physicians do not begin treatment until age 3-5 years. Most side effects (Cushingoid faces, linear growth arrest, and bone density loss) did not happen in infants and in ambulatory boys in two separate studies. However, in infants and young boys taking (10mg/kg/week), 56% of infants and young boys did have an increase in weight percentile compared to baseline. This study will test this lower dose of prednisolone (5mg/kg/week) in an unblinded study in infants and young DMD boys (ages 1 through 30 months) to determine if equal efficacy can be achieved with fewer side effects. The primary outcome for this study will be gross motor function. The study team will enroll boys from age 1 month through 30 months and follow each for two years. We will assess gross motor function using three outcome measures: the Bayley-4 Scales of Infant and Toddler Development (Bayley-4) and the newly developed Neuromuscular Gross Motor Outcomes (GRO) and the NorthStar Ambulatory Assessment (NSAA). The one-year outcome will be the change in the Bayley-4 Scaled Score and the two-year outcome will be the change in the GRO score. This study will determine if a lower dose is equally effective and if that dose may lessen the weight gain seen in about half of the infants in the first study. Both the Bayley-4 and the GRO allow assessment of gross motor function and are feasible in all boys with DMD under the age of 42 months. In addition, the GRO allows continued assessment of motor function across a wide age span which will allow this cohort to be followed for two full years.
The hypothesis tested here is that a lower dose of intermittent oral corticosteroids (5mg/kg/week) will be equally effective to the 10mg/kg/week dose.