Alternative splicing plays a major role in the adaptation of cardiac function exemplified by the isoform switch of titin, which adjusts ventricular filling. We previously identified a rat strain deficient in titin splicing. Using genetic mapping, we found a loss-of-function mutation in RBM20 as the underlying cause for the pathological titin isoform expression. Mutations in human RBM20 have previously been shown to cause dilated cardiomyopathy. We showed that the phenotype of Rbm20 deficient rats resembles the human pathology. Deep sequencing of the human and rat cardiac transcriptome revealed an RBM20 dependent regulation of alternative splicing. Additionally to titin we identified a set of 30 genes with conserved regulation between human and rat. This network is enriched for genes previously linked to cardiomyopathy, ion-homeostasis, and sarcomere biology. Our studies emphasize the importance of posttranscriptional regulation in cardiac function and provide mechanistic insights into the pathogenesis of human heart failure.

Carriers of LMNA mutations with a high risk of MVA can be identified using these risk factors. This facilitates selection of LMNA mutation carriers who are most likely to benefit from an ICD.

Advances in molecular genetics present new opportunities and challenges for cardiologists who manage patients and families with cardiomyopathies. The aims of this position statement of the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases are to review the general issues related to genetic counselling, family screening and genetic testing in families with a cardiomyopathy, and to provide key messages and suggestions for clinicians involved in their management.

Background-Muscle LIM protein (MLP) is an essential nuclear regulator of myogenic differentiation. Additionally, it may act as an integrator of protein assembly of the actin-based cytoskeleton. MLP-knockout mice develop a marked cardiac hypertrophy reaction and dilated cardiomyopathy (DCM). MLP is therefore a candidate gene for heritable forms of hypertrophic cardiomyopathy (HCM) and DCM in humans. Methods and Results-We analyzed 1100 unrelated individuals (400 patients with DCM, 200 patients with HCM, and 500 controls) for mutations in the human CRP3 gene that encodes MLP. We found 3 different missense mutations in 3 unrelated patients with familial HCM but detected no mutation in the DCM group or the controls. All mutations predicted an amino acid exchange at highly conserved residues in the functionally important LIM1 domain, which is responsible for interaction with ␣-actinin and with certain muscle-specific transcription factors. Protein-binding studies indicate that mutations in the CRP3 gene lead to a decreased binding activity of MLP to ␣-actinin.