scholarly journals A Novel Myosin Essential Light Chain Mutation Causes Hypertrophic Cardiomyopathy with Late Onset and Low Expressivity

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Paal Skytt Andersen ◽  
Paula Louise Hedley ◽  
Stephen P. Page ◽  
Petros Syrris ◽  
Johanna Catharina Moolman-Smook ◽  
...  

Hypertrophic cardiomyopathy (HCM) is caused by mutations in genes encoding sarcomere proteins. Mutations inMYL3, encoding the essential light chain of myosin, are rare and have been associated with sudden death. Both recessive and dominant patterns of inheritance have been suggested. We studied a large family with a 38-year-old asymptomatic HCM-affected male referred because of a murmur. The patient had HCM with left ventricular hypertrophy (max WT 21 mm), a resting left ventricular outflow gradient of 36 mm Hg, and left atrial dilation (54 mm). Genotyping revealed heterozygosity for a novel missense mutation, p.V79I, inMYL3. The mutation was not found in 300 controls, and the patient had no mutations in 10 sarcomere genes. Cascade screening revealed a further nine heterozygote mutation carriers, three of whom had ECG and/or echocardiographic abnormalities but did not fulfil diagnostic criteria for HCM. The penetrance, if we consider this borderline HCM the phenotype of the p.V79I mutation, was 40%, but the mean age of the nonpenetrant mutation carriers is 15, while the mean age of the penetrant mutation carriers is 47. The mutation affects a conserved valine replacing it with a larger isoleucine residue in the region of contact between the light chain and the myosin lever arm. In conclusion,MYL3mutations can present with low expressivity and late onset.

2013 ◽  
Vol 305 (4) ◽  
pp. H575-H589 ◽  
Author(s):  
Katarzyna Kazmierczak ◽  
Ellena C. Paulino ◽  
Wenrui Huang ◽  
Priya Muthu ◽  
Jingsheng Liang ◽  
...  

The functional consequences of the familial hypertrophic cardiomyopathy A57G (alanine-to-glycine) mutation in the myosin ventricular essential light chain (ELC) were assessed in vitro and in vivo using previously generated transgenic (Tg) mice expressing A57G-ELC mutant vs. wild-type (WT) of human cardiac ELC and in recombinant A57G- or WT-protein-exchanged porcine cardiac muscle strips. Compared with the Tg-WT, there was a significant increase in the Ca2+ sensitivity of force (ΔpCa50 ≅ 0.1) and an ∼1.3-fold decrease in maximal force per cross section of muscle observed in the mutant preparations. In addition, a significant increase in passive tension in response to stretch was monitored in Tg-A57G vs. Tg-WT strips indicating a mutation-induced myocardial stiffness. Consistently, the hearts of Tg-A57G mice demonstrated a high level of fibrosis and hypertrophy manifested by increased heart weight-to-body weight ratios and a decreased number of nuclei indicating an increase in the two-dimensional size of Tg-A57G vs. Tg-WT myocytes. Echocardiography examination showed a phenotype of eccentric hypertrophy in Tg-A57G mice, enhanced left ventricular (LV) cavity dimension without changes in LV posterior/anterior wall thickness. Invasive hemodynamics data revealed significantly increased end-systolic elastance, defined by the slope of the pressure-volume relationship, indicating a mutation-induced increase in cardiac contractility. Our results suggest that the A57G allele causes disease by means of a discrete modulation of myofilament function, increased Ca2+ sensitivity, and decreased maximal tension followed by compensatory hypertrophy and enhanced contractility. These and other contributing factors such as increased myocardial stiffness and fibrosis most likely activate cardiomyopathic signaling pathways leading to pathologic cardiac remodeling.


Author(s):  
С.С. Ниязова ◽  
Н.Н. Чакова ◽  
С.М. Комиссарова ◽  
М.А. Сасинович

