Association between clinical phenotypes of hypertrophic cardiomyopathy and Ca2+ gene variation gene variation / 中华心血管病杂志

Objective: To observe the association between clinical phenotypes of hypertrophic cardiomyopathy (HCM) patients and a rare calcium channel and regulatory gene variation (Ca2+ gene variation) and to compare clinical phenotypes of HCM patients with Ca2+ gene variation, a single sarcomere gene variation and without gene variation and to explore the influence of rare Ca2+ gene variation on the clinical phenotypes of HCM. Methods: Eight hundred forty-two non-related adult HCM patients diagnosed for the first time in Xijing Hospital from 2013 to 2019 were enrolled in this study. All patients underwent exon analyses of 96 hereditary cardiac disease-related genes. Patients with diabetes mellitus, coronary artery disease, post alcohol septal ablation or septal myectomy, and patients who carried sarcomere gene variation of uncertain significance or carried>1 sarcomere gene variation or carried>1 Ca2+ gene variation, with HCM pseudophenotype or carrier of ion channel gene variations other than Ca2+ based on the genetic test results were excluded. Patients were divided into gene negative group (no sarcomere or Ca2+ gene variants), sarcomere gene variation group (only 1 sarcomere gene variant) and Ca2+ gene variant group (only 1 Ca2+ gene variant). Baseline data, echocardiography and electrocardiogram data were collected for analysis. Results: A total of 346 patients were enrolled, including 170 patients without gene variation (gene negative group), 154 patients with a single sarcomere gene variation (sarcomere gene variation group) and 22 patients with a single rare Ca2+ gene variation (Ca2+ gene variation group). Compared with gene negative group, patients in Ca2+ gene variation group had higher blood pressure and higher percentage of family history of HCM and sudden cardiac death (P<0.05); echocardiographic results showed that patients in Ca2+ gene variation group had thicker ventricular septum ((23.5±5.8) mm vs. (22.3±5.7) mm, P<0.05); electrocardiographic results showed that patients in Ca2+ gene variation group had prolonged QT interval ((416.6±23.1) ms vs. (400.6±47.2) ms, P<0.05) and higher RV5+SV1 ((4.51±2.26) mv vs. (3.50±1.65) mv, P<0.05). Compared with sarcomere gene variation group, patients in Ca2+ gene variation group had later onset age and higher blood pressure (P<0.05); echocardiographic results showed that there was no significant difference in ventricular septal thickness between two groups; patients in Ca2+ gene variation group had lower percentage of left ventricular outflow tract pressure gradient>30 mmHg (1 mmHg=0.133 kPa, 22.8% vs. 48.1%, P<0.05) and the lower early diastolic peak velocity of the mitral valve inflow/early diastolic peak velocity of the mitral valve annulus (E/e') ratio ((13.0±2.5) vs. (15.9±4.2), P<0.05); patients in Ca2+ gene variation group had prolonged QT interval ((416.6±23.1) ms vs. (399.0±43.0) ms, P<0.05) and lower percentage of ST segment depression (9.1% vs. 40.3%, P<0.05). Conclusion: Compared with gene negative group, the clinical phenotype of HCM is more severe in patients with rare Ca2+ gene variation; compared with patients with sarcomere gene variation, the clinical phenotype of HCM is milder in patients with rare Ca2+ gene variation.

Clinical and genetic characteristics of different types of non-obstructive hypertrophic cardiomyopathy / 中华心血管病杂志

Objective: To analyze the clinical and genetic characteristics of clinical subtypes of non-obstructive hypertrophic cardiomyopathy (HCM). Methods: It was a cohort study. Patients with non-obstructive HCM admitted to Fuwai Hospital, Chinese Academy of Medical Sciences, from January 1999 to April 2019 were enrolled. According to the characteristics of cardiac morphology and function shown by echocardiography, the patients were divided into common type, dilated type, restricted type and reduced ejection fraction type. The clinical data of the patients were recorded, and 8 sarcomere pathogenic genes were screened by full exon sequencing or panel sequencing. Patienst were followed up and cardiovascular endpoint events were recorded. Results: A total of 815 patients with non-obstructive HCM were enrolled, including 27 (3.3%) restricted type, 51 (6.3%) dilated type, 30 (3.7%) reduced ejection fraction type and 707 (86.7%) common type. A total of 704 out of 815 patients underwent genetic testing. Among them, 299 (42.5%) patients carried at least 1 sarcomere gene mutation. MYBPC3 and MYH7 mutation accounted for 42.1% (126/299) and 35.8% (107/299) respectively. 66.7% (16/24) of the patients with restricted type carried sarcomere gene mutation, which was higher than that in patients with dilated type (36.4% (16/44)) and in common type (41.5% (250/602), P=0.015). Among the patients with reduced ejection fraction, 56.7% (17/30) patients carried sarcomere gene mutations, 23.3% (7/30) carried multiple sarcomere mutations, which was higher than that in restricted type (8.3% (2/24)), in dilated type (9.1% (4/44)) and in common type 4.2% ((24/577), P<0.001). MYH7 and MYBPC3 were the main mutation gene types of all clinical subtypes, and the genotypes were similar among groups (all P>0.05). Seven hundred and three out 815 patients were followed up for 2.9 (1.4, 4.0) years. There were 53(7.5%) cardiovascular death. Cardiovascular death occurred in 5.0% (29/578) patients with common type, 13.0% (3/23) patients with restricted type, 16.3% (7/43) patients with dilated type and 46.7% (14/30) patients with decreased ejection fraction. Univariate Cox proportional hazards model analysis showed that the risk of cardiovascular death in patients with restricted, dilated and reduced ejection fraction type was higher than that in patients with common type (P<0.001). After adjusting for gender, age of onset, body mass index, history of hypertension, coronary heart disease and diabetes, multivariate Cox proportional hazards model analysis showed that the HR of cardiovascular death in patients with restricted, dilated and reduced ejection fraction type were 5.454 (95%CI 1.137-26.157, P=0.034) and 6.597 (95%CI 1.632-26.667, P=0.008) and 9.028 (95%CI 2.201-37.039, P=0.002) respectively, as compared to patients with common type. Conclusions: Most of the patients with non-obstructive HCM are common type, featured by mild clinical manifestations and good prognosis. Although the proportion of restricted type and dilated type is relatively low, and cardiac systolic function is mostly preserved, the clinical phenotype and prognosis of these patients are similarly severe and poor as patients with reduced ejection fraction. The genotypes are similar in different clinical subtypes, but the proportion of patients with sarcomere gene mutation is higher in restricted type, and the proportion of patients with multiple sarcomere gene mutation is higher in decreased ejection fraction type.

