DIS3 and Miyoshi myopathy: Interestingly, as reported by Tomecki et al., Northern blot analyses in HEK293 cells expressing MM-associated DIS3 mutations (such as R780K) revealed the accumulation of the majority of analyzed exosome substrates, including 5.8S processing intermediates, tRNAs, RNA polymerase III transcripts and PROMPTs (i.e. PROMoter uPstream Transcripts), these latters generated 0.5 to 2.5 kb upstream of active transcription start sites and rapidly turned over by the RNA exosome [10].