Background: Duchenne muscular dystrophy (DMD) is a devastating X-linked$nrecessive genetic myopathy. DMD physiopathology is still not fully$nunderstood and a prenatal onset is suspected but difficult to address.$nMethods: The bone morphogenetic protein 4 (BMP4) is a critical signaling$nmolecule involved in mesoderm commitment. Human induced pluripotent stem$ncells (hiPSCs) from DMD and healthy individuals and human embryonic$nstern cells (hESCs) treated with BMP4 allowed us to model the early$nsteps of myogenesis in normal and DMD contexts.$nResults: Unexpectedly, 72h following BMP4 treatment, a new long DMD$ntranscript was detected in all tested hiPSCs and hESCs, at levels$nsimilar to that found in adult skeletal muscle. This novel transcript$nnamed ``Dp412e'' has a specific untranslated first exon which is$nconserved only in a sub group of anthropoids including human. The$ncorresponding novel dystrophin protein of 412-kiloDalton (kDa),$ncharacterized by an N-terminal-truncated actin binding domain, was$ndetected in normal BMP4-treated hiPSCs/hESCs and in embryoid bodies.$nFinally, using a phosphorodiamidate morpholino oligomer (PMO) targeting$nthe DA/ID exon 53, we demonstrated the feasibility of exon skipping$nvalidation with this BMP4-inducible hiPSCs model.$nConclusions: In this study, the use of hiPSCs to analyze early phases of$nhuman development in normal and DMD contexts has led to the discovery of$nan embryonic 412 kDa dystrophin isoform. Deciphering the regulation$nprocess(es) and the function(s) associated to this new isoform can$ncontribute to a better understanding of the DMD physiopathology and$npotential developmental defects. Moreover, the simple and robust$nBMP4-inducible model highlighted here, providing large amount of a long$nDMD transcript and the corresponding protein in only 3 days, is already$nwell adapted to high throughput and high content screening approaches.$nTherefore, availability of this powerful cell platform can accelerate$nthe development, validation and improvement of DMD genetic therapies.