Genes frequently associated with sudden death in primary hypertrophic cardiomyopathy / Genes frecuentemente asociados con muerte súbita en miocardiopatía hipertrófica primaria

Abstract Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy without apparent cardiac justification. Sudden cardiac death may be the first manifestation of the disease. It occurs mainly in adulthood and can be seen in childhood and adolescence where genetic origin predominates. Primary HCM (“familial”) is inherited in an autosomal dominant pattern in the 25 subtypes informed in Online Mendelian Inheritance in Man. The proteins encoded by the mutated genes are part of the sarcomere in the cardiac cells, being the thick filament the most frequently affected, with the worst prognosis. In the present article, we describe the Mendelian inheritance of the disease and the two most associated genes with sudden death: MYBPC3 and MYH7.

Resumen La miocardiopatía hipertrófica (MCH) es el aumento de grosor de la pared ventricular izquierda no relacionada con otras alteraciones cardíacas. Es una enfermedad que puede presentar como primera manifestación clínica la muerte súbita y de ahí su relevancia clínica. Aunque se presenta sobre todo en la edad adulta, puede aparecer durante la infancia y adolescencia, en las que predominan los casos de origen hereditario. La MCH primaria, de causa genética, muestra en particular un patrón de herencia autosómico dominante en los 25 subtipos reconocidos en OMIM (Online Mendelian Inheritance in Man). Las proteínas codificadas por los genes mutantes forman parte del sarcómero en células musculares cardíacas, y las variantes patogénicas de filamentos gruesos son las de mayor frecuencia y peor pronóstico. En este artículo se describen la herencia mendeliana de la enfermedad y la relación con muerte súbita de los genes más frecuentemente encontrados en ella: MYBPC3 y MYH7.

The role of three-dimensional speckle tracking imaging derived parameters on predicting outcome of hypertrophic cardiomyopathy patients with MYH7 mutations / 中华心血管病杂志

Objective: To evaluate the cardiac functional changes in hypertrophic cardiomyopathy(HCM) patients with β-myosin heavy chain gene (MYH7) mutations by three-dimensional (3D) speckle tracking imaging(3D-STI) and conventional echocardiography modalities, and then to explore the potential predictors of adverse cardiovascular events in these patients. Methods: A consecutive series of 192 HCM patients admitted in our center from October 2014 to October 2016 were genetically screened to identify MYH7 mutations in this retrospective study. A total of 43 HCM patients with MYH7 mutations were enrolled. The patients were divided into events group(n=13) and no event group(n=30) according to the presence or absence of adverse cardiovascular events(primary and secondary endpoints). All patients were followed up to January 2019 after comprehensive evaluation of 3D-STI, two-dimensional and Doppler echocardiography. The adverse cardiovascular events were recorded. Results: The median follow up time was 1 012 (812, 1 330) days. During follow-up, 13 patients (30.2%) reached endpoints: 6 cases of the primary endpoints(2 cases of sudden cardiac death(SCD), 3 cases of survival after defibrillation, and 1 case of appropriate implantable cardioverter-defibrillator(ICD) discharge); 7 cases of the second endpoints(5 cases of heart failure hospitalization, 1 case of syncope and cardioversion due to supraventricular tachycardia, and 1 case of end-stage HCM). Patients with adverse cardiovascular events had higher prevalence of syncope and risk of SCD, enlarged left atrial volume index(LAVI) and reduced 3D left ventricular global longitudinal train (3D-GLS), as compared to those without adverse events(all P<0.05). The multivariate Cox regression analysis showed that reduced 3D-GLS(HR=0.814, 95%CI 0.663-0.999, P=0.049) was an independent predictor for adverse cardiovascular events. The cutoff value of 3D-GLS≤13.67% was linked with significantly increased risk of adverse cardiovascular events in this patient cohort(AUC=0.753, 95%CI 0.558-0.948, sensitivity 86%, specificity 69%, P<0.05). The Kaplan-Meier analysis indicated that the patients with the 3D-GLS≤ 13.67% faced higher risk of death than those with 3D-GLS>13.67%. Conclusion: 3D-GLS is useful on predicting adverse cardiovascular events in HCM patients with MYH7 mutations.

