Search

Background: Mutations in the myosin heavy chain 7 ( MYH7) gene commonly cause cardiomyopathy but are less frequently associated with congenital heart defects. Methods: In this study, we describe a mutation in the MYH7 gene, c. 5754C > G; p. (Asn1918Lys), present in 15 probands and 65 family members. Results: Of the 80 carriers (age range 0-88 years), 46 (57.5%) had cardiomyopathy (mainly dilated cardiomyopathy (DCM)) and seven (8.8%) had a congenital heart defect. Childhood onset of cardiomyopathy was present in almost 10% of carriers. However, in only a slight majority (53.7%) was the left ventricular ejection fraction reduced and almost no arrhythmias or conduction disorders were noted. Moreover, only one carrier required heart transplantation and nine (11.3%) an implantable cardioverter defibrillator. In addition, the standardised mortality ratio for MYH7 carriers was not significantly increased. Whole exome sequencing in several cases with paediatric onset of DCM and one with isolated congenital heart defects did not reveal additional known disease-causing variants. Haplotype analysis suggests that the MYH7 variant is a founder mutation, and is therefore the first Dutch founder mutation identified in the MYH7 gene. The mutation appears to have originated in the western region of the province of South Holland between 500 and 900 years ago. Conclusion: Clinically, the p. (Asn1918Lys) mutation is associated with congenital heart defects and/or cardiomyopathy at young age but with a relatively benign course. [ABSTRACT FROM AUTHOR]

Purpose: Genetic variants causing aberrant premessenger RNA splicing are increasingly being recognized as causal variants in genetic disorders. In this study, we devise standardized practices for polymerase chain reaction (PCR)-based RNA diagnostics using clinically accessible specimens (blood, fibroblasts, urothelia, biopsy)., Methods: A total of 74 families with diverse monogenic conditions (31% prenatal-congenital onset, 47% early childhood, and 22% teenage-adult onset) were triaged into PCR-based RNA testing, with comparative RNA sequencing for 19 cases., Results: Informative RNA assay data were obtained for 96% of cases, enabling variant reclassification for 75% variants that can be used for genetic counseling (71%), to inform clinical care (32%) and prenatal counseling (41%). Variant-associated mis-splicing was highly reproducible for 28 cases with samples from ≥2 affected individuals or heterozygotes and 10 cases with ≥2 biospecimens. PCR amplicons encompassing another segregated heterozygous variant was vital for clinical interpretation of 22 of 79 variants to phase RNA splicing events and discern complete from partial mis-splicing., Conclusion: RNA diagnostics enabled provision of a genetic diagnosis for 64% of recruited cases. PCR-based RNA diagnostics has capacity to analyze 81.3% of clinically significant genes, with long amplicons providing an advantage over RNA sequencing to phase RNA splicing events. The Australasian Consortium for RNA Diagnostics (SpliceACORD) provide clinically-endorsed, standardized protocols and recommendations for interpreting RNA assay data., Competing Interests: Conflict of Interest Sandra T. Cooper is director of Frontier Genomics Pty Ltd (Australia). Sandra T. Cooper currently receives no consultancy fees or other remuneration for this role. Frontier Genomics Pty Ltd (Australia) has no existing financial relationships that will benefit from publication of these data. Samuel P. Strom is an employee and shareholder of Fulgent Genetics. Michael F. Buckley is an employee and shareholder of Invitae. The remaining coauthors declare no conflicts of interest., (Copyright © 2021. Published by Elsevier Inc.)

Aims: We sought to describe the clinical presentation, management, and 6-month outcomes in women with peripartum cardiomyopathy (PPCM) globally., Methods and Results: In 2011, >100 national and affiliated member cardiac societies of the European Society of Cardiology (ESC) were contacted to contribute to a global registry on PPCM, under the auspices of the ESC EURObservational Research Programme. These societies were tasked with identifying centres who could participate in this registry. In low-income countries, e.g. Mozambique or Burkina Faso, where there are no national societies due to a shortage of cardiologists, we identified potential participants through abstracts and publications and encouraged participation into the study. Seven hundred and thirty-nine women were enrolled in 49 countries in Europe (33%), Africa (29%), Asia-Pacific (15%), and the Middle East (22%). Mean age was 31 ± 6 years, mean left ventricular ejection fraction (LVEF) was 31 ± 10%, and 10% had a previous pregnancy complicated by PPCM. Symptom-onset occurred most often within 1 month of delivery (44%). At diagnosis, 67% of patients had severe (NYHA III/IV) symptoms and 67% had a LVEF ≤35%. Fifteen percent received bromocriptine with significant regional variation (Europe 15%, Africa 26%, Asia-Pacific 8%, the Middle East 4%, P < 0.001). Follow-up was available for 598 (81%) women. Six-month mortality was 6% overall, lowest in Europe (4%), and highest in the Middle East (10%). Most deaths were due to heart failure (42%) or sudden (30%). Re-admission for any reason occurred in 10% (with just over half of these for heart failure) and thromboembolic events in 7%. Myocardial recovery (LVEF > 50%) occurred only in 46%, most commonly in Asia-Pacific (62%), and least commonly in the Middle East (25%). Neonatal death occurred in 5% with marked regional variation (Europe 2%, the Middle East 9%)., Conclusion: Peripartum cardiomyopathy is a global disease, but clinical presentation and outcomes vary by region. Just under half of women experience myocardial recovery. Peripartum cardiomyopathy is a disease with substantial maternal and neonatal morbidity and mortality., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: journals.permissions@oup.com.)

