Clinical and Functional Characterization of a Novel Mutation in Lamin A/C Gene in a Multigenerational Family with Arrhythmogenic Cardiac Laminopathy

• DOI: 10.1371/journal.pone.0121723
• Publication Date: 2015-04-03T15:51:47Z
• Authors: Cinzia Forleo; Monica Carmosino; Nicoletta Resta; Alessandra Rampazzo; Rosanna Valecce; Sandro Sorrentino; Massimo Iacoviello; Francesco Pisani; Giuseppe Procino; Andrea Gerbino; Arnaldo Scardapane; Cristiano Simone; Martina Calore; Silvia Torretta; Maria Svelto; Stefano Favale
• Keywords: Male; Penetrance; Apoptosis; Arrhythmias; 0302 clinical medicine; Cardiac Conduction System Disease; Dilated; Age Factor; Arrhythmogenic Right Ventricular Dysplasia; Brugada Syndrome; Q; R; Age Factors; Exons; Middle Aged; Lamin Type A; Pedigree; 3. Good health; Death; Medicine; Female; Case-Control Studie; Cardiac; Human; Research Article; Adult; Cardiomyopathy, Dilated; Heterozygote; Adolescent; Cardiomyopathy; Science; Molecular Sequence Data; Primary Cell Culture; Exon; Genetic Association Studie; 03 medical and health sciences; Heart Conduction System; Humans; Genetic Predisposition to Disease; Amino Acid Sequence; Genetic Association Studies; Myocytes; Adolescent; Adult; Age Factors; Amino Acid Sequence; Apoptosis; Arrhythmias; Cardiac; Arrhythmogenic Right Ventricular Dysplasia; Brugada Syndrome; Cardiac Conduction System Disease; Cardiomyopathy; Dilated; Case-Control Studies; Death; Sudden; Cardiac; Exons; Female; Genetic Association Studies; Genetic Predisposition to Disease; Heart Conduction System; Heterozygote; Humans; Lamin Type A; Male; Middle Aged; Molecular Sequence Data; Myocytes; Cardiac; Pedigree; Penetrance; Primary Cell Culture; Sequence Alignment; Mutation; Apoptosi; Arrhythmias, Cardiac; Sudden; Death, Sudden, Cardiac; Case-Control Studies; Mutation; Sequence Alignment

Mutations in the lamin A/C gene (LMNA) were associated with dilated cardiomyopathy (DCM) and, recently, were related to severe forms of arrhythmogenic right ventricular cardiomyopathy (ARVC). Both genetic and phenotypic overlap between DCM and ARVC was observed; molecular pathomechanisms leading to the cardiac phenotypes caused by LMNA mutations are not yet fully elucidated. This study involved a large Italian family, spanning 4 generations, with arrhythmogenic cardiomyopathy of different phenotypes, including ARVC, DCM, system conduction defects, ventricular arrhythmias, and sudden cardiac death. Mutation screening of LMNA and ARVC-related genes PKP2, DSP, DSG2, DSC2, JUP, and CTNNA3 was performed. We identified a novel heterozygous mutation (c.418_438dup) in LMNA gene exon 2, occurring in a highly conserved protein domain across several species. This newly identified variant was not found in 250 ethnically-matched control subjects. Genotype-phenotype correlation studies suggested a co-segregation of the LMNA mutation with the disease phenotype and an incomplete and age-related penetrance. Based on clinical, pedigree, and molecular genetic data, this mutation was considered likely disease-causing. To clarify its potential pathophysiologic impact, functional characterization of this LMNA mutant was performed in cultured cardiomyocytes expressing EGFP-tagged wild-type and mutated LMNA constructs, and indicated an increased nuclear envelope fragility, leading to stress-induced apoptosis as the main pathogenetic mechanism. This study further expands the role of the LMNA gene in the pathogenesis of cardiac laminopathies, suggesting that LMNA should be included in mutation screening of patients with suspected arrhythmogenic cardiomyopathy, particularly when they have ECG evidence for conduction defects. The combination of clinical, genetic, and functional data contribute insights into the pathogenesis of this form of life-threatening arrhythmogenic cardiac laminopathy.