Avaliação ecocardiográfica da insuficiência mitral em pacientes com cardiomiopatia hipertrófica / Ecocardiographic evaluation of mitral insufficiency in patients with hypertrophic cardiomyopathy

A cardiomiopatia hipertrófica é uma doença de origem genética, que afeta milhares de pessoas em todo o mundo.Objetivos: Avaliar a presença de regurgitação mitral em pacientes com cardiomiopatia hipertrófica, bem como sua relação com variáveis ecodopplercardiográficas do ventrículo esquerdo. A disfunção de valva mitral encontradas nesses pacientes mostra-se um dado de extrema relevância, visto que é capaz de predizer a sobrevida e a taxa de mortalidade dos enfermos acometidos pela cardiomiopatia hipertrófica.Métodos: Foram avaliados todos os ecocardiogramas realizados no período de 2006 a 2016 no serviço de ecocardiografia do Hospital de Base de São José do Rio Preto, sendo o total de 112.930 exames. Foram selecionados aqueles com diagnóstico de cardiomiopatia hipertrófica ou espessura parietal > 15 mm, e incluídos na análise 132 pacientes.Resultados: Regurgitação valvar mitral de grau moderado e importante esteve presente em 25% e 5,3% dos pacientes, respectivamente, sendo que a regurgitação mitral esteve independentemente correlacionada com a forma obstrutiva de cardiomiopatia hipertrófica.Conclusão: A regurgitação mitral é achado frequente em pacientes com cardiomiopatia hipertrófica, no entanto, a insuficiência mitral importante é extremamente incomum e está correlacionada com a forma obstrutiva da doença

Hypertrophic Cardiomyopathy (HCM) is a genetic disease that affects thousands of people around the world.Objectives:The present study aims to evaluate the presence of mitral regurgitation in patients with HCM, as well as its relationship with left ventricular Doppler echocardiographic variables. The mitral valve failure found in these patients is an extremely important finding, since it is able to predict the survival and mortality rate of the patients affected by HCM.Materials and Methods: All echocardiograms performed from 2006 to 2016 in the echocardiographic service of Hospital de Base de São José do Rio Preto were evaluated. A total of 112,930 tests were gathered, of which those with HCM diagnosis or wall thickness >15 mm were selected and 132 patients were included in the analysis.Results: Moderate and major mitral valve regurgitation is present in 25% and 5.3% of the patients, respectively, and MRI is independently correlated with the obstructive form of HCM.Conclusion: Mitral regurgitation is a frequent finding in patients with CMP, however, significant MI is extremely uncommon and is correlated with the obstructive form of the disease

GLA Gene Mutation in Hypertrophic Cardiomyopathy with a New Variant Description: Is it Fabry's Disease? / Mutação do Gene GLA na Cardiomiopatia Hipertrófica com Descrição de Nova Variante: É Doença de Fabry?

Abstract Background: Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations in the alpha galactosidase A gene (GLA) that lead to the enzymatic deficiency of alpha galactosidase (α-Gal A), resulting in the accumulation of globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3), causing multiple organ dysfunctions. Objective: To perform GLA gene screening in a group of patients with echocardiographic diagnosis of hypertrophic cardiomyopathy (HCM). Methods: a cross-sectional study was conducted with HCM patients from a university hospital. Patients with coronary artery disease and valvulopathies were excluded. Mutation analysis of the GLA gene was performed. In male subjects, the analysis was performed after evidence of low α-Gal A activity. Results: 60 patients with echocardiographic diagnosis of HCM were included. Age ranged from 12 to 85 years and 60% were women. Mean myocardial fibrosis percentage on MRI was 10.7 ± 13.1% and mean ventricular thickness was18.7 ± 6.7 mm. Four patients had the following GLA gene mutations: c.967C>A (p.Pro323Thr), not yet described in the literature; c.937G>T (p.Asp313Tyr); and c.352C>T (p.Arg118Cys). All patients had normal levels of lyso-Gb3 and non-ischemic myocardial fibrosis on magnetic resonance imaging; one patient had proteinuria and one patient had ventricular tachycardia. Conclusion: in this study, the frequency of mutation in the GLA gene in patients with HCM was 6.7%. A novel mutation in exon 6 of the GLA gene, c.967C>A (p.Pro323Thr), was identified. Patients with HCM may have GLA mutations and FD should be ruled out. Plasma (lyso-Gb3) levels do not seem to be sufficient to attain a diagnosis and organ biopsy should be considered.

