Editing Repeated sequence (DNA) (section)

=== Myotonic dystrophy ===
[[Myotonic dystrophy]] is a disorder that presents as muscle weakness and consists of two main types: DM1 and DM2.<ref>{{cite journal | vauthors = Hahn C, Salajegheh MK | title = Myotonic disorders: A review article | journal = Iranian Journal of Neurology | volume = 15 | issue = 1 | pages = 46–53 | date = January 2016 | pmid = 27141276 | pmc = 4852070 }}</ref> Both types of myotonic dystrophy are due to expanded DNA sequences. In DM1 the DNA sequence that is expanded is CTG while in DM2 it is CCTG. These two sequences are found on different genes with the expanded sequence in DM2 being found on the ''ZNF9'' gene and the expanded sequence in DM1 found on the ''DMPK'' gene. The two genes don't encode for proteins unlike other disorders like Huntington's disease or Fragile X syndrome. It has been shown, however, that there is a link between RNA toxicity and the repeat sequences in DM1 and DM2.