In contrast, (CTG)n•(CAG)n expansion at the DMPK 3' UTR alters the chromatin structure of the region, downregulates transcription of the locus and, as at the JPH3 gene produce poly-(CUG) pre-mRNAs respectively in DM1 and HDL2 patients that sequester the MBNL (CUG) binding proteins, leading to trans-dominant interference with the normal splicing of multiple RNAs. This evidence concerns the gene DMPK and myotonic dystrophy type 1.