Введение. Гипертрофическая кардиомиопатия (ГКМП) относится к наследственной патологии, основной причиной которой являются мутации в генах, кодирующих белковые компоненты миофибрильного аппарата кардиомиоцитов, при этом спектр этих генетических изменений имеет популяционные особенности. Целью данного исследования являлось определение спектра мутаций в генах, кодирующих саркомерные белки, у пациентов с ГКМП из Беларуси, а также изучение взаимосвязей между генотипом и фенотипическими проявлениями заболевания. Материалы и методы. В исследование были включены 340 неродственных пациентов с ГКМП, проживающих в Беларуси. Обнаружение мутаций в кодирующих последовательностях генов ACTC1, MYBPC3, MYH7, MYL2, MYL3, TNNI3, TNNT2, TNNС1 и TPM1 у 89 пациентов проводили методом высокопроизводительного секвенирования (NGS). Направленный поиск выявленных методом NGS генетических дефектов осуществлялся методом автоматического секвенирования по Сэнгеру, а также с использованием ПЦР-ПДРФ анализа. Результаты. У 51,7% пациентов методом NGS обнаружены мутации в генах: MYBPC3 (20,2%), MYH7 (16,9%), TPM1 (3,4%), ACTC1 (2,3%), MYL2 (1,1%) и TNNC1 (1,1%). У 6,7% индивидуумов встречались две (5,6%) или три (1,1%) замены. Обнаружены новые мутации p.Ala49Asn, p.Val1407Phe в гене MYH7; р.Tyr501Ser, р.Trp1007fs, р.Tyr1043*, р.Pro1066Arg, p.Arg1138fs, р.Pro1181Gln, р.Cys1202Arg в гене MYBPC3. Установлены часто встречающиеся мутации: р.Gln1233*, р.Ser871Alafs, комбинация р.Glu1265Val+р.Cys1266Arg, р.Gln401* и р.Trp1214Arg в гене MYBPC3, p.Arg403Trp, p.Arg663Cys, p.Arg663His, p.Ala729Pro, p.Glu924Lys и p.Glu1356Lys в гене MYH7. По данным ЭхоКГ-исследования носители мутаций в генах белков саркомера, особенно обладатели миссенс-мутаций в гене MYBPC3, имели более выраженную гипертрофию миокарда и раннюю манифестацию заболевания по сравнению с пациентами без мутаций в этих генах. Для носителей наиболее распространенной среди белорусских пациентов мутации р.Gln1233* характерны позднее начало заболевания, умеренная гипертрофия миокарда левого желудочка, частое развитие фибрилляции предсердий. Выводы. Распределение встречаемости мутаций в генах, кодирующих саркомерные белки, у пациентов с ГКМП из Беларуси не отличалось от других европейских популяций. 84,9% обнаруженных мутаций локализовано в генах MYBPC3 и MYH7. Background. Hypertrophic cardiomyopathy (HCM) is a hereditary pathology, the main cause of which is mutations in the genes encoding the protein components of the myofibril apparatus of cardiomyocytes, and the spectrum of these genetic changes has population features. The aim of the study was to determine the spectrum of mutations in the genes encoding sarcomeric proteins in patients with HCM from Belarus, as well as to study the association between the genotype and the phenotypic manifestations of the disease. Materials and methods. The study included 340 unrelated patients with HCM from Belarus. Mutation detection in the coding sequences of ACTC1, MYBPC3, MYH7, MYL2, MYL3, TNNI3, TNNT2, TNNС1 и TPM1 genes was performed by next generation sequencing (NGS) in 89 patients. The directed search for genetic defects detected by the NGS method was carried out by the automatic sequencing method using Sanger and PCR-RFLP analysis. Results. The NGS method allowed to detect mutations in the genes of 51,7% of patients: MYBPC3 (20,2%), MYH7 (16,9%), TPM1 (3,4%), ACTC1 (2,3%), MYL2 (1,1 %) and TNNC1 (1,1%). In 6,7% of individuals two (5,6%) or three (1,1%) substitutions were observed. New mutations were found: p.Ala49Asn, p.Val1407Phe in the MYH7 gene; p.Tyr501Ser, p.Trp1007fs, p.Tyr1043*, p.Pro1066Arg, p.Arg1138fs, p.Pro1181Gln, р.Cys1202Arg in the MYBPC3 gene. The most frequently occurring mutations were identified: p.Gln1233*, p.Ser871Alafs, the combination of the р.Glu1265Val + p.Cys1266Arg, R.Gln401*, and Trp1214Arg in the MYBPC3 gene, p.Glu924Lys and p.Glu1356Lys in the MYH7 gene. According to the ECG study, carriers of mutations in sarcomere protein genes, especially with missense mutations in the MYBPC3 gene, had more severe myocardial hypertrophy and early disease manifestation then patients without mutations in those genes. The p.Gln1233* mutation was the most common among Belarusian patients and characterized by late onset of the disease, mild left ventricular myocardial hypertrophy and the more frequent development of atrial fibrillation. Conclusions. In general, the distribution of mutations in the genes encoding sarcomeric proteins in patients with HCM from Belarus didn’t differ from other European populations. 84,9% of the detected mutations were localized in MYBPC3 and MYH7 genes.


2006 ◽  
Vol 291 (5) ◽  
pp. H2098-H2106 ◽  
Author(s):  
D. Dumka ◽  
J. Talent ◽  
I. Akopova ◽  
G. Guzman ◽  
D. Szczesna-Cordary ◽  
...  

