Exon 13 was replaced with a floxed neo cassette and an exon 13 containing a deletion of three base pairs that results in the deletion of lysine at position 210 (K210). The neo cassette was removed by germ line, cre-mediated recombination. This mutation mimicks one identified in human patients with dilated cardiomyopathy. Similar levels of troponin T protein are detected in cardiac myofibrils isolated from the hearts of mice homozygous for this mutation and of wild-type mice by sodium dodecyl sulftate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis for total protein. (J:137784, J:173751)