title: The evolution of an intron: analysis of a long, deletion-prone intron in the human dystrophin gene.
abstract: The sequence of a 112-kb region of the human dystrophin (DMD/BMD) gene encompassing the deletion prone intron 7 (110 kb) and the much shorter intron 8 (1.1 kb) has been determined. Recognizable insertion sequences account for approximately 40% of intron 7. LINE-1 and THE-1/LTR sequences occur in intron 7 with significantly higher frequency than would be expected statistically while Alu sequences are underrepresented. Intron 7 also contains numerous mammalian-wide interspersed repeats, a diverse range of medium reiteration repeats of unknown origin, and a sequence derived from a mariner transposon. By contrast, the shorter intron 8 contains no detectable insertion sequences. Dating of the LI and Alu sequences suggests that intron 7 has approximately doubled in size within the past 130 million years, and comparison with the corresponding intron from the pufferfish (Fugu rubripes) suggests that the intron has expanded some 44-fold over a period of 400 million years. The possible contribution of the insertion elements to the instability of intron 7 is discussed.
authors.affiliation: Department of Biochemistry, University of Otago, Dunedin, New Zealand.
authors.forename: J C
authors.initials: JC
authors.lastname: McNaughton
authors.forename: G
authors.initials: G
authors.lastname: Hughes
authors.forename: W A
authors.initials: WA
authors.lastname: Jones
authors.forename: P A
authors.initials: PA
authors.lastname: Stockwell
authors.forename: H J
authors.initials: HJ
authors.lastname: Klamut
authors.forename: G B
authors.initials: GB
authors.lastname: Petersen
mesh_terms: D001482:Base Composition; D016189:Dystrophin / Q000235:genetics*; D019143:Evolution, Molecular; D005796:Genes / Q000235:genetics; D006801:Humans; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion / Q000235:genetics
chemical_list: D016189:Dystrophin