DMPK and myotonic dystrophy: Examples include DMPK (OMIM#605377) (CTG Expansion), within which a trinucleotide expansion of 50 repeat units (150 base pairs) can result in myotonic dystrophy (OMIM#160900), TCF4 (OMIM#602272) (CTG Expansion), a gene associated with Fuchs endothelial corneal dystrophy (OMIM#613267) which is caused by an STR expansion of more than 150 base pairs, and AR (OMIM#313700) (GCA Expansion), in which a 114-base pair expansion within the gene results in muscular atrophy of Kennedy (OMIM#313200).