Resumo Fundamento: A doença de Fabry (DF) é uma doença de armazenamento lisossômico ligada ao cromossomo X, devido a mutações no gene da alfa galactosidase A (GLA), levando a deficiência enzimática de alfa-galactosidase (α-Gal A) e acúmulo de globotriaosilceramida (Gb3) e globotriaosilsulfingosina (liso-Gb3), causando disfunção de múltiplos órgãos. Objetivo: realizar a triagem do gene GLA em um grupo de pacientes com diagnóstico ecocardiográfico de cardiomiopatia hipertrófica (CMH). Métodos: estudo transversal realizado com pacientes com CMH em um hospital universitário. Pacientes com doença arterial coronariana e valvopatias foram excluídos. Foi realizada análise de mutação do gene GLA. Em indivíduos do sexo masculino, a análise foi realizada após evidência de baixa atividade de α-Gal A. Resultados: Foram incluídos 60 pacientes com diagnostico ecocardiográfico de CMH. A idade variou de 12 a 85 anos e 60% eram mulheres. O percentual médio de fibrose miocárdica na RM foi 10,7 ± 13,1% e a espessura ventricular média foi 18,7 ± 6,7 mm. Quatro pacientes tinham as seguintes mutações do GLA: c.967C>A (p.Pro323Thr), ainda não descrita na literatura; c.937G>T (p.Asp313Tyr); e c.352C>T (p.Arg118Cys). Todos os pacientes apresentavam níveis normais de liso-Gb3 e fibrose miocárdica não isquêmica na ressonância magnética; um paciente apresentou proteinúria; um paciente apresentou taquicardia ventricular. Conclusão: Neste estudo, a frequência de mutação no gene GLA em pacientes com CMH foi 6,7%. Uma nova mutação no exon 6 do gene GLA, c.967C>A (p.Pro323Thr), foi identificada. Pacientes com CMH podem ter mutações do GLA e a DF deve ser excluída. Os níveis plasmáticos de (liso-Gb3) não parecem ser suficientes para fazer um diagnóstico e biópsia de órgãos deve ser considerada.

Myosin-binding Protein C Compound Heterozygous Variant Effect on the Phenotypic Expression of Hypertrophic Cardiomyopathy / Mutação em Hetrozigose Composta no Gene da Proteína C Ligante de Miosina e sua Expressão Fenotípica na Cardiomiopatia Hipertrófica

Abstract Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic disease caused by mutations in genes encoding sarcomere proteins. It is the major cause of sudden cardiac death in young high-level athletes. Studies have demonstrated a poorer prognosis when associated with specific mutations. The association between HCM genotype and phenotype has been the subject of several studies since the discovery of the genetic nature of the disease. This study shows the effect of a MYBPC3 compound variant on the phenotypic HCM expression. A family in which a young man had a clinical diagnosis of HCM underwent clinical and genetic investigations. The coding regions of the MYH7, MYBPC3 and TNNT2 genes were sequenced and analyzed. The proband present a malignant manifestation of the disease, and is the only one to express HCM in his family. The genetic analysis through direct sequencing of the three main genes related to this disease identified a compound heterozygous variant (p.E542Q and p.D610H) in MYBPC3. A family analysis indicated that the p.E542Q and p.D610H alleles have paternal and maternal origin, respectively. No family member carrier of one of the variant alleles manifested clinical signs of HCM. We suggest that the MYBPC3-biallelic heterozygous expression of p.E542Q and p.D610H may cause the severe disease phenotype seen in the proband.

Resumo A cardiomiopatia hipertrófica (CMH) é uma doença autossômica dominante causada por mutações em genes que codificam as proteínas dos sarcômeros. É a principal causa de morte súbita cardíaca em atletas jovens de alto nível. Estudos têm demonstrado um pior prognóstico associado a mutações específicas. A associação entre genótipo e fenótipo em CMH tem sido objeto de diversos estudos desde a descoberta da origem genética dessa doença. Este trabalho apresenta o efeito de uma mutação composta em MYBPC3 na expressão fenotípica da CMH. Uma família na qual um jovem tem o diagnóstico clínico de CMH foi submetida à investigação clínica e genética. As regiões codificadoras dos genes MYH7, MYBPC3 e TNNT2 foram sequenciadas e analisadas. O probando apresenta uma manifestação maligna da doença e é o único em sua família a desenvolver CMH. A análise genética pelo sequenciamento direto dos três principais genes relacionados à essa doença identificou uma variante em heterozigose composta (p.E542Q e p.D610H) em MYBPC3. A análise da família mostrou que os alelos p.E542Q e p.D610H tem origem paterna e materna, respectivamente. Nenhum familiar portador de um dos alelos variantes manifestou sinais clínicos de CMH. Sugerimos que a expressão heterozigótica bialélica de p.E542Q e p.D610H pode ser responsável pelo fenótipo severo da doença encontrada no probando.

