MYH7 Research Articles

Novel phenotypic variant in the MYH7 spectrum due to a stop-loss mutation in the C-terminal region: a case report

BackgroundDefects of the slow myosin heavy chain isoform coding MYH7 gene primarily cause skeletal myopathies including Laing Distal Myopathy, Myosin Storage Myopathy and are also responsible for cardiomyopathies. Scapuloperoneal and limb-girdle muscle weakness, congenital fiber type disproportion, multi-minicore disease were also reported in connection of MYH7. Pathogeneses of the defects in the head and proximal rod region of the protein are well described. However, the C-terminal mutations of the MYH7 gene are less known. Moreover, only two articles describe the phenotypic impact of the elongated mature protein product caused by termination signal loss.Case presentationHere we present a male patient with an unusual phenotypic variant of early-onset and predominant involvement of neck muscles with muscle biopsy indicating myopathy and sarcoplasmic storage material. Cardiomyopathic involvements could not be observed. Sequencing of MYH7 gene revealed a stop-loss mutation on the 3-prime end of the rod region, which causes the elongation of the mature protein.ConclusionsThe elongated protein likely disrupts the functions of the sarcomere by multiple functional abnormalities. This elongation could also affect the thick filament degradation leading to protein deposition and accumulation in the sarcomere, resulting in the severe myopathy of certain axial muscles. The phenotypic expression of the detected novel MYH7 genotype could strengthen and further expand our knowledge about mutations affecting the structure of MyHCI by termination signal loss in the MYH7 gene.

A triple stranded G-quadruplex formation in the promoter region of human myosin β(Myh7) gene

Regulatory regions in human genome, enriched in guanine-rich DNA sequences have the propensity to fold into G-quadruplex structures. On exploring the genome for search of G-tracts, it was interesting to find that promoter of Human Myosin Gene (MYH7) contains a conserved 23-mer G-rich sequence (HM-23). Mutations in this gene are associated with familial cardiomyopathy. Enrichment of MYH7 gene in G-rich sequences could possibly play a critical role in its regulation. We used polyacrylamide gel electrophoresis (PAGE), UV-Thermal denaturation (UV-Tm) and Circular Dichroism (CD), to demonstrate the formation of a G-quadruplex by 23-mer G-rich sequence HM23 in promoter location of MYH7 gene. We observed that the wild G-rich sequence HM23 containing consecutive G5 stretch in two stacks adopt G-quadruplexes of diverse molecularity by involvement of four-strand, three-strand and two-strands with same parallel topology. Interestingly, the mutated sequence in the absence of continuous G5 stretch obstructs the formation of three-stranded G-quadruplex. We demonstrated that continuous G5 stretch is mandatory for the formation of a unique three-stranded G-quadruplex. Presence of various transcription factors (TF) in vicinity of the sequence HM23 leave fair possibility of recognition by TF binding sites, and so modulate gene expression. These findings may add on our understanding about the effect of base change in the formation of varied structural species in similar solution condition. This study may give insight about structural polymorphism arising due to recognition of non-Watson-Crick G-quadruplex structures by cellular proteins and designing structure specific molecules.

EP04.30: Fetal dilated cardiomyopathy: genetic susceptibility?

Fetal dilated cardiomyopathy (DCM) may occur as the end result of both intrinsic and extrinsic cardiac disease. We present a novel case associated with two MYH7 and DSG2 gene variants in the setting of maternal Coxsackie seropositivity. A 28 year old G4P3 with chronic hypertension presented at 31 weeks gestation for a routine growth scan. Her fetal echocardiogram at 24 weeks gestation was normal; however, repeat ultrasound demonstrated biventricular dilation, wall thickening and poor contractility (figure 1), but no hydrops. The patient reported a viral illness two weeks prior to presentation, and serum Coxsackie B titers were highly positive at 1:80. She was admitted for betamethasone administration and discharged after serial echocardiograms demonstrated stable ventricular dilation and improved function. She underwent Caesarean delivery at term for a vigorous 2860g female infant. Postnatal echo demonstrated mild right-sided dilation and low normal systolic function; however, on the fourth day of life the infant was readmitted with heart failure. Labs were notable for NT pro-BNP 614, CK 207, negative Coxsackie titers, negative metabolic panel, and two heterozygous variants of uncertain significance in MYH7 and DSG2 on microarray. The infant was started on digoxin therapy and at 4 months was developing appropriately. Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A novel MYH9 mutation in a beta thalassemia major patient with thrombocytopenia

