CNBP and myotonic dystrophy type 2: In the human genome, expansions of CCTG repeats found in intron 1 of the cellular nucleic acid-binding protein (CNBP) gene on chromosome 3q21 are associated with a complex multisystem disorder called myotonic dystrophy type 2 (DM2).1 These repeats are located in a part of the complex motif (TG)14–25(TCTG)4–10(CCTG)n (where n is the repeat length).1–3 In normal individuals, n is usually below 30 and the CCTG repeat tract is interrupted by one or more A/G/TCTG motif(s).