Cardiomiopatia Hipertrófica: uma revisão pelo olhar da ressonância magnética / Hypertrophic Cardiomyopathy: a review using magnetic resonance imaging

A cardiomiopatia hipertrófica é a cardiopatia genética mais frequente na população geral e é caracterizada por uma hipertrofia ventricular esquerda assimétrica. Entretanto, as alterações fenotípicas desta cardiomiopatia vão muito além da hipertrofia ventricular, e incluem alterações do aparato valvar mitral, dos músculos papilares e do ventrículo direito. Devido à dificuldade no diagnóstico diferencial entre as múltiplas causas de hipertrofia, a ressonância magnética cardíaca vem cumprindo um papel fundamental na avaliação diagnóstica e prognóstica desta cardiomiopatia. A cineressonância magnética na definição da localização e extensão da hipertrofia, o realce tardio, na detecção das áreas de fibrose miocárdica e técnicas mais recentes como o Mapa de T1 que avalia a fibrose intersticial e o volume extracelular; e finalmente o Tissue Tracking na análise da deformação miocárdica.(AU)

Hypertrophic cardiomyopathy, the most common genetic cardiopathy in the general population, is characterized by asymmetric left ventricular hypertrophy. However, the phenotypic changes in this cardiomyopathy extend beyond ventricular hypertrophy and include changes in the mitral valve apparatus, papillary muscles, and right ventricle. Due to the difficult differential diagnosis among multiple causes of hypertrophy, cardiac magnetic resonance has played a fundamental role in its diagnostic and prognostic evaluation; magnetic cine-resonance in defining the location and extent of hypertrophy; late enhancement, in the detection of areas of myocardial fibrosis; more recent techniques such as T1 mapping that assesses interstitial fibrosis and extracellular volume; and finally tissue tracking in the analysis of myocardial deformation. (AU)

Novel frameshift variant in MYL2 reveals molecular differences between dominant and recessive forms of hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is characterized by thickening of the ventricular muscle without dilation and is often associated with dominant pathogenic variants in cardiac sarcomeric protein genes. Here, we report a family with two infants diagnosed with infantile-onset HCM and mitral valve dysplasia that led to death before one year of age. Using exome sequencing, we discovered that one of the affected children had a homozygous frameshift variant in Myosin light chain 2 (MYL2:NM_000432.3:c.431_432delCT: p.Pro144Argfs*57;MYL2-fs), which alters the last 20 amino acids of the protein and is predicted to impact the most C-terminal of the three EF-hand domains in MYL2. The parents are unaffected heterozygous carriers of the variant and the variant is absent in control cohorts from gnomAD. The absence of the phenotype in carriers and the infantile presentation of severe HCM is in contrast to HCM associated with dominant MYL2 variants. Immunohistochemical analysis of the ventricular muscle of the deceased patient with the MYL2-fs variant showed a marked reduction of MYL2 expression compared to an unaffected control. In vitro overexpression studies further indicate that the MYL2-fs variant is actively degraded. In contrast, an HCM-associated missense variant (MYL2:p.Gly162Arg) and three other MYL2 stop-gain variants (p.E22*, p.K62*, p.E97*) that result in loss of the EF domains are stably expressed but show impaired localization. The degradation of the MYL2-fs can be rescued by inhibiting the cell's proteasome function supporting a post-translational effect of the variant. In vivo rescue experiments with a Drosophila MYL2-homolog (Mlc2) knockdown model indicate that neither the MYL2-fs nor the MYL2:p.Gly162Arg variant supports normal cardiac function. The tools that we have generated provide a rapid screening platform for functional assessment of variants of unknown significance in MYL2. Our study supports an autosomal recessive model of inheritance for MYL2 loss-of-function variants in infantile HCM and highlights the variant-specific molecular differences found in MYL2-associated cardiomyopathy.

New non-renal congenital disorders associated with medullary sponge kidney (MSK) support the pathogenic role of GDNF and point to the diagnosis of MSK in recurrent stone formers.

