Potassium channels are important regulators of proliferation in many cell types.13, 14, 15 To understand the molecular events that lead to delayed myotube fusion, we assessed the role of potassium channels in regulating proliferation, matrix metalloproteinase (MMP) levels, migration, and fusion of skeletal myoblasts from patients with DM1 and from healthy volunteers. Here, KCNA3 is linked to myotonic dystrophy type 1.