Though Deflazacort and prednisone improve clinical endpoints in Duchenne 
muscular dystrophy (DMD) patients, Deflazacort produces fewer side effects. As 
mechanisms of improvement and side effect differences remain unknown, we 
evaluated effects of corticosteroid administration on gene expression in blood 
of DMD patients. Whole blood was obtained from 14 children and adolescents with 
DMD treated with corticosteroids (DMD-STEROID) and 20 DMD children and 
adolescents naïve to corticosteroids (DMD). The DMD-STEROID group was further 
subdivided into Deflazacort and prednisone groups. Affymetrix U133 Plus 2.0 
expression microarrays were used to evaluate mRNA expression. Expression of 524 
probes changed with corticosteroids, including genes in iron trafficking and the 
chondroitin sulfate biosynthesis pathway. Deflazacort compared with prednisone 
yielded 508 regulated probes, including many involved in adipose metabolism. 
These genes and pathways help explain mechanisms of efficacy and side effects of 
corticosteroids, and could provide new treatment targets for DMD and other 
neuromuscular disorders.