Macrothrombocytopenia is a congenital autosomal dominant blood disorder characterized by increased platelet size and decreased number of circulating platelets (Althaus and Greinacher, 2009). Here, we report a 32year old beta thalassemia major patient admitted to the hospital for the evaluation of low thrombocyte count. In this study, we aimed to analyze mutations in MYH9 gene in our patient, we found a T to G nucleotide change at 3814 in exon 25, resulting in a transition of Serine to Alanine (p.S1195A) in MYH9 gene (Fig. 1) This mutation is reported for the first time in our population and not defined at Human Gene Mutation Database (HGMD) previously.

THE NEW GENOME VARIANTS IN RUSSIAN CHILDREN WITH GENETICALLY DETERMINED CARDIOMYOPATHIES REVEALED WITH MASSIVE PARALLEL SEQUENCING

Background: Cardiomyopathies in children are serious, continuously progressing myocardium diseases which are characterized by a variety of the causes, symptoms, implications, and high lethality. More than 400 genes that can cause hereditary heart and vessels diseases are described in scientific literature. The application of a high-performance method of massive parallel sequencing allows to conduct the investigation of genome extended targeted areas revealing the variants and analyzing them (bioinformatics) for pathogenicity.Aims: Identification of a genetic etiology of hereditary cardiomyopathies development in children’s population of the Russian Federation.Materials and methods: The research included 103 patients with various phenotypes of cardiomyopathies aged from 3 months up to 17 years 9 months who at the moment of examination were observed in the cardiology department and the department of recovery treatment with cardiovascular diseases in the NMRCCH. All patients were performed massive parallel sequencing analyzing the targeted areas of 404 genes which mutations lead to the development of heart and vessels hereditary diseases.Results: The diagnostic algorithm based on the method of a massive parallel sequencing was developed. 176 258 minor options were identified in the explored target areas of genome of 103 patients. An average number of the revealed nucleotide replacements different from the reference sequence was 1711. We observed that about 40% of all variants founded by our means were found in MYH7, MYBPC3, TTN, MYH6, SCN5A, DSC2 and TPM1 genes. Bioinformatics analysis allowed revealing 68 novel genome variants associated with cardiomyopathy development. The reliable association of carriage of pathogenic option in MYBPC3 gene with development of hypertrophic cardiomyopathy in the Russian children was found.Conclusions: The application of the offered algorithm allowed establishing laboratory diagnoses to 99 (96.1%) patients out from 103 investigated subjects including the syndromal and non-syndromal forms of heart and vessels hereditary diseases which showed a cardiomyopathy phenotype.

Finding the candidate sequence variants for diagnosis of hypertrophic cardiomyopathy in East Slovak patients.

Hypertrophic cardiomyopathy is a heterogeneous myocardial disease. Mutations appearing in several genes might be a potential cause of the disease. The aim of the study was to analyze selected exons of the sarcomeric and non-sarcomeric genes, with the purpose to identify potential candidate genetic variants and to understand etiopathogenetic mechanisms of hypertrophic cardiomyopathy in East Slovak patients. This study recruited 23 unrelated patients with hypertrophic cardiomyopathy, namely, 13 men and 10 women (mean age of 58.09±15.82years) and 25 healthy controls in order to determine the candidate sequence variants, in the selected exons of six cardiomyopathy genes (MYBPC3, MYH7, NEBL, SCN5A, TNNI3, TNNT2), by conventional capillary-based Sanger sequencing method and standard protocols. Molecular genetic results confirmed the presence of 43 sequence variants in the selected exons of six cardiomyopathy genes, 58.14% of detected variants were novel. The majority of detected sequence variants were confirmed within exon 23 of MYH7 gene. Only 11 genetic alterations were predicted to be potentially pathogenic. In our study, we identified known and novel sequence variants in 23 unrelated patients with hypertrophic cardiomyopathy, but we did not observe any strong mutation hotspot. The results of our study assumed that exon 23 of MYH7 gene can be in potential affinity to hypertrophic cardiomyopathy in our cohort of patients. The sequence variants identified in this study may be further investigated in order to determine their functions in disease pathogenesis and improve management, diagnosis, and treatment in Slovak patients.

