MBNL1 and myotonic dystrophy: Interestingly, MBNL1, a main contributor to myotonic dystrophy, shows the same double exon skipping event of exons 5 and 6 as in myotonic dystrophy type I. There are intron exclusion events in β-tubulin TUBB6 and FHL1, of which the latter is a component of the nuclear envelope and differentially expressed in FSHD, as described above.