The condition is caused by unstable, simple nucleotide tandem repeats in thedystrophia myotonica protein kinase (DMPK) gene for myotonic dystrophy type 1(DM1) and in the cellular nucleic acid binding protein gene (CNBP) for myotonicdystrophy type 2 (DM2) [1, 2]. The gene discussed is CNBP; the disease is myotonic dystrophy type 1.