Vestigial-like 2 contributes to normal muscle fiber type distribution in mice

Skeletal muscle is composed of heterogeneous populations of myofibers that are classified as slow- and fast-twitch fibers. The muscle fiber-type is regulated in a coordinated fashion by multiple genes, including transcriptional factors and microRNAs (miRNAs). However, players involved in this regulation are not fully elucidated. One of the members of the Vestigial-like factors, Vgll2, is thought to play a pivotal role in TEA domain (TEAD) transcription factor-mediated muscle-specific gene expression because of its restricted expression in skeletal muscles of adult mice. Here, we generated Vgll2 null mice and investigated Vgll2 function in adult skeletal muscles. These mice presented an increased number of fast-twitch type IIb fibers and exhibited a down-regulation of slow type I myosin heavy chain (MyHC) gene, Myh7, which resulted in exercise intolerance. In accordance with the decrease in Myh7, down-regulation of miR-208b, encoded within Myh7 gene and up-regulation of targets of miR-208b, Sox6, Sp3, and Purβ, were observed in Vgll2 deficient mice. Moreover, we detected the physical interaction between Vgll2 and TEAD1/4 in neonatal skeletal muscles. These results suggest that Vgll2 may be both directly and indirectly involved in the programing of slow muscle fibers through the formation of the Vgll2-TEAD complex.

Intrinsic MYH7 expression regulation contributes to tissue level allelic imbalance in hypertrophic cardiomyopathy

HCM, the most common inherited cardiac disease, is mainly caused by mutations in sarcomeric genes. More than a third of the patients are heterozygous for mutations in the MYH7 gene encoding for the β-myosin heavy chain. In HCM-patients, expression of the mutant and the wildtype allele can be unequal, thus leading to fractions of mutant and wildtype mRNA and protein which deviate from 1:1. This so-called allelic imbalance was detected in whole tissue samples but also in individual cells. There is evidence that the severity of HCM not only depends on the functional effect of the mutation itself, but also on the fraction of mutant protein in the myocardial tissue. Allelic imbalance has been shown to occur in a broad range of genes. Therefore, we aimed to examine whether the MYH7-alleles are intrinsically expressed imbalanced or whether the allelic imbalance is solely associated with the disease. We compared the expression of MYH7-alleles in non-HCM donors and in HCM-patients with different MYH7-missense mutations. In the HCM-patients, we identified imbalanced as well as equal expression of both alleles. Also at the protein level, allelic imbalance was determined. Most interestingly, we also discovered allelic imbalance and balance in non-HCM donors. Our findings therefore strongly indicate that apart from mutation-specific mechanisms, also non-HCM associated allelic-mRNA expression regulation may account for the allelic imbalance of the MYH7 gene in HCM-patients. Since the relative amount of mutant mRNA and protein or the extent of allelic imbalance has been associated with the severity of HCM, individual analysis of the MYH7-allelic expression may provide valuable information for the prognosis of each patient.

