In order to examine the changes in gene expression between normal and myotonic dystrophic animals, gene expression array studies were done with extensor digitorum longus (EDL) of transgenic HSALR line 20b mice using Affymetrix MOE430 2.0 microarrays. We used EDL muscle from transgenic HSALR line 20b mice, maintained as homozygotes in an FVB inbred background and wild-type FVB mice purchased from Taconic. Overall design: Affymetrix gene expression arrays were performed on HSALR and wild type EDL muscle