Identificación y expresión diferencial del factor de transcripción asociado a microftalmia en corazón y cardiomiocitos aislados de cobayo: su posible papel en la hipertrofia y la viabilidad / Identification and differential expression of the microphthalmia-associated transcription factor in heart and isolated cardiomyocytes from Guinea pigs: Possible role in hypertrophy and viability

Introducción. El factor de transcripción asociado a la microftalmia ( Microphtalmia-Associated Transcription Factor , MITF) regula la expresión de genes específicos, pero no se conoce su expresión y su función a nivel cardiaco. Objetivos. Identificar la expresión del MITF en corazón y en cardiomiocitos aislados de cobayo, describir los cambios morfológicos asociados con su disminución y evaluar los niveles relativos de su expresión en cardiomiocitos aislados en condiciones de preacondicionamiento isquémico. Materiales y métodos. El análisis de la expresión relativa de la isoforma específica de tejido cardiaco ( heart-type MITF, MITF-H), se determinó mediante reacción en cadena de la polimerasa (PCR) en tiempo real semicuantitativa, secuenciación y Western blot . La disminución del ARNm del MITF se indujo con un ARN pequeño de interferencia ( short hairpin RNA interference , shRNAi) específico. El tamaño, el diámetro y el número de fibras musculares se evaluaron por observación directa con microscopía de luz. Resultados. Se amplificó un fragmento de 281 pb de ADNc; el análisis de la secuencia confirmó la identidad del exón 1 y la isoforma H del MITF. La interferencia del ARNm del MITF se asoció con un mayor índice cardiaco (peso corazón/peso corporal: 5,46 x 10 -3 Vs. 4,6 x 10 -3 ) y un incremento del diámetro de las fibras cardiacas (50,2±16 µm Vs. 38,7±14,7 µm; p<0,05, n=150). En los cardiomiocitos aislados en condiciones de preacondicionamiento isquémico, se observó una expresión relativa del MITF-H mayor que en los miocitos en normoxia y expuestos a lesión por isquemia simulada (80 y 100 veces más, n=5, p<0,05, n=3). Conclusión. Los resultados sugieren que el MITF-H podría estar involucrado en la hipertrofia, la respuesta al estrés por isquemia y la supervivencia de cardiomiocitos de cobayo.

Introduction: The microphthalmia -associated transcription factor ( MITF ) regulates the expression of specific genes and its cardiac expression and function is not known. Objectives: To identify the expression of MITF in hearts and isolated cardiomyocytes from Guinea pigs, to describe morphological changes associated with mRNA interference of MITF and to evaluate their relative changes in expression in isolated cardiomyocytes under ischemic preconditioning. Materials and methods: The cardiac specific isoform, MITF-H, and relative expression level analysis, was determined by semi-quantitative real time PCR, sequencing and Western blotting. Reduction of mRNA-MITF-H was induced by transduction of specific-MITF-shRNAi interference. The cardiac morphological changes, diameter and number of cardiac fibers were evaluated by direct observation and light microscopy. Results: A cDNA fragment of 281 bp was amplified from heart and isolated ventricular cardiac myocytes. Sequence analysis confirmed the identity of the isoform MITF-H, exon 1. The MITF silencing was associated with an increase in cardiac index (heart weight/body weight vs . 5.46 x 10 -3 vs 4.6 x 10 -3 ) and higher diameter of cardiac fibers (50.2±16 µ m vs 38,7±14,7 µ m p<0.05, n=150). In isolated cardiac myocytes under ischemic preconditioning we observed a higher relative expression compared with that measured in myocytes exposed to normoxia and simulated ischemia (eighty and one hundred times, p <0.05, n = 5). Conclusion. The results suggest that MITF-H isoform may be involved in Guinea pig cardiac hypertrophy, response to stress by ischemia and cardiomyocytes survival.

Hypertrophic cardiomyopathy: Part 1 - Introduction, pathology and pathophysiology.

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease with many genotype and phenotype variations. Earlier terminologies, hypertrophic obstructive cardiomyopathy and idiopathic hypertrophic sub‑aortic stenosis are no longer used to describe this entity. Patients present with or without left ventricular outflow tract (LVOT) obstruction. Resting or provocative LVOT obstruction occurs in 70% of patients and is the most common cause of heart failure. The pathology and pathophysiology of HCM includes hypertrophy of the left ventricle with or without right ventricular hypertrophy, systolic anterior motion of mitral valve, dynamic and mechanical LVOT obstruction, mitral regurgitation, diastolic dysfunction, myocardial ischemia, and fibrosis. Thorough understanding of pathology and pathophysiology is important for anesthetic and surgical management.

Cardiomiopatia Hipertrófica: Como as Mutações Levam à Doença? / Hypertrophic Cardiomyopathy: How do Mutations Lead to Disease?

A cardiomiopatia hipertrófica (CMH) é a doença cardíaca genética monogênica mais comum, com uma prevalência estimada de 1:500 na população em geral. Clinicamente, CMH é caracterizada por hipertrofia das paredes do ventrículo esquerdo, principalmente o septo, geralmente assimétrica, na ausência de qualquer doença cardíaca ou sistêmica que leve a uma hipertrofia secundária. A manifestação clínica da doença tem grande heterogeneidade, variando desde sintomas leves até insuficiência cardíaca, em idade avançada, e morte cardíaca súbita, em jovens, sendo causada por uma mutação em um dos genes que codificam uma proteína do sarcômero, disco Z ou controladores intracelulares de cálcio. Apesar de muitos genes e mutações já serem conhecidos por causar CMH, as vias moleculares que levam ao fenótipo ainda não são claras. Esse artigo teve como foco os mecanismos moleculares da CMH, as vias da mutação ao fenótipo clínico e como o genótipo da doença se correlaciona com o fenótipo.