Medullary sponge kidney (MSK) is a congenital renal disorder. Its association with several developmental abnormalities in other organs hints at the likelihood of some shared step(s) in the embryogenesis of the kidney and other organs. It has been suggested that the REarranged during Transfection (RET) proto-oncogene and the Glial cell line-Derived Neurotrophic Factor (GDNF) gene are defective in patients with MSK, and both RET and GDNF are known to have a role in the development of the central nervous system, heart, and craniofacial skeleton. Among a cohort of 143 MSK patients being followed up for nephrolithiasis and chronic kidney disease at our institution, we found six with one or more associated non-renal anomalies: one patient probably has congenital hemihyperplasia and hypertrophic cardiomyopathy with adipose metaplasia and mitral valve prolapse; one has Marfan syndrome; and the other four have novel associations between MSK and nerve and skeleton abnormalities described here for the first time. The discovery of disorders involving the central nervous system, cardiovascular system and craniofacial skeleton in MSK patients supports the hypothesis of a genetic alteration on the RET-GDNF axis having a pivotal role in the pathogenesis of MSK, in a subset of patients at least. MSK seems more and more to be a systemic disease, and the identification of extrarenal developmental defects could be important in arousing the suspicion of MSK in recurrent stone formers.

Persistent Pulmonary Hypertension in a Neonate With Transposition of Great Arteries and Intact Ventricular Septum: A Case Report and Review of the Literature.

Transposition of the great arteries (TGA) with intact ventricular septum (IVS) has very favorable short- and long-term surgical outcome. Although rare, when associated with persistent pulmonary hypertension (PPH), it exhibits significant mortality risk and management challenges. We report the case of a neonate with TGA with IVS and PPH who underwent successful early surgical repair with emphasis on clinical management and review of the literature.

Fatal congenital hypertrophic cardiomyopathy and a pancreatic nodule morphologically identical to focal lesion of congenital hyperinsulinism in an infant with costello syndrome: case report and review of the literature.

Costello syndrome is characterized by constitutional mutations in the proto-oncogene HRAS, causing dysmorphic features, multiple cardiac problems, intellectual disability, and an increased risk of neoplasia. We report a male infant with dysmorphic features, born prematurely at 32 weeks, who, during his 3-month life span, had an unusually severe and ultimately fatal manifestation of hypertrophic cardiomyopathy and hyperinsulinemic hypoglycemia. Molecular studies in this patient demonstrated the uncommon Q22K mutation in the HRAS gene, diagnostic of Costello syndrome. The major autopsy findings revealed hypertrophic cardiomyopathy, congenital myopathy, and a 1.4-cm pancreatic nodule that was positive for insulin expression and morphologically identical to a focal lesion of congenital hyperinsulinism. Sequencing of KCNJ11 and ABCC8, the 2 most commonly mutated genes in focal lesion of congenital hyperinsulinism, revealed no mutations. While hyperinsulinism is a recognized feature of RASopathies, a focal proliferation of endocrine cells similar to a focal lesion of hyperinsulinism is a novel pathologic finding in Costello syndrome.

Whole-exome sequencing identifies a mutation in the mitochondrial ribosome protein MRPL44 to underlie mitochondrial infantile cardiomyopathy.

