H19 and cardiomyopathy: That is, hearts from 6 month LOI mice carrying the H19 transgene are not enlarged as determined by heart weight/tibia length ratios (LOI = 12.9 ± 0.6 mg/mm, N = 3; LOI+ H19 BAC transgene = 11.5 ± 0.7, N = 3; p<0.05), are not fibrotic (Figure 4A,B), and do not express cardiomyopathy markers (Figure 4C; Figure 4—figure supplement 1A).