Hypertrophic cardiomyopathy (HCM) is the most common monogenic genetic cardiac disease, with an estimated prevalence of 1:500 in the general population. Clinically, HCM is characterized by hypertrophy of the left ventricle (LV) walls, especially the septum, usually asymmetric, in the absence of any cardiac or systemic disease that leads to a secondary hypertrophy. The clinical course of the disease has a large inter- and intrafamilial heterogeneity, ranging from mild symptoms of heart failure late in life to the onset of sudden cardiac death at a young age and is caused by a mutation in one of the genes that encode a protein from the sarcomere, Z-disc or intracellular calcium modulators. Although many genes and mutations are already known to cause HCM, the molecular pathways that lead to the phenotype are still unclear. This review focus on the molecular mechanisms of HCM, the pathways from mutation to clinical phenotype and how the disease's genotype correlates with phenotype.

Genetic variations of b-MYH7 in Venezuelan patients with hypertrophic cardiomyopathy / Variaciones genéticas en el gen MYH7 en pacientes venezolanos con miocardiopatía hipertrófica

Hypertrophic cardiomyopathy (HCM) is a cardiac disease, characterized by marked hypertrophy and genetic variability. HCM has been associated with sarcomere protein mutations, being cardiac b-myosin (coded by the MYH7 gene) and myosin binding protein C (coded by the MYBPC3 gene) the most frequently affected proteins. As in Venezuela only the clinical analysis are performed in HCM patients, we decided to search for genetic variations in the MYH7 gene. Coding regions, including the junction exon-intron of the MYH7 gene, were studied in 58 HCM patients, whose samples were collected at the ASCARDIO Hospital (Barquisimeto, Lara state, Venezuela) and 106 control subjects from the ASCARDIO Hospital and the IVIC (Barquisimeto Lara state and Miranda, Venezuela, respectively). The blood samples were analyzed by genomic DNA isolation, followed by polymerase chain reaction and sequence analysis. The screening of the MYH7 gene revealed eight already reported polymorphic variants, as well as two intronic variations in these HCM patients. Neither any missense mutations nor other pathological mutations in the MYH7 gene were found in the HCM patients.

La miocardiopatía hipertrófica (MH) es una enfermedad cardiaca primaria, caracterizada por una marcada hipertrofia y variabilidad genética. MH ha sido asociada con mutaciones en las proteínas del sarcómero, siendo la beta miosina cardiaca, codificada por el gen MYH7 y la proteína de unión a miosina C, codificada por el gen MYBPC3, las principalmente afectadas. En Venezuela únicamente se realiza el diagnóstico clínico de MH, por lo cual el objetivo principal de este trabajo fue realizar el análisis genético en los pacientes, iniciando con el gen MYH7. Para ello, se estudió la región codificante, incluyendo la región de unión exón-intron del gen MYH7 en 58 pacientes provenientes de ASCARDIO (Barquisimeto, estado Lara) y 106 controles provenientes de ASCARDIO e IVIC (estados Lara y Miranda, Venezuela). Se colectaron las muestras de sangre para el aislamiento del ADN genómico, se realizó la técnica de PCR, seguido del análisis de secuencias para la detección de mutaciones en pacientes y controles. Se encontraron 8 polimorfismos previamente reportados, y 2 variaciones intrónicas. No se encontraron mutaciones que involucraran un cambio de aminoácido en ninguno de los exones del gen MYH7 de la beta miosina cardiaca.

Síndrome de Sengers: comunicación de dos casos en Chile / Sengers syndrome: report of two cases in chile

El Síndrome de Sengers es una enfermedad mitocondrial autosómica recesiva, producida por mutación del gen de la Acil-Glicerol Kinasa (AGK), recientemente descubierto. Se caracteriza por cataratas congénitas bilaterales, miocardiopatía hipertrófica y acidosis láctica. Puede tener miopatía esquelética leve, intolerancia al ejercicio y desarrollo mental normal. Los pacientes fallecen tempranamente debido a falla cardíaca. Dada la alta letalidad, lo infrecuente de este síndrome y la presencia de un diagnóstico confirmado, se presenta el caso clínico de 2 hermanos chilenos, fallecidos por la enfermedad, que se presentaron con el cuadro característico de cataratas congénitas bilaterales, miocardiopa-tía hipertrófica y acidosis láctica. El mayor, se operó las cataratas a los 4 meses de edad y falleció a la edad de 13 meses debido a falla cardíaca severa refractaria y falla orgánica múltiple, descompensado por una infección respiratoria. El menor se diagnosticó a los 3 meses de edad y se le confirmó la mutación del gen de AGK en Alemania. Se decidió no operarlo de las cataratas dado el mal pronóstico vital. Presentó progresión de la miocardiopatía hipertrófica y falleció súbitamente a los 8 meses de edad.

