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Contains fulltext : 284808.pdf (Publisher’s version ) (Open Access), BACKGROUND: Although genotyping allows family screening and influences risk-stratification in patients with nonischemic dilated cardiomyopathy (DCM) or isolated left ventricular systolic dysfunction (LVSD), its result is negative in a significant number of patients, limiting its widespread adoption. OBJECTIVES: This study sought to develop and externally validate a score that predicts the probability for a positive genetic test result (G+) in DCM/LVSD. METHODS: Clinical, electrocardiogram, and echocardiographic variables were collected in 1,015 genotyped patients from Spain with DCM/LVSD. Multivariable logistic regression analysis was used to identify variables independently predicting G+, which were summed to create the Madrid Genotype Score. The external validation sample comprised 1,097 genotyped patients from the Maastricht and Trieste registries. RESULTS: A G+ result was found in 377 (37%) and 289 (26%) patients from the derivation and validation cohorts, respectively. Independent predictors of a G+ result in the derivation cohort were: family history of DCM (OR: 2.29; 95% CI: 1.73-3.04; P < 0.001), low electrocardiogram voltage in peripheral leads (OR: 3.61; 95% CI: 2.38-5.49; P < 0.001), skeletal myopathy (OR: 3.42; 95% CI: 1.60-7.31; P = 0.001), absence of hypertension (OR: 2.28; 95% CI: 1.67-3.13; P < 0.001), and absence of left bundle branch block (OR: 3.58; 95% CI: 2.57-5.01; P < 0.001). A score containing these factors predicted a G+ result, ranging from 3% when all predictors were absent to 79% when ≥4 predictors were present. Internal validation provided a C-statistic of 0.74 (95% CI: 0.71-0.77) and a calibration slope of 0.94 (95% CI: 0.80-1.10). The C-statistic in the external validation cohort was 0.74 (95% CI: 0.71-0.78). CONCLUSIONS: The Madrid Genotype Score is an accurate tool to predict a G+ result in DCM/LVSD.

Contains fulltext : 284808.pdf (Publisher’s version ) (Open Access), BACKGROUND: Although genotyping allows family screening and influences risk-stratification in patients with nonischemic dilated cardiomyopathy (DCM) or isolated left ventricular systolic dysfunction (LVSD), its result is negative in a significant number of patients, limiting its widespread adoption. OBJECTIVES: This study sought to develop and externally validate a score that predicts the probability for a positive genetic test result (G+) in DCM/LVSD. METHODS: Clinical, electrocardiogram, and echocardiographic variables were collected in 1,015 genotyped patients from Spain with DCM/LVSD. Multivariable logistic regression analysis was used to identify variables independently predicting G+, which were summed to create the Madrid Genotype Score. The external validation sample comprised 1,097 genotyped patients from the Maastricht and Trieste registries. RESULTS: A G+ result was found in 377 (37%) and 289 (26%) patients from the derivation and validation cohorts, respectively. Independent predictors of a G+ result in the derivation cohort were: family history of DCM (OR: 2.29; 95% CI: 1.73-3.04; P < 0.001), low electrocardiogram voltage in peripheral leads (OR: 3.61; 95% CI: 2.38-5.49; P < 0.001), skeletal myopathy (OR: 3.42; 95% CI: 1.60-7.31; P = 0.001), absence of hypertension (OR: 2.28; 95% CI: 1.67-3.13; P < 0.001), and absence of left bundle branch block (OR: 3.58; 95% CI: 2.57-5.01; P < 0.001). A score containing these factors predicted a G+ result, ranging from 3% when all predictors were absent to 79% when ≥4 predictors were present. Internal validation provided a C-statistic of 0.74 (95% CI: 0.71-0.77) and a calibration slope of 0.94 (95% CI: 0.80-1.10). The C-statistic in the external validation cohort was 0.74 (95% CI: 0.71-0.78). CONCLUSIONS: The Madrid Genotype Score is an accurate tool to predict a G+ result in DCM/LVSD.

