The 5′ Region of Intron 11 of the Dystrophin Gene Contains Target Sequences for Mobile Elements and Three Overlapping ORFs

We have characterised the 2371 bp 5′ end of intron 11 of the dystrophin gene. Comparative analysis of this intronic region revealed homologies with the following sequences: regions containing mobile elements; target sites for numerous transcription factors, two resolvases, and a histone-like DNA binding protein; three eukaryotic promoters. In addition, we identified three partially overlapping ORFs, and transcription analysis confirmed that one of these is expressed, representing the first gene reported to overlap the human dystrophin gene. We have also characterised a 136 bp sequence rearranged in intron 11 in a patient affected by X-linked dilated cardiomyopathy due to a dystrophinopathy. This is a multiple copy sequence with features of a repetitive element. Its comparative analysis showed a very high homology with human genomic and EST regions, adjacent and clustered withAlu, LINE1,andTHEelements. The pattern of homology suggests that it may represent a novelAlu-like, transcriptionally active sequence with a possible retrotransposable capacity. We hypothesise that the 5′ region of the dystrophin intron 11, containing common target areas for the insertion of mobile elements, may have a role in the rearrangement of this novelAlu-likesequence.