Senger's Syndrome is a recessive autosomal mitochondrial disease due to a recently discovered mutation of the Acyl-Glycerol Kinase (AGK) gen,. It is characterized by congenital bilateral cataracts, progressive hypertrophic cardiomyopathy and lactic acidosis. It may present skeletal myopathy, exercise intolerance and usually normal mental development. Patients die early in life due to heart failure. The clinical cases of two brothers with a confirmed diagnosis of Senger's syndrome are reported. The older brother was operated on for cataracts at the age of 4 months and he died when he was 13 months old due to severe refractory heart failure and multi-organ failure, decompensated by a respiratory infection. The younger brother was diagnosed at 3 month of age and the AGK gene mutation was confirmed in Germany. Cataracts were not operated on due to the the patient's extremely poor prognosis. He had progressive hypertrophic cardiomyopathy and died suddenly at 8 month of age.

Uso de la genética en el diagnóstico de la miocardiopatía hipertróficafamiliar / Use of genetics in the diagnosis of familial hypertrophic cardiomyopathy

La miocardiopatía hipertrófica familiar es una enfermedad cardíaca primaria, autosómica dominante, caracterizada por la hipertrofia del ventrículo izquierdo en ausencia de cualquier otra enfermedad del corazón, como hipertensión o estímulo metabólico. La enfermedad afecta a personas de todas las edades, siendo la consecuencia más grave la muerte súbita. La miocardiopatía hipertrófica familiar es genéticamente heterogénea y se debe mayormente a mutaciones en las proteínas del sarcómero. En Estados Unidos, afecta a uno de cada 500 individuos y es probablemente la enfermedad cardiovascular hereditaria más común. El cuadro clínico asociado puede ser muy variable, ya que abarca desde personas que manifiestan una variedad de síntomas como síncope, disnea, angina y palpitaciones, hasta la ausencia de ellos. Hasta el presente, se han identificado más de 450 mutaciones en 20 genes que codifican distintas isoformas de las proteínas del sarcómero, donde los genes mybpc-3 y myh7 son los que mayormente exhíben mutaciones. Desde hace mucho tiempo, existen diversos laboratorios en el mundo que desean establecer un test genético como rutina, sin embargo, ha resultado seruna labor difícil por la complejidad de la enfermedad, y la heterogeneidad genética asociada.

Familial hypertrophic cardiomyopathy is a primary myocardial autosomal dominant disease, characterized by increased left ventricular mass and wall thickness in the absence of a pressure overload or metabolic stimulus. This disease affect to people of all ages, being the sudden death its principal consequence. FHC is genetically heterogeneous and can be caused by mutations in one of several sarcomeric genes. In the United States, affect nearly 1 in 500 people, being the most common genetic heart disease. Clinical expression of the disease vary markedly, and may include syncope, dyspnea, angina, and palpitation, but symptoms may also be absent, or be nonspecific. Until now it have identified more of 450 mutations in 20 genes of sarcomeric protein, being mybpc3 and myh7 genes are exhibited mainly mutations. The wish of the different lab at the worldis establish one genetic test for the diagnostic of the disease but is very difficult due to complexity of the disease and the genetic heterogeneity associated.

Genetic variations of β-MYH7 in hypertrophic cardiomyopathy and dilated cardiomyopathy.

CONTEXT: Hypertrophic cardiomyopathy (HCM) is known to be manifested by mutations in 12 sarcomeric genes and dilated cardiomyopathy (DCM) is known to manifest due to cytoskeletal mutations. Studies have revealed that sarcomeric mutations can also lead to DCM. Therefore, in the present study, we have made an attempt to compare and analyze the genetic variations of beta-myosin heavy chain gene (β-MYH7), which are interestingly found to be common in both HCM and DCM. The underlying pathophysiological mechanism leading to two different phenotypes has been discussed in this study. Till date, about 186 and 73 different mutations have been reported in HCM and DCM, respectively, with respect to this gene. AIM: The screening of β-MYH7 gene in both HCM and DCM has revealed some common genetic variations. The aim of the present study is to understand the pathophysiological mechanism underlying the manifestation of two different phenotypes. MATERIALS AND METHODS: 100 controls, 95 HCM and 97 DCM samples were collected. Genomic DNA was extracted following rapid nonenzymatic method as described by Lahiri and Nurnberger (1991), and the extracted DNA was later subjected to polymerase chain reaction (PCR) based single stranded conformation polymorphism (SSCP) analysis to identify single nucleotide polymorphism (SNP)s/mutations associated with the diseased phenotypes. RESULTS AND CONCLUSION: Similar variations were observed in β-MYH7 exons 7, 12, 19 and 20 in both HCM and DCM. This could be attributed to impaired energy compromise, or to dose effect of the mutant protein, or to even environmental factors/modifier gene effects wherein an HCM could progress to a DCM phenotype affecting both right and left ventricles, leading to heart failure.

