MBNL1 and myotonic dystrophy: The formation of RNA ‘foci’ is widely regarded as being an RNA toxicity-related phenomenon, and in the case of myotonic dystrophy, MBNL1 depletion, through sequestration into RNA foci, causes the aberrant splicing of genes linked to a wide range of clinical symptoms.44 However, in the case of Huntington’s disease, these nuclear clusters might exert a protective effect, by retaining HTT1a in the nucleus and preventing it from being translated to generate the highly aggregation-prone and pathogenic exon 1 HTT protein.