MBNL1 and myotonic dystrophy type 1: MBNL sequestration by CUG expansion RNAs in DM1 results in enhanced APP exon 7 skipping (2), while HNRNPA1 knockdown leads to expression of full-length APP (+exon 7), which has been suggested to lead to increases in Aβ peptide secretion and amyloid plaques.