Recent studies have demonstrated that genetic factors are likely to play a major role in the pathogenesis of idiopathic dilated cardiomyopathy (IDC), In clinical surveys, a familial trait has been demonstrated in 20 to 30% of idiopathic dilated cardiomyopathy patients (familial dilated cardiomyopathy), Molecular genetic studies have confirmed the clinical hypothesis of genetic heterogeneity in familial dilated cardiomyopathy, and are currently producing relevant advances in the understanding of this disease, The autosomal dominant form is considered to be the most frequent form of inherited idiopathic dilated cardiomyopathy. After the exclusion of a large series of candidate genes, the first familial dilated cardiomyopathy gene has been mapped to the long arm of chromosome 9, A second locus has been found on chromosome 1, Moreover, in two large families, characterized by a peculiar form of conduction delays and later development of myocardial dysfunction, the disease loci have been mapped to chromosome 1 and 3, respectively, The identification of the disease genes is in progress, In families with X-linked dilated cardiomyopathy, the disease gene has been identified as the dystrophin gene, The 5' end of the gene appears to be the critical region for the development of dilated cardiomyopathy without clinical evidence of muscle dystrophy. Furthermore, other cytoskeletal proteins, such as adhalin, could be involved in the pathogenesis of familial dilated cardiomyopathy, In familial right ventricular cardiomyopathy (or arrhythmogenic right ventricular dysplasia) characterized by isolated or prevalent right ventricular involvement, three different disease loci have been identified so far : two localized on the long arm of chromosome 14 and one on chromosome 1. The disease genes are still unknown and are currently under investigation, The study of the genetic factors at the molecular level is starting to elucidate the pathogenetic mechanisms of idiopathic dilated cardiomyo

Recent studies have demonstrated that genetic factors are likely to play a major role in the pathogenesis of idiopathic dilated cardiomyopathy (IDC), In clinical surveys, a familial trait has been demonstrated in 20 to 30% of idiopathic dilated cardiomyopathy patients (familial dilated cardiomyopathy), Molecular genetic studies have confirmed the clinical hypothesis of genetic heterogeneity in familial dilated cardiomyopathy, and are currently producing relevant advances in the understanding of this disease, The autosomal dominant form is considered to be the most frequent form of inherited idiopathic dilated cardiomyopathy. After the exclusion of a large series of candidate genes, the first familial dilated cardiomyopathy gene has been mapped to the long arm of chromosome 9, A second locus has been found on chromosome 1, Moreover, in two large families, characterized by a peculiar form of conduction delays and later development of myocardial dysfunction, the disease loci have been mapped to chromosome 1 and 3, respectively, The identification of the disease genes is in progress, In families with X-linked dilated cardiomyopathy, the disease gene has been identified as the dystrophin gene, The 5' end of the gene appears to be the critical region for the development of dilated cardiomyopathy without clinical evidence of muscle dystrophy. Furthermore, other cytoskeletal proteins, such as adhalin, could be involved in the pathogenesis of familial dilated cardiomyopathy, In familial right ventricular cardiomyopathy (or arrhythmogenic right ventricular dysplasia) characterized by isolated or prevalent right ventricular involvement, three different disease loci have been identified so far : two localized on the long arm of chromosome 14 and one on chromosome 1. The disease genes are still unknown and are currently under investigation, The study of the genetic factors at the molecular level is starting to elucidate the pathogenetic mechanisms of idiopathic dilated cardiomyo

Two new cases of dilated cardiomyopathy (DC) caused by dystrophinopathy are reported. One patient, a 21 year old man, had a family history of X linked DC, while the other, a 52 year old man, had sporadic disease. Each had abnormal dystrophin immunostaining in muscle or cardiac biopsy specimens, but neither had muscle weakness. Serum creatine kinase activity was raised only in the patient with familial disease. Analysis of dystrophin gene mutations showed a deletion of exons 48-49 in the patient with familial DC and of exons 49-51 in the other. Dystrophin transcription in cardiac tissue from the patient with sporadic disease showed abundant expression, predominantly of the muscle isoform. This study, together with previous reports, suggests that some patients with DC have a dystrophinopathy that can be diagnosed using a combination of biochemical and genetic analyses.