Estudo de mutações causadoras de cardiomiopatia hipertrófica em um grupo de pacientes no Espírito Santo, Brasil / Study of mutations causing hypertrophic cardiomyopathy in a group of patients from Espirito Santo, Brazil / Estudio de mutaciones causadoras de cardiomiopatía hipertrófica en un grupo de pacientes en Espírito Santo, Brasil

Fundamento: A cardiomiopatia hipertrófica (CH) é a doença cardíaca hereditária mais frequente, causada por mutações nos genes codificadores para proteínas do sarcômero. Embora mais de 430 mutações tenham sido identificadas em vários continentes e países, não há relato de que isso tenha sido estudado no Brasil. Objetivo: Conduzir um estudo genético para identificar mutações genéticas que causam a CH em um grupo de pacientes no estado do Espírito Santo, Brasil. Métodos: Usando a técnica SSCP, 12 exons dos três principais genes envolvidos com a CH foram estudados: exons 15, 20, 21, 22 e 23 do gene da cadeia pesada da β-miosina (MYH7), exons 7, 16, 18, 22 e 24 do gene da proteína C ligada à miosina (MYBPC3) e exons 8 e 9 do gene da troponina T (TNNT2). Resultados: 16 alterações foram encontradas, incluindo duas mutações, uma delas possivelmente patogênica no gene MYBPC3 gene (p. Glu441Lys) e a outra patogênica já descrita no gene TNNT2 (p.Arg92Trp); 8 variações de seqüência raras e 6 variações de seqüência com frequência alélica maior do que 1 por cento (polimorfismos). Conclusão: Com esses dados, é possível concluir que a genotipagem dos pacientes é factível em nosso meio. É possível que a variante p.Glu441Lys no exon 16 do gene MYBPC3 seja patogênica, resultando em um fenótipo mais leve do que o encontrado em associação com outras mutações. A variante p.Arg92Trp no exon 9 do gene TNNT2 não resulta em um fenótipo tão homogêneo como descrito anteriormente e pode levar à hipertrofia grave.

Background: Hypertrophic cardiomyopathy (HC) is the most frequent cardiac hereditary disease, caused by mutations in sarcomere protein coding genes. Although more than 430 mutations have been identified in several continents and countries, there have been no reports of mutations in Brazil. Objective: To carry out a genetic study to identify genetic mutations that cause HC in a group of patients in Espirito Santo, Brazil. Methods: Using the SSCP technique, 12 exons from the three main genes involved in HC were studied: exons 15, 20, 21, 22 and 23 of the β-myosin heavy chain gene (MYH7), exons 7, 16, 18, 22 and 24 of the myosin binding protein C gene (MYBPC3) and exons 8 and 9 of troponin T gene (TNNT2). Results: 16 alterations were found, including two mutations, one of them possibly pathogenic in the MYBPC3 gene (p. Glu441Lys) and another pathogenic one, previously described in the TNNT2 gene (p.Arg92Trp), 8 rare sequence variations and 6 sequence variations with allelic frequency higher than 1 percent (polymorphisms). Conclusion: These data allow the conclusion that the genotyping of patients is feasible in our country. It is possible that the isolated p.Glu441Lys variant identified in exon 16 of the MYBPC3 gene is pathogenic, promoting a milder phenotype than that found when in association with other mutations. The p.Arg92Trp variant in the exon 9 of TNNT2 gene does not promote such a homogeneous phenotype as previously described and it can lead to severe hypertrophy.

Fundamento: La cardiomiopatía hipertrófica (CH) es la enfermedad cardíaca hereditaria más frecuente, causada por mutaciones en los genes codificadores para proteínas del sarcómero. Aunque se hayan identificado más de 430 mutaciones en varios continentes y países, no hay relato de que esto se haya estudiado en Brasil. Objetivo: Conducir un estudio genético para identificar mutaciones genéticas que causan la CH en un grupo de pacientes en el estado de Espírito Santo, Brasil. Métodos: Usando la técnica SSCP, se estudiaron 12 exones de los tres principales genes involucrados con la CH: exones 15, 20, 21, 22 y 23 del gen de la cadena pesada de la β-miosina (MYH7), exones 7, 16, 18, 22 y 24 del gen de la proteína C unida a la miosina (MYBPC3) y exones 8 y 9 del gen de la troponina T (TNNT2). Resultados: Se encontraron 16 alteraciones, incluyendo dos mutaciones, una de ellas posiblemente patogénica en el gen MYBPC3 gen (p. Glu441Lys) y otra patogénica ya descrita en el gen TNNT2 (p. Arg92Trp); 8 variaciones de secuencia raras y 6 variaciones de secuencia con frecuencia alélica mayor que el 1 por ciento (polimorfismos). Conclusiones: Con estos datos, es posible concluir que el genotipaje de los pacientes es factible en nuestro medio. Es posible que la variante p.Glu441Lys en el exón 16 del gen MYBPC3 sea patogénica, resultando en un fenotipo más leve que el encontrado en asociación con otras mutaciones. La variante p.Arg92Trp en el exón 9 del gen TNNT2 no resulta en un fenotipo tan homogéneo como el descrito anteriormente y puede llevar a hipertrofia grave.