One of these disorders, myotonic dystrophy type 2 (DM2; OMIM_#602668), is connected to expansion of a (CCTG)n repeat tract located in the first intron of the cellular retroviral nucleic acid-binding protein (CNBP; also called zinc finger protein 9, ZNF9) gene. This evidence concerns the gene CNBP and Proximal myotonic myopathy.