The first human mutations in GATA6 were described in a cohort of patients with persistent truncus arteriosus, and the phenotypic spectrum has expanded since then. This study underscores the broad phenotypic spectrum by presenting two patients with de novo GATA6 mutations, both exhibiting complex cardiac defects, pancreatic, and other abnormalities. Furthermore, we provided a detailed overview of all published human genetic variation in/near GATA6 published to date and the associated phenotypes (n = 78). We conclude that the most common phenotypes associated with a mutation in GATA6 were structural cardiac and pancreatic abnormalities, with a penetrance of 87 and 60%, respectively. Other common malformations were gallbladder agenesis, congenital diaphragmatic hernia, and neurocognitive abnormalities, mostly developmental delay. Fifty-eight percent of the mutations were de novo, and these patients more often had an anomaly of intracardiac connections, an anomaly of the great arteries, and hypothyroidism, compared with those with inherited mutations. Functional studies mostly support loss-of-function as the pathophysiological mechanism. In conclusion, GATA6 mutations give a wide range of phenotypic defects, most frequently malformations of the heart and pancreas. This highlights the importance of detailed clinical evaluation of identified carriers to evaluate their full phenotypic spectrum., (© 2019 The Authors. American Journal of Medical Genetics Part A published by Wiley Periodicals, Inc.)

Background: Neuromuscular disorders (NMDs) are clinically and genetically heterogeneous. Accurate molecular genetic diagnosis can improve clinical management, provides appropriate genetic counseling and testing of relatives, and allows potential therapeutic trials., Objective: To establish the clinical utility of panel-based whole exome sequencing (WES) in NMDs in a population with children and adults with various neuromuscular symptoms., Methods: Clinical exome sequencing, followed by diagnostic interpretation of variants in genes associated with NMDs, was performed in a cohort of 396 patients suspected of having a genetic cause with a variable age of onset, neuromuscular phenotype, and inheritance pattern. Many had previously undergone targeted gene testing without results., Results: Disease-causing variants were identified in 75/396 patients (19%), with variants in the three COL6-genes (COL6A1, COL6A2 and COL6A3) as the most common cause of the identified muscle disorder, followed by variants in the RYR1 gene. Together, these four genes account for almost 25% of cases in whom a definite genetic cause was identified. Furthermore, likely pathogenic variants and/or variants of uncertain significance were identified in 95 of the patients (24%), in whom functional and/or segregation analysis should be used to confirm or reject the pathogenicity. In 18% of the cases with a disease-causing variant of which we received additional clinical information, we identified a genetic cause in genes of which the associated phenotypes did not match that of the patients. Hence, the advantage of panel-based WES is its unbiased approach., Conclusion: Whole exome sequencing, followed by filtering for NMD genes, offers an unbiased approach for the genetic diagnostics of NMD patients. This approach could be used as a first-tier test in neuromuscular disorders with a high suspicion of a genetic cause. With uncertain results, functional testing and segregation analysis are needed to complete the evidence.

Aims: The purpose of this study is to describe disease presentation, co-morbidities, diagnosis and initial therapeutic management of patients with peripartum cardiomyopathy (PPCM) living in countries belonging to the European Society of Cardiology (ESC) vs. non-ESC countries., Methods and Results: Out of 500 patients with PPCM entered by 31 March 2016, we report on data of the first 411 patients with completed case record forms (from 43 countries) entered into this ongoing registry. There were marked differences in socio-demographic parameters such as Human Development Index, GINI index on inequality, and Health Expenditure in PPCM patients from ESC vs. non-ESC countries (P < 0.001 each). Ethnicity was Caucasian (34%), Black African (25.8%), Asian (21.8%), and Middle Eastern backgrounds (16.4%). Despite the huge disparities in socio-demographic factors and ethnic backgrounds, baseline characteristics are remarkably similar. Drug therapy initiated post-partum included ACE inhibitors/ARBs and mineralocorticoid receptor antagonists with identical frequencies in ESC vs. non-ESC countries. However, in non-ESC countries, there was significantly less use of beta-blockers (70.3% vs. 91.9%) and ivabradine (1.4% vs. 17.1%), but more use of diuretics (91.3% vs. 68.8%), digoxin (37.0% vs. 18.0%), and bromocriptine (32.6% vs. 7.1%) (P < 0.001). More patients in non-ESC vs. ESC countries continued to have symptomatic heart failure after 1 month (92.3% vs. 81.3%, P < 0.001). Venous thrombo-embolic events, arterial embolizations, and cerebrovascular accidents were documented in 28 of 411 patients (6.8%). Neonatal death rate was 3.1%., Conclusion: PPCM occurs in women from different ethnic backgrounds globally. Despite marked differences in socio-economic background, mode of presentation was largely similar. Embolic events and persistent heart failure were common within 1 month post-diagnosis and required intensive, multidisciplinary management., (© 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.)