Hypoxia favors myosin heavy chain beta gene expression in an Hif-1alpha-dependent manner

The potentiation of the naturally limited regenerative capacity of the heart is dependent on an understanding of the mechanisms that are activated in response to pathological conditions such as hypoxia. Under these conditions, the expression of genes suggested to support cardiomyocyte survival and heart adaptation is triggered. Particularly important are changes in the expression of myosin heavy chain (MHC) isoforms. We propose here that alterations in the expression profiles of MHC genes are induced in response to hypoxia and are primarily mediated by hypoxia inducible factor (HIF). In in vitro models of mouse embryonic stem cell-derived cardiomyocytes, we showed that hypoxia (1% O2) or the pharmacological stabilization of HIFs significantly increased MHCbeta (Myh7) gene expression. The key role of HIF-1alpha is supported by the absence of these effects in HIF-1alpha-deficient cells, even in the presence of HIF-2alpha. Interestingly, ChIP analysis did not confirm the direct interaction of HIF-1alpha with putative HIF response elements predicted in the MHCalpha and beta encoding DNA region. Further analyses showed the significant effect of the mTOR signaling inhibitor rapamycin in inducing Myh7 expression and a hypoxia-triggered reduction in the levels of antisense RNA transcripts associated with the Myh7 gene locus. Overall, the recognized and important role of HIF in the regulation of heart regenerative processes could be highly significant for the development of novel therapeutic interventions in heart failure.

Taxonomic review of dwarf species of Eumicrotremus (Actinopterygii: Cottoidei: Cyclopteridae) with descriptions of two new species from the western North Pacific

A taxonomic review of the dwarf species of the genus Eumicrotremus (Actinopterygii: Cottoidei: Cyclopteridae), previously recognized as belonging to Lethotremus, established the existence of three species, viz. Eumicrotremus awae (Jordan and Snyder, 1902), Eumicrotremus uenoi sp. nov., and Eumicrotremus jindoensis sp. nov., from the western North Pacific. Eumicrotremus awae, known from the Pacific coast of Honshu Is. (Chiba southward to Mie), is characterized by the absence of spiny tubercles or fleshy papillae on the body, the anterior three mandibular pores each with a barbel-like tube, interorbital and suborbital pores usually absent, the opercular flap rounded, many papillae present on the ventral disk and the caudal-fin relatively short, 21.0–30.5% of SL (standard length). Eumicrotremus uenoi, known from the western coast of Honshu Is. and the southern coast of Korean Peninsula, is characterized by the absence of spiny tubercles or fleshy papillae on the body (or weak if present), the anterior three mandibular pores each with a barbel-like tube, interorbital and suborbital pores usually present, the opercular flap rounded, the ventral disk with many papillae and the caudal-fin relatively short, 19.5–31.4% of SL. Eumicrotremus jindoensis, known from the southwestern coast of Korean Peninsula, and the coasts of Yellow Sea, is characterized by a smooth soft body, triangular opercular flap, absence of papillae on the ventral disk and a long caudal fin, 32.7–42.1% of SL. Sequence variations of the mictochondrial DNA cytochrome c oxidase subunit I (mtDNA COI) and the nuclear myh6 genes supported the validity of the three species.

Genetic analysis of a pedigree affected with inherited thrombocytopenia caused by a novel mutation of MYH9 gene

To study genetic mutations and clinical features of a pedigree affected with MYH9-related disorders from Guangxi. Blood platelets were counted with a hemocytometer. Blood smear was carried out to detect the inclusion body in peripheral blood neutrophils. DNA and mRNA samples were extracted from blood samples from the members of the pedigree. Fragments of the MYH9 gene were amplified with PCR and directly sequenced. The affected individuals presented with a triad of giant platelets, decreased platelet count and inclusion bodies in the neutrophils with variable expressivity. A heterozygous deletional mutation (c.5803delG) in exon 41 of the MYH9 gene was found in all of the 8 affected individuals, which led to a frame-shift and change of 26 amino acids at the C-end of the tail domain of nonmuscle myosin heavy chain IIA (NMMHC-IIA) (p.Ala1935Profs*12). The same mutation was not found among healthy members of the pedigree. The c.5803delG mutation probably underlies the MYH9-related disorders in this pedigree. The mutation has altered the C-end of the tail domain of the NMMHC-IIA protein, resulting in mild clinical symptoms in the affected individuals.

