Phenotypic Spectrum of Mutations in Cardiolaminopathies

Phenotypic plasticity of mutations in LMNA, which encodes Lamin A/C, is unsurpassed by any other gene. Mutations in LMNA are responsible for least a dozen distinct phenotype sthat affect various mesenchymal organs and are collectively referred to as lamino - pathies or less frequently envelopathies. Cardiolaminopathies are a subset of lamino - pathies wherein involvement of the heart is the most prominent feature. The typical phenotype of cardiolaminopathies encompasses dilated cardiomyopathy (DCM) and conduction defects. LMNA is probably the most common causal gene for human DCM, being responsible up to 8% of all familial DCM. Several hundred mutations in the LMNA gene have already been described. The p.R644C mutation is the most commonly reported mutation in cardiolaminopathies. The phenotype in cardiolaminopathies is notable for a rapid progression of cardiac failure, conduction defects and arrhythmias, often necessitating implantation of a pacemaker and/or a defibrillator. The molecular pathogenesis of cardiolamino - pathies is poorly understood. Studies in animal models and cultured cells suggest involvement of the Mitogen-Activated Protein Kinase (MAPK) and transforming growth factor –β1 pathways. Comprehensive molecular genetics studies complemented with mechanistic studies are needed to delineate the mechanistic underpinnings of cardiolaminopathies, prerequisite for the ultimate cure of these potentially deadly disorders.