HLA-C and myotonic dystrophy type 1: To test the effect of specific silencing of the miRNA repressors of muscleblind in a Drosophila DM1 model, we studied Muscleblind expression in flies expressing 480 interrupted CTG repeats under the control of the muscle-specific driver Myosin heavy chain with simultaneous expression of sponge constructs (Mhc-Gal4 UAS-i(CTG)480 UAS-miR-XSP).