Muscleblind-like proteins (Mbnl1 and Mbnl2) are sequestered in various tissues within the neuromuscular diseases of myotonic dystrophy types 1 (DM1) and 2 (DM2) in response to expansions of CUG repeats in the 3′UTR of the myotonic dystrophy protein kinase (DMPK) (Harley et al., 1992; Mahadevan et al., 1992), or CCUG repeats in the zinc finger protein 9 (ZNF9) (Ranum et al., 1998), respectively. The gene discussed is MBNL1; the disease is myotonic dystrophy type 1.