Familial hypertrophic cardiomyopathy is a disease characterized by left ventricular and/or septal hypertrophy and myofibrillar disarray. It is caused by mutations in sarcomeric proteins, including the ventricular isoform of myosin regulatory light chain (RLC). The E22K mutation is located in the RLC Ca2+-binding site. We have studied transgenic (Tg) mouse cardiac myofibrils during single-turnover contraction to examine the influence of E22K mutation on 1) dissociation time (τ1) of myosin heads from thin filaments, 2) rebinding time (τ2) of the cross bridges to actin, and 3) dissociation time (τ3) of ADP from the active site of myosin. τ1 was determined from the increase in the rate of rotation of actin monomer to which a cross bridge was bound. τ2 was determined from the rate of anisotropy change of the recombinant essential light chain of myosin labeled with rhodamine exchanged for native light chain (LC1) in the cardiac myofibrils. τ3 was determined from anisotropy of muscle preloaded with a stoichiometric amount of fluorescent ADP. Cross bridges were induced to undergo a single detachment-attachment cycle by a precise delivery of stoichiometric ATP from a caged precursor. The times were measured in Tg-mutated (Tg-m) heart myofibrils overexpressing the E22K mutation of human cardiac RLC. Tg wild-type (Tg-wt) and non-Tg muscles acted as controls. τ1 was statistically greater in Tg-m than in controls. τ2 was shorter in Tg-m than in non-Tg, but the same as in Tg-wt. τ3 was the same in Tg-m and controls. To determine whether the difference in τ1 was due to intrinsic difference in myosin, we estimated binding of Tg-m and Tg-wt myosin to fluorescently labeled actin by measuring fluorescent lifetime and time-resolved anisotropy. No difference in binding was observed. These results suggest that the E22K mutation has no effect on mechanical properties of cross bridges. The slight increase in τ1 was probably caused by myofibrillar disarray. The decrease in τ2 of Tg hearts was probably caused by replacement of the mouse RLC for the human isoform in the Tg mice.


1990 ◽  
Vol 259 (6) ◽  
pp. H1681-H1687 ◽  
Author(s):  
R. J. Tomanek ◽  
M. R. Aydelotte ◽  
C. A. Butters

We tested the hypothesis that late-onset hypertension in middle-aged (15 mo) and senescent (24 mo) rats would adversely affect the coronary microvasculature. Morphometric analyses were performed on coronary capillaries and arterioles from rats with one-kidney, figure-8 renal wrap hypertension of 3-mo duration. Compared with control rats, wall-to-lumen ratios of arterioles with lumen diameters less than 25 microns were higher in the two hypertensive groups by approximately 30%; larger arterioles did not show consistent intergroup differences. A comparison of the two control groups revealed that wall-to-lumen ratio of arterioles with lumen diameters less than 50 microns tended to be greater in the senescent rats. Capillary numerical density was markedly reduced in the hypertensive animals of both age groups and caused an increase in the mean Krough cylinder radius and in the mean capillary domain. The latter increased by 28-63%; the largest increment occurred in the endomyocardium of the senescent group. A trend toward increased heterogeneity of capillary spacing was also noted in the hypertensive rats. The observed microvascular alterations occurred in the absence of an absolute increase in left ventricular mass but in the presence of cardiocyte hypertrophy. Thus the decrements in capillary numerical density are not only due to inadequate growth but reflect an absolute reduction in the number of these vessels associated with cardiocyte loss. It is concluded that late-onset hypertension in middle-aged and senescent rats is characterized by left ventricular wall remodeling that includes microvascular alterations that would be expected to limit maximal myocardial flow and O2 supply to the cardiocyte.


2002 ◽  
Vol 34 (7) ◽  
pp. 873-882 ◽  
Author(s):  
Jeanne James ◽  
Yan Zhang ◽  
Kathy Wright ◽  
Sra Witt ◽  
Elizabeth Glascock ◽  
...  

2014 ◽  
Vol 2014 ◽  
pp. 1-3
Author(s):  
Danny A. J. P. van de Sande ◽  
Jan Hoogsteen ◽  
Luc J. H. J. Theunissen

Hypertrophic cardiomyopathy (HCM) is a common inherited cardiovascular disease with prevalence of 0.2% in the population. More than 1000 mutations in more than 10 genes encoding for proteins of the cardiac sarcomere have been identified. Cardiac magnetic resonance imaging (CMR) is used to characterize left ventricular morphology with great precision in patients with HCM and it identifies unique structural abnormalities in patients with HCM. We present a case of a 56-year-old man who had positive family history of HCM who was a carrier of the genetic MYH-7 2770 G > C, exon 23 mutation. Transthoracic echocardiography showed thickening of the interventricular septum (16 mm) and in particular the basal septum. CMR confirmed the diagnosis of HCM in the anteroseptal myocardium with a thickness of 23 mm and also revealed large and deep myocardial crypts in the anterior wall. These myocardial crypts are rarely found in the so-called genotype positive and phenotype positive patients, as in our case. Also the crypts in this case are deeper and wider than those reported in other cases. So in conclusion, this case reveals an uncommon finding of a myocardial crypt at an unusual myocardial site with the unusual morphology in a patient with genotypic and phenotypic expression of hypertrophic cardiomyopathy.


