Mutations in TRIM63 cause an autosomal-recessive form of hypertrophic cardiomyopathy

Objective: Up to 50% of patients with hypertrophic cardiomyopathy (HCM) show no disease-causing variants in genetic studies. TRIM63 has been suggested as a candidate gene for the development of cardiomyopathies, although evidence for a causative role in HCM is limited. We sought to investigate the relationship between rare variants in TRIM63 and the development of HCM. Methods: TRIM63 was sequenced by next generation sequencing in 4867 index cases with a clinical diagnosis of HCM and in 3628 probands with other cardiomyopathies. Additionally, 3136 index cases with familial cardiovascular diseases other than cardiomyopathy (mainly channelopathies and aortic diseases) were used as controls. Results: Sixteen index cases with rare homozygous or compound heterozygous variants in TRIM63 (15 HCM and one restrictive cardiomyopathy) were included. No homozygous or compound heterozygous were identified in the control population. Familial evaluation showed that only homozygous and compound heterozygous had signs of disease, whereas all heterozygous family members were healthy. The mean age at diagnosis was 35 years (range 15-69). Fifty per cent of patients had concentric left ventricular hypertrophy (LVH) and 45% were asymptomatic at the moment of the first examination. Significant degrees of late gadolinium enhancement were detected in 80% of affected individuals, and 20% of patients had left ventricular (LV) systolic dysfunction. Fifty per cent had non-sustained ventricular tachycardia. Twenty per cent of patients suffered an adverse cerebrovascular event (20%). Conclusion: TRIM63 appears to be an uncommon cause of HCM inherited in an autosomal-recessive manner and associated with concentric LVH and a high rate of LV dysfunction

The interpretation of genetic tests in inherited cardiovascular diseases

The inherited cardiovascular diseases, including cardiomyopathies, channelopaties and inherited diseases of the aorta are heterogeneous conditions with highly variable morphologic and functional features, clinical presentation, evolution and prognosis. Hundreds of mutations in different genes have been associated with each one of these entities and it is likely that this genetic heterogeneity is one of the main reasons for the variability in their clinical expression. Information from the genetic studies may help the clinicians to diagnose the diseases in early stages, to identify relatives at risk and those who do not require periodic follow up, and may also provide prognostic information. An appropriate and accurate interpretation of the genetic tests is required to get all the potential advantages of these studies. This interpretation is not simple and requires information, specialized knowledge and dedication to the task. The first step is to decide which the appropriate genetic test is. Negative results do not exclude the disease and in that situation we need to decide whether to continue the screening or not. When the genetic study identifies one or multiple genetic variants we will have to evaluate their frequency in the general population (polymorphisms vs. mutations) and their pathogenicity. To establish whether a given variant is associated with the disease we have to integrate both basic and clinical information. When a variant is considered potentially pathogenic we still have to evaluate whether this variant explains the phenotype of the patient and of his/her family (more than one mutation may be present). Finally, we have to analyse all the available information about the consequences of the identified mutations and to integrate this information with all the available clinical data of the patient and family. With this approach, genetic test becomes a very useful tool in the management of all the inherited cardiovascular diseases

The interpretation of genetic tests in inherited cardiovascular diseases

The inherited cardiovascular diseases, including cardiomyopathies, channelopaties and inherited diseases of the aorta are heterogeneous conditions with highly variable morphologic and functional features, clinical presentation, evolution and prognosis. Hundreds of mutations in different genes have been associated with each one of these entities and it is likely that this genetic heterogeneity is one of the main reasons for the variability in their clinical expression. Information from the genetic studies may help the clinicians to diagnose the diseases in early stages, to identify relatives at risk and those who do not require periodic follow up, and may also provide prognostic information. An appropriate and accurate interpretation of the genetic tests is required to get all the potential advantages of these studies. This interpretation is not simple and requires information, specialized knowledge and dedication to the task. The first step is to decide which the appropriate genetic test is. Negative results do not exclude the disease and in that situation we need to decide whether to continue the screening or not. When the genetic study identifies one or multiple genetic variants we will have to evaluate their frequency in the general population (polymorphisms vs. mutations) and their pathogenicity. To establish whether a given variant is associated with the disease we have to integrate both basic and clinical information. When a variant is considered potentially pathogenic we still have to evaluate whether this variant explains the phenotype of the patient and of his/her family (more than one mutation may be present). Finally, we have to analyse all the available information about the consequences of the identified mutations and to integrate this information with all the available clinical data of the patient and family. With this approach, genetic test becomes a very useful tool in the management of all the inherited cardiovascular diseases

European Heart Journal Advance

Aim Numerous genes are known to cause dilated cardiomyopathy (DCM). However, until now technological limitations have hindered elucidation of the contribution of all clinically relevant disease genes to DCM phenotypes in larger cohorts. We now utilized next-generation sequencing to overcome these limitations and screened all DCM disease genes in a large cohort. Methods and results In this multi-centre, multi-national study, we have enrolled 639 patients with sporadic or familial DCM. To all samples, we applied a standardized protocol for ultra-high coverage next-generation sequencing of 84 genes, leading to 99.1% coverage of the target region with at least 50-fold and a mean read depth of 2415. In this well characterized cohort, we find the highest number of known cardiomyopathy mutations in plakophilin-2, myosin-binding protein C-3, and desmoplakin. When we include yet unknown but predicted disease variants, we find titin, plakophilin-2, myosin-binding protein-C 3, desmoplakin, ryanodine receptor 2, desmocollin-2, desmoglein-2, and SCN5A variants among the most commonly mutated genes. The overlap between DCM, hypertrophic cardiomyopathy (HCM), and channelopathy causing mutations is considerably high. Of note, we find that .38% of patients have compound or combined mutations and 12.8% have three or even more mutations. When comparing patients recruited in the eight participating European countries we find remarkably little differences in mutation frequencies and affected genes. Conclusion This is to our knowledge, the first study that comprehensively investigated the genetics of DCM in a large-scale cohort and across a broad gene panel of the known DCM genes. Our results underline the high analytical quality and feasibility of Next-Generation Sequencing in clinical genetic diagnostics and provide a sound database of the genetic causes of DCM. -

Formin Homology 2 Domain Containing 3 (FHOD3) Is a Genetic Basis for Hypertrophic Cardiomyopathy.

The genetic cause of hypertrophic cardiomyopathy remains unexplained in a substantial proportion of cases. Formin homology 2 domain containing 3 (FHOD3) may have a role in the pathogenesis of cardiac hypertrophy but has not been implicated in hypertrophic cardiomyopathy. This study sought to investigate the relation between FHOD3 mutations and the development of hypertrophic cardiomyopathy. FHOD3 was sequenced by massive parallel sequencing in 3,189 hypertrophic cardiomyopathy unrelated probands and 2,777 patients with no evidence of cardiomyopathy (disease control subjects). The authors evaluated protein-altering candidate variants in FHOD3 for cosegregation, clinical characteristics, and outcomes. The authors identified 94 candidate variants in 132 probands. The variants' frequencies were significantly higher in patients with hypertrophic cardiomyopathy (74 of 3,189 [2.32%]) than in disease control subjects (18 of 2,777 [0.65%]; p  FHOD3 is a novel disease gene in hypertrophic cardiomyopathy, accounting for approximately 1% to 2% of cases. The phenotype and the rate of cardiovascular events are similar to those reported in unselected cohorts. The FHOD3 gene should be routinely included in hypertrophic cardiomyopathy genetic testing panels

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field