This transgene consists of a 654-bp fragment of rat alpha-myosin heavy chain promoter inserted upstream of a chimeric Ngfb mini-gene containing noncoding exon 1 and a portion of intron 1 of the mouse Ngfb gene fused to sequences from intron 3 through exon 4 of the rat Ngfb gene. Northern blots analysis shows cardiac specific expression of Ngfb. Three lines were established (2-4), with line 4 containing 8-10 copies of the transgene and lines 2 and 3 containing between 15 and 20 copies. Line 4 is chosen as a representative line as it continues to exhibit the cardiac pathology due to hypomethylation while lines 2 and 3 are hypermethylated and show loss of the phenotype after propagation for about 10 generations.