Two new cases of dilated cardiomyopathy (DC) caused by dystrophinopathy are reported. One patient, a 21 year old man, had a family history of X linked DC, while the other, a 52 year old man, had sporadic disease. Each had abnormal dystrophin immunostaining in muscle or cardiac biopsy specimens, but neither had muscle weakness. Serum creatine kinase activity was raised only in the patient with familial disease. Analysis of dystrophin gene mutations showed a deletion of exons 48-49 in the patient with familial DC and of exons 49-51 in the other. Dystrophin transcription in cardiac tissue from the patient with sporadic disease showed abundant expression, predominantly of the muscle isoform. This study, together with previous reports, suggests that some patients with DC have a dystrophinopathy that can be diagnosed using a combination of biochemical and genetic analyses.

X-linked dilated cardiomyopathy (XLDC) is a familial heart disease presenting in young males as a rapidly progressive congestive heart failure, without clinical signs of skeletal myopathy. This condition has recently been linked to the dystrophin gene in some families and deletions encompassing the genomic region coding for the first muscle exon have been detected. In order to identify the defect responsible for this disease at the molecular level and to understand the reasons for the selective heart involvement, a family with a severe form of XLDC was studied. In the affected members, no deletions of the dystrophin gene were observed. Analysis of the muscle promoter, first exon and intron regions revealed the presence of a single point mutation at the first exon-intron boundary, inactivating the universally conserved 5' splice site consensus sequence of the first intron. This mutation introduced a new restriction site for Msel, which cosegregates with the disease in the analyzed family. Expression of the major dystrophin mRNA isoforms (from the muscle-, brain- and Purkinje cell-promoters) was completely abolished in the myocardium, while the brain- and Purkinje cell- (but not the muscle-) isoforms were detectable in the skeletal muscle. Immunocytochemical studies with anti-dystrophin antibodies showed that the protein was reduced in quantity but normally distributed in the skeletal muscle, while it was undetectable in the cardiac muscle. These findings indicate that expression of the muscle dystrophin isoform is critical for myocardial function and suggest that selective heart involvement in dystrophin-linked dilated cardiomyopathy is related to the absence, in the heart, of a compensatory expression of dystrophin from alternative promoters.

X-linked dilated cardiomyopathy (XLDC) is a familial heart disease presenting in young males as a rapidly progressive congestive heart failure, without clinical signs of skeletal myopathy. This condition has recently been linked to the dystrophin gene in some families and deletions encompassing the genomic region coding for the first muscle exon have been detected. In order to identify the defect responsible for this disease at the molecular level and to understand the reasons for the selective heart involvement, a family with a severe form of XLDC was studied. In the affected members, no deletions of the dystrophin gene were observed. Analysis of the muscle promoter, first exon and intron regions revealed the presence of a single point mutation at the first exon-intron boundary, inactivating the universally conserved 5' splice site consensus sequence of the first intron. This mutation introduced a new restriction site for Msel, which cosegregates with the disease in the analyzed family. Expression of the major dystrophin mRNA isoforms (from the muscle-, brain- and Purkinje cell-promoters) was completely abolished in the myocardium, while the brain- and Purkinje cell- (but not the muscle-) isoforms were detectable in the skeletal muscle. Immunocytochemical studies with anti-dystrophin antibodies showed that the protein was reduced in quantity but normally distributed in the skeletal muscle, while it was undetectable in the cardiac muscle. These findings indicate that expression of the muscle dystrophin isoform is critical for myocardial function and suggest that selective heart involvement in dystrophin-linked dilated cardiomyopathy is related to the absence, in the heart, of a compensatory expression of dystrophin from alternative promoters.