We report two unrelated patients with a multisystem disease involving liver, eye, immune system, connective tissue, and bone, caused by biallelic mutations in the neuroblastoma amplified sequence (NBAS) gene. Both presented as infants with recurrent episodes triggered by fever with vomiting, dehydration, and elevated transaminases. They had frequent infections, hypogammaglobulinemia, reduced natural killer cells, and the Pelger-Huët anomaly of their granulocytes. Their facial features were similar with a pointed chin and proptosis; loose skin and reduced subcutaneous fat gave them a progeroid appearance. Skeletal features included short stature, slender bones, epiphyseal dysplasia with multiple phalangeal pseudo-epiphyses, and small C1-C2 vertebrae causing cervical instability and myelopathy. Retinal dystrophy and optic atrophy were present in one patient. NBAS is a component of the synthaxin-18 complex and is involved in nonsense-mediated mRNA decay control. Putative loss-of-function mutations in NBAS are already known to cause disease in humans. A specific founder mutation has been associated with short stature, optic nerve atrophy and Pelger-Huët anomaly of granulocytes (SOPH) in the Siberian Yakut population. A more recent report associates NBAS mutations with recurrent acute liver failure in infancy in a group of patients of European descent. Our observations indicate that the phenotypic spectrum of NBAS deficiency is wider than previously known and includes skeletal, hepatic, metabolic, and immunologic aspects. Early recognition of the skeletal phenotype is important for preventive management of cervical instability., (© 2015 Wiley Periodicals, Inc.)

Background: The EURObservational Research Programme is a rolling programme of cardiovascular registries and surveys of the European Society of Cardiology (ESC). These registries will provide information on the nature of cardiovascular disease and its management. This manuscript provides an update on new literature on peripartum cardiomyopathy (PPCM), published since the 2010 Position Statement from the Heart Failure Association of the European Society of Cardiology Working Group on PPCM, and describes a new registry on this under-recognized condition. Peripartum cardiomyopathy is an idiopathic cardiomyopathy presenting with heart failure secondary to left ventricular systolic dysfunction towards the end of the pregnancy, or in the months following delivery, where no other cause for heart failure is found., Aims: The PPCM Registry aims to describe disease presentation, comorbidities, diagnostic and therapeutic management of patients with PPCM, as well as information on their offspring. Centres not only from ESC and ESC-affiliated countries, but from around the world, are encouraged to participate., Methods: A prospective registry on patients presenting with PPCM. At the time of writing, approximately 100 patients have been enrolled from 20 countries. All data entry is online via secure passwords and is supported by well-trained information technology personnel., Conclusion: The EURObservational Research Programme will allow a comparison of women from around the world, from different ethnic backgrounds, presenting with PPCM and will report on their 6 month and 12 month outcomes. The study aims to include 1000 patients and follow them for 1 year. New centres volunteering to participate in the study will be welcomed., (© 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.)

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterised by the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene on chromosome 9q34 or the TSC2 gene on chromosome 16p13.3. The TSC1 and TSC2 gene products, TSC1 and TSC2, interact to form a protein complex that inhibits signal transduction to the downstream effectors of the mammalian target of rapamycin (mTOR). Here we investigate the effects of putative TSC1 missense mutations identified in individuals with signs and/or symptoms of TSC on TSC1-TSC2 complex formation and mTOR signalling. We show that specific amino-acid substitutions close to the N-terminal of TSC1 reduce steady-state levels of TSC1, resulting in the activation of mTOR signalling and leading to the symptoms of TSC.