2020 ◽  
Vol 7 (4) ◽  
pp. 1270
Author(s):  
Madhusudan Kummari ◽  
Amaresh Rao Malempati ◽  
Surya S. Gopal Palanki ◽  
Kaladhar Bomma

Background: The objective of the study was to evaluate effect of myectomy and its impact on survival for a period of one year and to identify the co-morbid conditions that would increase the risk of surgery.Methods: The study was conducted on the patients admitted in a single unit of department of cardiothoracic surgery, NIMS, Hyderabad during the period of 2014 to 2018. The study was a retrospective observational study. 21 patients were enrolled in the study after approval from institute ethics committee. All the patients between 7 to 70 years who underwent septal myectomy were included in the study.Results: Out of the 21 patients underwent modified Morrows myectomy 16 (76.2%) were male and 5 (23.8%) were female. The most common presenting symptom was dyspnea (81%), followed chest pain (76%), palpitations (62%) and syncope (38%). 5 (24%) patients had a family history of sudden cardiac death. Preoperative beta blockers were used by 15 (72%) patients. 11 patients had severe mitral regurgitation, out of which 8 patients underwent valve replacement and 3 underwent mitral valve repair. The mean preoperative left ventricular outflow tract obstruction gradient was 86.86 and the mean postoperative gradient was 23.47. 3 patients had implantable cardioverter defibrillator insertions. All patients had symptom relief.Conclusions: Surgical treatment of hypertrophic cardiomyopathy through transaortic septal myectomy is safe and effective method to relieve left ventricular outflow tract obstruction. Mitral valve replacement can be done for cases with structural defect of mitral valve. Early detection and intervention in patients with family history of sudden cardiac death would reduce the risk of death and ensure long term survival.


2021 ◽  
Vol 22 (Supplement_2) ◽  
Author(s):  
P Gac ◽  
B Kedzierski ◽  
K Truszkiewicz ◽  
R Poreba

Abstract Funding Acknowledgements Type of funding sources: None. Background The LGE (late gadolinium enhancement) sequence is a recognized classic tool for imaging focal myocardial injury. The T1-mapping sequence to assess native T1 myocardial time, post-contrast T1 time, and myocardial extracellular volume (ECV) is a widely studied tool for imaging focal and diffused myocardial injury. Purpose The aim of the study was to evaluate the native T1 time, the post-contrast T1 time and the myocardial extracellular volume in the T1-mapping sequence in patients with hypertrophic cardiomyopathy without focal LGE myocardial injury. Methods The study group consisted of 28 consecutive patients who met the criteria for diagnosis of hypertrophic cardiomyopathy without focal LGE myocardial injury (HCM group; mean age 52.17 ± 6.35 years). 28 patients without cardiomyopathy (CON group; mean age 51.76 ± 6.49 years) with similar anthropometric parameters were selected by the case-to-case method as a control group. All patients underwent 1.5 T cardiac magnetic resonance, including cinematographic sequences (CINE), LGE sequence and T1-mapping sequences before (native) and 20-minutes after intravenous administration of a paramagnetic agent (post-contrast). In the T1-mapping sequences, the mean T1 time of the whole myocardium (T1 whole myocardium) was assessed, as well as the T1 time in the basal layers (T1 basal), middle layers (T1 middle) and apical layers (T1 apical) of the myocardium. Moreover, the mean T1 time was assessed in the 16-segment myocardial AHA model (T1 segment 1-16). The extracellular volume of the myocardium was estimated in an analogous way. Results In CINE sequences, in the HCM group compared to the CON group, the end-diastolic thickness of the anterior part of interventricular septum, the end-diastolic thickness of the left ventricular posterior wall and the left ventricular mass index were significantly higher. The studied groups did not differ in left ventricular ejection fraction. In both groups, no foci of myocardial injury in the LGE sequence were found. There were no statistically significant differences in T1 times between the study groups. In the HCM group as compared to the CON group, the ECV whole myocardium, ECV basal, ECV apical and ECV segments 1-3, 8, 13-16 were statistically significantly higher. Conclusion Patients with hypertrophic cardiomyopathy without myocardium focal injury in the LGE sequence are characterized by higher myocardial ECV values, assessed in the T1-mapping sequence.


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