title: A novel cryptic exon in intron 3 of the dystrophin gene was incorporated into dystrophin mRNA with a single nucleotide deletion in exon 5.
abstract: The dystrophin gene, which is mutated in Duchenne muscular dystrophy, is the largest human gene. A full spectrum of the gene transcripts has not been fully elucidated yet, although two cryptic exons have so far been identified in the 5' region of the dystrophin gene. Here, a novel dystrophin mRNA containing a 62-nucleotide insertion between exons 3 and 4 was identified in lymphocytes from a Japanese Duchenne muscular dystrophy patient with a single nucleotide deletion in exon 5. The inserted 62-nucleotide sequence was found to be homologous to part of intron 3 and it was revealed that the insertion possessed branch point and both acceptor and donor splice site consensus sequences perfectly. Therefore, the 62-bp insertion sequence was considered to be a novel exon and was designated as exon 3a. However, this insertion was not present in the patient's muscle and 12 different normal tissues that were screened. The physiological role of the novel cryptic exon remains to be clarified.
authors.affiliation: Division of Molecular Medicine, Kobe University Graduate School of Medicine, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Suminaga
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takeshima
authors.forename: Kayo
authors.initials: K
authors.lastname: Adachi
authors.forename: Mariko
authors.initials: M
authors.lastname: Yagi
authors.forename: Hajime
authors.initials: H
authors.lastname: Nakamura
authors.forename: Masafumi
authors.initials: M
authors.lastname: Matsuo
mesh_terms: D017398:Alternative Splicing; D016189:Dystrophin / Q000235:genetics*; D005091:Exons / Q000235:genetics; D006801:Humans; D007438:Introns / Q000235:genetics; D020388:Muscular Dystrophy, Duchenne / Q000235:genetics; D020641:Polymorphism, Single Nucleotide
chemical_list: D016189:Dystrophin