A comparative study of mutation screening of sarcomeric genes (MYBPC3, MYH7, TNNT2) using single gene approach versus targeted gene panel next generation sequencing in a cohort of HCM patients in Egypt

BackgroundNGS enables simultaneous sequencing of large numbers of associated genes in genetic heterogeneous disorders, in a more rapid and cost-effective manner than traditional technologies. However there have been limited direct comparisons between NGS and more established technologies to assess the sensitivity and false negative rates of this new approach. The scope of the present manuscript is to compare variants detected in MYBPC3, MYH7 and TNNT2 genes using the stepwise dHPLC/Sanger versus targeted NGS. MethodsIn this study, we have analysed a group of 150 samples of patients from the Bibliotheca Alexandrina-Aswan Heart Centre National HCM program. The genetic testing was simultaneously undertaken by high throughput denaturing high-performance liquid chromatography (dHPLC) followed by Sanger based sequencing and targeted next generation deep sequencing using panel of inherited cardiac genes (ICC). The panel included over 100 genes including the 3 sarcomeric genes. Analysis of the sequencing data of the 3 genes was undertaken in a double blinded strategy. ResultsNGS analysis detected all pathogenic and likely pathogenic variants identified by dHPLC (50 in total, some samples had double hits). There was a 0% false negative rate for NGS based analysis. Nineteen variants were missed by dHPLC and detected by NGS, thus increasing the diagnostic yield in this co- analysed cohort from 22.0% (33/150) to 31.3% (47/150).Of interest to note that the mutation spectrum in this Egyptian HCM population revealed a high rate of homozygosity in MYBPC3 and MYH7 genes in comparison to other population studies (6/150, 4%). None of the homozygous samples were detected by dHPLC analysis. ConclusionNGS provides a useful and rapid tool to allow panoramic screening of several genes simultaneously with a high sensitivity rate amongst genes of known etiologic role allowing high throughput analysis of HCM patients and relevant control series in a less characterised population.

75 Inherited left ventricular non-compaction in spontaneous monochorionic diamniotic twin pregnancy

IntroductionPregnancy in Left Ventricular Non-Compaction (LVNC) can increase the risk of heart failure, arrhythmias and systemic embolic events. LVNC carries an autosomal dominant trait and incomplete penetrance. This case study...

Cellular force assay detects altered contractility caused by a nephritis-associated mutation in nonmuscle myosin IIA.

Recent progress in understanding the essential roles of mechanical forces in regulating various cellular processes expands the field of biology to one where interdisciplinary approaches with engineering techniques become indispensable. Contractile forces or contractility-inherently present in proliferative cells due to the activity of ubiquitous nonmuscle myosin II (NMII)-are one of such mechano-regulators, but because NMII works downstream of diverse signaling pathways, it is often difficult to predict how the inherent cellular forces change upon perturbations to particular molecules. Here, we determine whether the contractility of individual cells is upregulated or downregulated based on an assay analyzing specific deformations of silicone gel substrates. We focus on the effect of mutations in the human MYH9 gene that encodes NMIIA, which have been implicated in the pathogenesis of various diseases including nephritis. Our assay equipped with a high-throughput data analysis capability reveals that a point mutation of E1841K but not I1816V significantly reduces the magnitude of the endogenous forces of human embryonic kidney (HEK293) cells. Given the increasingly recognized roles of the endogenous forces as a critical mechano-regulator as well as that no apparent morphological changes were induced to cells even by introducing the mutations, our findings suggest a possibility that the detected reduction in the force magnitude at the individual cellular level may underlie the pathogenesis of the kidney disease.

Steps toward Maturation of Embryonic Stem Cell-Derived Cardiomyocytes by Defined Physical Signals.

SummaryCardiovascular disease remains a leading cause of mortality and morbidity worldwide. Embryonic stem cell-derived cardiomyocytes (ESC-CMs) may offer significant advances in creating in vitro cardiac tissues for disease modeling, drug testing, and elucidating developmental processes; however, the induction of ESCs to a more adult-like CM phenotype remains challenging. In this study, we developed a bioreactor system to employ pulsatile flow (1.48 mL/min), cyclic strain (5%), and extended culture time to improve the maturation of murine and human ESC-CMs. Dynamically-cultured ESC-CMs showed an increased expression of cardiac-associated proteins and genes, cardiac ion channel genes, as well as increased SERCA activity and a Raman fingerprint with the presence of maturation-associated peaks similar to primary CMs. We present a bioreactor platform that can serve as a foundation for the development of human-based cardiac in vitro models to verify drug candidates, and facilitates the study of cardiovascular development and disease.

