Splicing assays using differentiated primary myoblasts confirmed that elevated HNRNPA1 protein levels reproduced DM1 splicing patterns, while HITS-CLIP of HSALR muscle overexpressing HNRNPA1 revealed that >30% of HNRNPA1 targets overlapped with MBNL1 target RNAs. Here, HNRNPA1 is linked to myotonic dystrophy type 1.