MBNL1 and cardiac arrhythmia: Other messages bound by both factors whose expression responded to CELF1 induction and whose localization changed in response to Mbnl1 depletion (Results) included Kcnj2, a cardiac inward rectifier potassium channel whose mutation is associated with a syndrome that involves cardiac arrhythmia (Andelfinger et al. 2002), and the sine oculis binding protein homolog Sobp, mutations of which have been linked to intellectual disability (Birk et al. 2010).