Mutations in Hotspot Region of MYH7 Gene Exon 23 Associated with Restrictive Cardiomyopathy

Restrictive cardiomyopathy (RCM) is characterized by restrictive filling of the ventricles. The association between the variable expressivity and age at onset of disease and disease complexity with double and compound heterozygous state is associated with severity of disease phenotype in recent reports. Sharing of variants of sarcomere genes across cardiomyopathies has implication in clinical expression of different clinical phenotypes. The present study reports Sanger DNA sequencing of MYH7 gene, exon 23 from 30 unrelated RCM patients and 15 primary relatives from sporadic families with the hypothesis that RCM has common etiology with hypertrophic cardiomyopathy (HCM). Rare variant E949K and a de novo compound heterozygous mutation (p.E902K and p.D906N), in two RCM patients with early onset and no ventricular hypertrophy were found. These variants wereabsent in 50 dilated cardiomyopathy, 50 HCM patients and 15 primary relatives screened. The present report of rare and compound heterozygosity cases will further provide basis for the complexity and variable expressivity of phenotypes in patients in such complex diseases. The possible reasons for this phenotypic heterogeneity would be the presence of any other mutations in same chromosome or in different chromosome which is modifying the outcome of the causal mutation.

DNA Methylation Regulates Gene Expression in Intracranial Aneurysms.

Different gene expression profiles are observed in intracranial aneurysm tissues. Understanding these genes and what regulates their expression will provide insight into the pathogenesis of intracranial aneurysms. We investigated whether differences in DNA methylation regulate gene expression in intracranial aneurysms. We compared 20 intracranial aneurysm tissue specimens with 20 matched specimens from the superficial temporal artery as controls. We identified the gene expression profiles in these samples using the GeneChip Human U133 Plus 2.0 array and evaluated DNA methylation modifications using the Infinium HumanMethylation450 BeadChip Kit. A total of 11,022 differentially methylated sites between aneurysm tissues and matched control tissues were identified, and 2142 differentially expressed gene transcripts were detected based on the 2 gene expression profiles. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses and verification analysis showed that the MYH11, LIFR, and TLR4 genes were associated with the occurrence and development of intracranial aneurysms. These genes mainly encode cell adhesion molecules or are involved in the NF-κB, JAK-STAT, and ERK/JNK signaling pathways. In the development of intracranial aneurysms, DNA methylation plays an important role in the regulation of genetic expression involved in immune and inflammatory reactions, cell function, cell maintenance, and cell signal transduction.

Novel mutation in MYH7 gene causing scapuloperoneal syndrome (P4.122)

Novel mutation in MYH7 gene causing scapuloperoneal syndrome (P4.122)

Su2051 - Human Transcriptome Array Reveals Association of Spliced Transcripts of GAS5 and MYH9 Genes and Aberrantly Expressed Small Nuclear RNA in Oncogenic Transformation of Chronic Pancreatitis to Pancreatic Cancer

Su2051 - Human Transcriptome Array Reveals Association of Spliced Transcripts of GAS5 and MYH9 Genes and Aberrantly Expressed Small Nuclear RNA in Oncogenic Transformation of Chronic Pancreatitis to Pancreatic Cancer

Rare CBFB-MYH11 cryptic rearrangement in acute myeloid leukemia with ins(16)(p13.1q22q22)

<p>Acute myeloid leukemia (AML) with <em>CBFB-MYH11</em> fusion gene is almost always associated with either inv(16)(p13.1q22) or t(16;16)(p13.1;q22). Only a few variants leading to formation of this chimeric gene have been reported. In this report, we describe a novel type of <em>CBFB-MYH11</em> fusion variant generated by an insertion of <em>CBFB</em> into the <em>MYH11</em> gene, which is identifiable by fluorescence <em>in situ</em> hybridization (FISH).</p>