Mutations in ABCA1 uniformly decrease plasma HDL-cholesterol (HDL-C) and reduce cholesterol efflux, yet different mutations in ABCA1 result in different phenotypic effects in heterozygotes. For example, truncation mutations result in significantly lower HDL-C and apoliprotein A-I (apoA-I) levels in heterozygotes compared with nontruncation mutations, suggesting that truncation mutations may negatively affect the wild-type allele. To specifically test this hypothesis, we examined ABCA1 protein expression in response to 9-cis-retinoic acid (9-cis-RA) and 22-R-hydroxycholesterol (22-R-OH-Chol) in a collection of human fibroblasts representing eight different mutations and observed that truncation mutations blunted the response to oxysterol stimulation and dominantly suppressed induction of the remaining full-length allele to 5-10% of wild-type levels. mRNA levels between truncation and nontruncation mutations were comparable, suggesting that ABCA1 expression was suppressed at the protein level. Dominant negative activity of truncated ABCA1 was recapitulated in an in vitro model using transfected Cos-7 cells. Our results suggest that the severe reduction of HDL-C in patients with truncation mutations may be at least partly explained by dominant negative suppression of expression and activity of the remaining full-length ABCA1 allele. These data suggest that ABCA1 requires a physical association with itself or other molecules for normal function and has important pharmacogenetic implications for individuals with truncation mutations.

The authors have previously shown that individuals heterozygous for ABCA1 mutations have decreased high density lipoprotein cholesterol, increased triglycerides and an increased frequency of coronary artery disease (CAD), and that single nucleotide polymorphisms (SNPs) in the coding region of the ABCA1 gene significantly impact plasma lipid levels and the severity of CAD in the general population. They have now identified several SNPs in non-coding regions of ABCA1 which may be important for the appropriate regulation of ABCA1 expression (i.e. in the promoter, intron 1 and the 5' untranslated region), and have examined the phenotypic effects of these SNPs in the REGRESS population. Out of 12 SNPs, four were associated with a clinical outcome. A threefold increase in coronary events with an increased family history of CAD was evident for the G-191C variant. Similarly, the C69T SNP was associated with a twofold increase in events. In contrast, the C-17G was associated with a decrease in coronary events and the InsG319 was associated with less atherosclerosis. For all these SNPs, the changes in atherosclerosis and CAD occurred without detectable changes in plasma lipid levels. These data suggest that common variation in non-coding regions of ABCA1 may significantly alter the severity of atherosclerosis, without necessarily influencing plasma lipid levels.

Background: Low plasma HDL cholesterol (HDL-C) is associated with an increased risk of coronary artery disease (CAD). We recently identified the ATP-binding cassette transporter 1 (ABCA1) as the major gene underlying the HDL deficiency associated with reduced cholesterol efflux. Mutations within the ABCA1 gene are associated with decreased HDL-C, increased triglycerides, and an increased risk of CAD. However, the extent to which common variation within this gene influences plasma lipid levels and CAD in the general population is unknown., Methods and Results: We examined the phenotypic effects of single nucleotide polymorphisms in the coding region of ABCA1. The R219K variant has a carrier frequency of 46% in Europeans. Carriers have a reduced severity of CAD, decreased focal (minimum obstruction diameter 1.81+/-0.35 versus 1.73+/-0.35 mm in noncarriers, P:=0.001) and diffuse atherosclerosis (mean segment diameter 2.77+/-0.37 versus 2.70+/-0.37 mm, P:=0.005), and fewer coronary events (50% versus 59%, P:=0.02). Atherosclerosis progresses more slowly in carriers of R219K than in noncarriers. Carriers have decreased triglyceride levels (1.42+/-0.49 versus 1.84+/-0.77 mmol/L, P:=0.001) and a trend toward increased HDL-C (0.91+/-0.22 versus 0.88+/-0.20 mmol/L, P:=0.12). Other single nucleotide polymorphisms in the coding region had milder effects on plasma lipids and atherosclerosis., Conclusions: These data suggest that common variation in ABCA1 significantly influences plasma lipid levels and the severity of CAD.

We and others have recently identified mutations in the ABCA1 gene as the underlying cause of Tangier disease (TD) and of a dominantly inherited form of familial hypoalphalipoproteinemia (FHA) associated with reduced cholesterol efflux. We have now identified 13 ABCA1 mutations in 11 families (five TD, six FHA) and have examined the phenotypes of 77 individuals heterozygous for mutations in the ABCA1 gene. ABCA1 heterozygotes have decreased HDL cholesterol (HDL-C) and increased triglycerides. Age is an important modifier of the phenotype in heterozygotes, with a higher proportion of heterozygotes aged 30-70 years having HDL-C greater than the fifth percentile for age and sex compared with carriers less than 30 years of age. Levels of cholesterol efflux are highly correlated with HDL-C levels, accounting for 82% of its variation. Each 8% change in ABCA1-mediated efflux is predicted to be associated with a 0.1 mmol/l change in HDL-C. ABCA1 heterozygotes display a greater than threefold increase in the frequency of coronary artery disease (CAD), with earlier onset than unaffected family members. CAD is more frequent in those heterozygotes with lower cholesterol efflux values. These data provide direct evidence that impairment of cholesterol efflux and consequently reverse cholesterol transport is associated with reduced plasma HDL-C levels and increased risk of CAD.