Familial dilated cardiomyopathy. Clinical and genetic characteristics

Gender-related differences in heart failure: beyond the "one-size-fits-all" paradigm

Cardiovascular diseases show many sex-related differences in prevalence, etiology, phenotype expression, and outcomes. Complex molecular mechanisms underlie this diverse pathological manifestation, from sex-determined differential gene expression to sex hormones interaction with their specific receptors in different tissues. More recently, differential non-coding RNAs regulation also turned out to be an involved mechanism. This review focuses on sex impact on the various heart failure syndromes, including coronary artery disease, heart failure with preserved ejection fraction and with reduced ejection fraction, with particular attention to dilated cardiomyopathy. Despite similar genetic predisposition in terms of identified causative mutations, other causes, such as cardiotoxic drugs exposure or stress-induced cardiomyopathy, are more prevalent in women. Beyond this, differences in disease presentation and natural history reveal a more severe clinical onset with otherwise better long-term outcomes in women compared to men. Understanding the varying characteristics of disease manifestation and outcomes is warranted for a prompt and tailored treatment for both men and women. This is a mandatory step in the road to the personalized medicine. Moreover, despite a higher enrollment in the last years, the under-representation of females in clinical trials is the first obstacle to overcome in the long way to develop appropriate sex-based therapy approach.

Integrin-linked kinase mediates force transduction in cardiomyocytes by modulating SERCA2a/PLN function

Human dilated cardiomyopathy (DCM) manifests as a profound reduction in biventricular cardiac function that typically progresses to death or cardiac transplantation. There is no effective mechanism-based therapy currently available for DCM, in part because the transduction of mechanical load into dynamic changes in cardiac contractility (termed mechanotransduction) remains an incompletely understood process during both normal cardiac function and in disease states. Here we show that the mechanoreceptor protein integrin-linked kinase (ILK) mediates cardiomyocyte force transduction through regulation of the key calcium regulatory protein sarcoplasmic/endoplasmic reticulum Ca(2+)ATPase isoform 2a (SERCA-2a) and phosphorylation of phospholamban (PLN) in the human heart. A non-oncogenic ILK mutation with a synthetic point mutation in the pleckstrin homology-like domain (ILK(R211A)) is shown to enhance global cardiac function through SERCA-2a/PLN. Thus, ILK serves to link mechanoreception to the dynamic modulation of cardiac contractility through a previously undiscovered interaction with the functional SERCA-2a/PLN module that can be exploited to rescue impaired mechanotransduction in DCM.

A novel arginine to tryptophan (R144W) mutation in troponin T (cTnT) gene in an indian multigenerational family with dilated cardiomyopathy (FDCM)

Cardiomyopathy is a major cause of heart failure and sudden cardiac death; several mutations in sarcomeric protein genes have been associated with this disease. Our aim in the present study is to investigate the genetic variations in Troponin T (cTnT) gene and its association with dilated cardiomyopathy (DCM) in south-Indian patients. Analyses of all the exons and exon-intron boundaries of cTnT in 147 DCM and in 207 healthy controls had revealed a total of 15 SNPs and a 5 bp INDEL; of which, polymorphic SNPs were compared with the HapMap population data. Interestingly, a novel R144W mutation, that substitutes polar-neutral tryptophan for a highly conserved basic arginine in cTnT, altering the charge drastically, was identified in a DCM, with a family history of sudden-cardiac death (SCD). This mutation was found within the tropomyosin (TPM1) binding domain, and was evolutionarily conserved across species, therefore it is expected to have a significant impact on the structure and function of the protein. Family studies had revealed that the R144W is co-segregating with disease in the family as an autosomal dominant trait, but it was completely absent in 207 healthy controls and in 162 previously studied HCM patients. Further screening of the proband and three of his family members (positive for R144W mutant) with eight other genes β-MYH7, MYBPC3, TPM1, TNNI3, TTN, ACTC, MYL2 and MYL3, did not reveal any disease causing mutation, proposing the absence of compound heterozygosity. Therefore, we strongly suggest that the novel R144W unique/private mutant identified in this study is associated with FDCM. This is furthermore signifying the unique genetic architecture of Indian population.