Quantitative real time PCR: Two micrograms of RNA was reverse transcribed using a High Capacity cDNA Synthesis kit (Applied Biosystems, Branchburg, NJ). Exon skipping qPCR was performed using Syber green Kits (Applied Biosystems), primer sets (IDT) and the StepOne Plus Real-Time PCR system (Applied Biosystems). Primer sets used were as follows: total dystrophin transcripts, ex19-20: Fwd: GCCATAG-CACGAGAAAAAGC, Rev: GCATTAACACCCTCATTTGC; Delta23 dmd transcript, Fwd: GCG CTA TCA GGA GAC AAT GAG, Rev: GTT TTT ATG TGA TTC TGT AAT TTC CC.