We previously identified a dystrophin intron 11 rearrangement in one family with X-linked dilated cardiomyopathy, causing incorporation of an aberrant exon in a tissue-specific manner. In this study we analyzed the role of different intron 11 genomic regions in the regulation of splicing by using mini-genes based approach, in C2C 12 (skeletal muscle) myoblasts and myotubes, H9C2 cardiomyocytes, and HeLa cells. We show that inclusion of the aberrant exon is favored in H9C2 and differentiated C2C12 myotubes. These data suggest that the aberrant exon undergoes a differentiation-specific splicing. Unexpectedly, length of intron has a favorable effect in inclusion of the aberrant exon in the cardiac cells, suggesting that cardiac cells might be more prone to steric hindrance of trans-acting factors, involved in the inclusion of the aberrant exon. Furthermore, the cultured cell system used can serve as a suitable model to study human alternative splicing. (C) 2004 Elsevier Inc. All rights reserved.