The most prevalent form of adult-onset muscular dystrophy (Harper 2009), myotonic dystrophy type 1 (DM1), results from a CTG expansion in the 3′ UTR of the dystrophia myotonica-protein kinase gene (Brook et al. 1992; Mahadevan et al. 1992). The gene discussed is WEE1; the disease is myotonic dystrophy type 1.