BACKGROUND: The genetic complexity of infantile cardiomyopathies is remarkable, and the importance of mitochondrial translation defects as a causative factor is only starting to be recognised. We investigated the genetic basis for infantile onset recessive hypertrophic cardiomyopathy in two siblings. METHODS AND RESULTS: Analysis of respiratory chain enzymes revealed a combined deficiency of complexes I and IV in the heart and skeletal muscle. Exome sequencing uncovered a homozygous mutation (L156R) in MRPL44 of both siblings. MRPL44 encodes a protein in the large subunit of the mitochondrial ribosome and is suggested to locate in close proximity to the tunnel exit of the yeast mitochondrial ribosome. We found severely reduced MRPL44 levels in the patient's heart, skeletal muscle and fibroblasts suggesting that the missense mutation affected the protein stability. In patient fibroblasts, decreased MRPL44 affected assembly of the large ribosomal subunit and stability of 16S rRNA leading to complex IV deficiency. Despite this assembly defect, de novo mitochondrial translation was only mildly affected in fibroblasts suggesting that MRPL44 may have a function in the assembly/stability of nascent mitochondrial polypeptides exiting the ribosome. Retroviral expression of wild-type MRPL44 in patient fibroblasts rescued the large ribosome assembly defect and COX deficiency. CONCLUSIONS: These findings indicate that mitochondrial ribosomal subunit defects can generate tissue-specific manifestations, such as cardiomyopathy.

Pulmonary interstitial glycogenosis associated with pulmonary hypertension and hypertrophic cardiomyopathy.

A neonate with pulmonary interstitial glycogenosis, pulmonary hypertension, and hypertrophic cardiomyopathy is described. The fatal outcome for this patient contrasts with the reported favorable prognosis associated with isolated pulmonary interstitial glycogenosis. To the authors' knowledge, the association of pulmonary interstitial glycogenosis and hypertrophic cardiomyopathy has not been reported previously. The authors have broadened the phenotype of pulmonary interstitial glycogenosis and demonstrate the diagnostic value of lung biopsy in cases of unexplained neonatal pulmonary hypertension.

A rasopathy phenotype with severe congenital hypertrophic obstructive cardiomyopathy associated with a PTPN11 mutation and a novel variant in SOS1.

The RAS-MAPK pathway is critical for human growth and development. Abnormalities at different steps of this signaling cascade result in neuro-cardio-facial-cutaneous syndromes, or the RASopathies, a group of disorders with overlapping yet distinct phenotypes. RASopathy patients have variable degrees of intellectual disability, poor growth, relative macrocephaly, ectodermal abnormalities, dysmorphic features, and increased risk for certain malignancies. Congenital heart disease, particularly hypertrophic cardiomyopathy (HCM) and pulmonic stenosis, are prominent features in these disorders. Significant locus heterogeneity exists for many of the RASopathies. Traditionally, these diseases were thought to be inherited in an autosomal dominant manner. However, recently patients with defects in two components of this pathway and overlapping features of various forms of Noonan syndrome and neurofibromatosis 1 and have been reported. Here we present a patient with severe, progressive neonatal HCM, elevated urinary catecholamine metabolites, and dysmorphic features in whom we identified a known LEOPARD syndrome-associated PTPN11 mutation (c.1403 C > T; p.T468M) and a novel, potentially pathogenic missense SOS1 variant (c.1018 C > T; p.P340S) replacing a rigid nonpolar imino acid with a polar amino acid at a highly conserved position. We describe detailed clinical manifestations, cardiac histopathology, and the molecular genetic findings. Oligogenic models of inheritance with potential synergistic effects should be considered in the RASopathies.

Cardiomiopatia hipertrófica / Hypertrophic cardiomyopathy

A cardiomiopatia hipertrófica é uma doença genética autossômica dominante relativamente comum (prevalência =0,2 por cento), caracterizada por hipertrofia ventricular na ausência de outras doenças que possam levar a essa alteração. Pode ser manifestar desde a forma assintomática até as apresentações graves e refratárias ao tratamento clínico. Recentemente a literatura vem consolidando métodos mais acurados para o diagnóstico (ressonância magnética), demonstrando os resultados seguros de formas invasivas de tratamento (como a alcoolização septal) para casos graves, e discutindo novos fatores de risco para morte súbita. Nesta revisão serão abordados esses avanços, além de se revisarem os aspectos clássicos da doença, buscando trazer informações que sejam relevantes para a sua abordagem prática.

Phenotypic consequences of a novel SCO2 gene mutation.

