Sarcomere gene variants act as a genetic trigger underlying the development of left ventricular noncompaction.

BACKGROUND: Left ventricular noncompaction (LVNC) is a primary cardiomyopathy with heterogeneous genetic origins. The aim of this study was to elucidate the role of sarcomere gene variants in the pathogenesis and prognosis of LVNC. METHODS AND RESULTS: We screened 82 Japanese patients (0-35 years old), with a diagnosis of LVNC, for mutations in seven genes encoding sarcomere proteins, by direct DNA sequencing. We identified variants in a significant proportion of cases (27%), which were associated with poor prognosis (p = 0.012), particularly variants in TPM1, TNNC1, and ACTC1 (p = 0.012). To elucidate the pathological role, we developed and studied human-induced pluripotent stem cells (hiPSCs) from a patient carrying a TPM1 p.Arg178His mutation, who underwent heart transplantation. These cells displayed pathological changes, with mislocalization of tropomyosin 1, causing disruption of the sarcomere structure in cardiomyocytes, and impaired calcium handling. Microarray analysis indicated that the TPM1 mutation resulted in the down-regulation of the expression of numerous genes involved in heart development, and positive regulation of cellular process, especially the calcium signaling pathway. CONCLUSIONS: Sarcomere genes are implicated as genetic triggers in the development of LVNC, regulating the expression of numerous genes involved in heart development, or modifying the severity of disease.

Clinical and Echocardiographic Impact of Tafazzin Variants on Dilated Cardiomyopathy Phenotype in Left Ventricular Non-Compaction Patients in Early Infancy.

BACKGROUND: Left ventricular non-compaction (LVNC) is a cardiomyopathy morphologically characterized by 2-layered myocardium and numerous prominent trabeculations, and is often associated with dilated cardiomyopathy (DCM). Variants in the gene encoding tafazzin (TAZ) may change mitochondrial function and cause dysfunction of many organs, but they also contribute to the DCM phenotype in LVNC, and the clinical and echocardiographic features of children with this phenotype are poorly understood. Methods and Results: We enrolled 92 DCM phenotype LVNC patients and performed next-generation sequencing to identify the genetic etiology. Ten TAZ variants were identified in 15 male patients (16.3%) of the 92 patients, including 3 novel missense substitutions. The patients with TAZ variants had a higher frequency of early onset of disease (92.3% vs. 62.3%, P=0.0182), positive family history (73.3% vs. 20.8%, P=0.0001), and higher LV posterior wall thickness Z-score (8.55±2.60 vs. 5.81±2.56, P=0.0103) than those without TAZ variants, although the mortality of both groups was similar. CONCLUSIONS: This study provides new insight into the impact of DCM phenotype LVNC and emphasizes the clinical advantages available for LVNC patients with TAZ variants.

MicroRNA-145-5p and microRNA-320a encapsulated in endothelial microparticles contribute to the progression of vasculitis in acute Kawasaki Disease.

Kawasaki Disease (KD) is an acute inflammatory disease that takes the form of systemic vasculitis. Endothelial microparticles (EMPs) have been recognized as an important transcellular delivery system. We hypothesized whether EMPs are involved in vasculitis in acute KD. Fifty patients with acute KD were enrolled, divided into two subgroups: those with coronary artery lesions (CAL) (n = 5) and those without CAL (NCAL) (n = 45). EMPs were measured using flow cytometry, and microRNA (miR) expression profiling was performed by microRNA array. The percentage of EMPs in acute KD was significantly higher than in controls (P < 0.0001). EMPs in patients with CAL rapidly increased after the initial treatment, and was significantly higher than those in NCAL (P < 0.001). In patients with CAL, we identified 2 specific miRs encapsulated in EMPs, hsa-miR-145-5p and hsa-miR-320a, which are predicted to affect monocyte function using in silico analysis, and were demonstrated to upregulate inflammatory cytokine mRNAs in THP-1 monocytes. In situ hybridization confirmed that hsa-miR-145-5p was preferentially expressed in CAL. EMPs may serve as a sensitive marker for the severity of vasculitis in acute KD. Moreover, these 2 specific miRs encapsulated in EMPs might be involved in inflammatory cytokine regulation and the pathogenesis of vasculitis in acute KD.

A Wide and Specific Spectrum of Genetic Variants and Genotype-Phenotype Correlations Revealed by Next-Generation Sequencing in Patients with Left Ventricular Noncompaction.

BACKGROUND: Left ventricular noncompaction (LVNC) has since been classified as a primary genetic cardiomyopathy, but the genetic basis is not fully evaluated. The aim of the present study was to identify the genetic spectrum using next-generation sequencing and to evaluate genotype-phenotype correlations in LVNC patients. METHODS AND RESULTS: Using next-generation sequencing, we targeted and sequenced 73 genes related to cardiomyopathy in 102 unrelated LVNC patients. We identified 43 pathogenic variants in 16 genes in 39 patients (38%); 28 were novel variants. Sarcomere gene variants accounted for 63%, and variants in genes associated with channelopathies accounted for 12%. MYH7 and TAZ pathogenic variants were the most common, and rare variant collapsing analysis showed variants in these genes contributed to the risk of LVNC, although patients carrying MYH7 and TAZ pathogenic variants displayed different phenotypes. Patients with pathogenic variants had early age of onset and more severely decreased left ventricular ejection fractions. Survival analysis showed poorer prognosis in patients with pathogenic variants, especially those with multiple variants: All died before their first birthdays. Adverse events were noted in 17 patients, including 13 deaths, 3 heart transplants, and 1 implantable cardioverter-defibrillator insertion. Congestive heart failure at diagnosis and pathogenic variants were independent risk factors for these adverse events. CONCLUSIONS: Next-generation sequencing revealed a wide spectrum of genetic variations and a high incidence of pathogenic variants in LVNC patients. These pathogenic variants were independent risk factors for adverse events. Patients harboring pathogenic variants showed poor prognosis and should be followed closely.

