ABSTRACT
<p><b>OBJECTIVE</b>To finish the work of sequencing the full sequence of intron 51 of dystrophin gene and understand its characteristic of sequence.</p><p><b>METHODS</b>The whole intron 51 was sequenced by primer walking. The sequencing results were analyzed by repeat sequences, matrix attachment region (MAR) and topoisomerase II cleavage sites. The residue sequences, after removal of the repetitive sequences, were subjected to the analysis of CpG islands, promoter, open reading frame (ORF) and unidentified low copy repeat sequence.</p><p><b>RESULTS</b>The acquired intron 51 sequence was composed of 38725 bp. Repetitive sequences constituted 37.53% of total intron sequence. The overall G+C content of intron 51 was 36.34%. There are four potential MARs in intron 51. Three of them are clustered in the 12 kb region near exon 51. Numerous ORFs were found on both strands, but no homologues proteins were found in Genbank CDS transcriptional peptide, PDB, SwissProt, PIR and PRF databases.</p><p><b>CONCLUSION</b>The expansion of intron 7 over the last 120 million years was mainly the result of L1 insertion into intron 7, and not all of repetitive sequences are associated with chromosomal rearrangement. No sequence of functional significance was found in intron 51. The results suggest that the cluster of MARs may be associated with the instability of intron 51.</p>