SCO2 is a cytochrome c oxidase (COX) assembly gene. Mutations in the SCO2 gene have been associated with fatal infantile cardioencephalomyopathy. We report on the phenotype of a novel SCO2 mutation in two siblings with fatal infantile cardioencephalomyopathy. The index patient died of heart failure at 25 days of age. Muscle biopsy was performed for histology and biochemical study of the oxidative phosphorylation system complexes. The entire coding region of the SCO2 gene was sequenced. Autopsy was performed on the index patient and on a female sibling delivered at 23 weeks of gestation following termination of pregnancy during which amniocentesis and genetic testing had been performed. Muscle biopsy and biochemical analysis of heart and skeletal muscle detected a severe isolated COX-IV deficiency. Pathologic findings in both patients confirmed hypertrophic cardiomyopathy. Sequencing of the SCO2 gene showed compound heterozygous mutation; the common E140K mutation and a novel W36X nonsense mutation. Newborns with a combination of hypotonia and cardiomyopathy should be evaluated for multiple congenital anomaly syndromes, inborn errors of metabolism and mitochondrial derangements, and may require extensive diagnostic testing. Mutations in the SCO2 gene are a cause of prenatal-onset hypertrophic cardiomyopathy.

Diagnosis and natural history of isolated congenital pulmonary regurgitation in fetal life.

We describe a rare instance of isolated pulmonary regurgitation caused by a dysplastic pulmonary valve which was detected prenatally. Fetal echocardiography demonstrated severe pulmonary regurgitation, and progressive cardiomegaly because of right ventricular volume overload. After birth, conservative therapy was successful in alleviating the pulmonary vascular resistance, and the pulmonary regurgitation gradually decreased.

Infantile hypertrophic cardiomyopathy of glycogenosis type IX: isolated cardiac phosphorylase kinase deficiency.

Glycogen storage disease confined to the heart due to cardiac phosphorylase kinase deficiency causes a fatal infantile cardiomyopathy. Cardiomegaly can be detected in utero and is progressive. Electrocardiographic and echocardiographic findings are characteristic but not specific; these include large QRS complexes, short PR interval, and a hypertrophic nonobstructive pattern. Conclusive diagnosis requires biochemical analysis of myocardium, which may not be possible premortem due to the amount of tissue required. Pathologic examination of a standard cardiac biopsy can provide a presumptive diagnosis. There is no current treatment except a heart transplant. Infants succumb to heart failure and/or respiratory compromise due to pulmonary compression. This is a rare entity; only three cases have been reported to our knowledge. We report two additional cases.

Multiple aneurysmal dysplasia of pulmonary valvular sinuses with congenital focal aplasia of the annulus.

We report the case of a 22-year-old woman in whom a focal aplasia of the pulmonary valve annulus associated with a multiple aneurysmal compensatory dysplasia was found. This patient had been followed since the age of seven years for a congenital asymmetric hypertrophic cardiomyopathy. Cardiac Doppler analysis showed significant pulmonary valvular insufficiency. The patient underwent heart transplant surgery because of total and refractory cardiac insufficiency. Pathological examination of the explanted heart (at the European Homograft Bank) enabled us to describe this valvular malformation. To date, this anomaly has not been described in the literature. Whether it is a malformation discovered fortuitously, or whether it is responsible in part for some of the signs associated with congenital hypertrophic cardiomyopathy is unclear. However, its role might be disclosed by a rigorous investigation of the patient's family.

Life-threatening cardiac involvement throughout life in a case of Costello syndrome.

Costello syndrome is characterized by poor postnatal growth, mental retardation, curly hair, coarse face, loose skin of the hands and feet, and nasal papillomata. Patients with Costello syndrome have a high incidence of cardiac involvement, such as arrhythmias, hypertrophic cardiomyopathy, or congenital anomalies. The importance of cardiac involvement in Costello syndrome has not been strongly emphasized thus far, although arrhythmia and hypertrophic cardiomyopathy are both serious forms of cardiac involvement. We report the case of a Japanese girl with Costello syndrome, who experienced life-threatening cardiac involvement throughout her life.