Long-Term Prognosis of Patients With Left Ventricular Noncompaction　- Comparison Between Infantile and Juvenile Types.

BACKGROUND: The natural history of left ventricular noncompaction (LVNC) is largely unsolved, so the aim of the present study was to clarify the clinical features and long-term prognosis of children with LVNC until adulthood.Methods and Results:We conducted a nationwide survey over 20 years and compared the clinical features, anatomical characteristics and long-term prognosis of 205 patients divided into 2 classifications: infantile type (diagnosed at <1 year of age: 108 cases) and juvenile type (diagnosed 1-15 years of age: 97 cases). Most patients diagnosed during infancy had heart failure (HF) at initial presentation (60.19%), while the majority of juvenile cases were asymptomatic (53.61%) but their event-free survival rate decreased gradually, because of later HF, thromboembolism and fatal arrhythmias. The initial LVEF was significantly lower in the infantile type and correlated with the thickness of the compacted layer in the LV posterior wall (LVPWC) and LV end-diastolic dimension (LVDD) Z-score, but not to the noncompacted to compacted layer (N/C) ratio. Survival analysis showed prognosis was similarly poor for both types after 2 decades. The significant risk factors for death, heart transplantation or implantable cardioverter-defibrillator insertion were congestive HF at diagnosis and lower LVPWC Z-score but not age of onset. CONCLUSIONS: LVNC of both types showed poor long-term prognosis, therefore ongoing follow-up is recommended into adulthood. HF at diagnosis and LVPWC hypoplasia are major determinants of poor prognosis.

Postmortem genetic analysis of sudden unexplained death syndrome under 50 years of age: A next-generation sequencing study.

BACKGROUND: Recent studies on the genetic analysis of victims of sudden unexplained death syndrome (SUDS) have shown diagnostic potential. Previously, such analyses mainly targeted the major channelopathy-associated genes. OBJECTIVE: The purpose of this study was to evaluate the utility of next-generation sequencing (NGS) in the postmortem diagnosis of SUDS. METHODS: Our data are derived from 25 cases of SUDS (21 men and 4 women; age 19-50 years). A total of 70 genes were examined by NGS, and the pathogenicity of any detected rare variants with minor allele frequencies of <0.5% was evaluated using a widely used database and eight in silico algorithms. RESULTS: Five known and 15 potentially pathogenic variants with a high in silico score were identified in 14 cases. In all, 6 channelopathy-related variants were identified in 5 cases, including 2 cases with history of arrhythmia; 11 cases had cardiomyopathy- or cardiac transcription factor-related variants. Three cases with desmosomal gene- or other cardiomyopathy-related variants showed possibly related pathologic changes. Three cases with RYR2 or TBX5 variants showed possible pathogenic fibrosis of the cardiac conduction system. Only 12 variants showed moderate or strong possible pathogenicity in SUDS cases compared with qualifying controls. CONCLUSION: Hereditary heart diseases other than channelopathy may also be a significant cause of SUDS, even if clinical and pathologic findings do not show advanced disease. A combination of gene analysis using NGS and some predictive methods for detecting variants and careful pathologic evaluation may provide a reliable diagnosis of hereditary heart disease for potential SUDS cases.

A novel MYH7 gene mutation in a fetus with left ventricular noncompaction.

Left ventricular noncompaction (LVNC) is a recently defined cardiomyopathy characterized by a pattern of prominent trabecular meshwork and deep intertrabecular recesses. LVNC is rarely described in fetal life, and a small number of cases have been reported. We report the first fetal case, to our knowledge, of LVNC associated with a novel mutation in the MYH7 gene (c.1625A>C; p.Lys542Thr). This patient showed cardiomegaly on prenatal ultrasonographic examinations, with features indicating noncompaction of the myocardium apparent in the second trimester. This case highlights the importance of prenatal ultrasonography for the diagnosis of LVNC and suggests that abnormal myocardial development underlies the pathogenesis of LVNC.

Intracranial calcification in a uremic infant with Wilms' tumor in a solitary kidney.

Wilms' tumor (WT), also called nephroblastoma, is an embryonic neoplasm of the developing kidney. A previously healthy Japanese female infant had WT in a single kidney without associated congenital malformations. Preoperative chemotherapy was started for the preservation of renal tissue and function. Tumor lysis syndrome, disseminated intravascular coagulopathy, and acute renal failure were accompanying. The infant needed surgical intervention and permanent replacement therapy. At the start of emergency hemodialysis, the infant had posterior reversible leukoencephalopathy syndrome because of severe hypertension. During ongoing peritoneal dialysis, the infant suffered from anemia, dietary and fluid restriction, and restriction of time and mobility. Despite alfacalcidol and calcium supplementation, the infant had secondary hyperparathyroidism and remarkably short stature. After waiting for the completion of chemotherapy, renal transplantation from the mother was completed. Successful kidney transplantation promptly corrected preexisting metabolic abnormalities causing secondary hyperparathyroidism. Subsequently, the infant often complained of headache. Computed tomographic scanning revealed calcification in the cerebellum. Refractory secondary hyperparathyroidism was inferred as the cause. A well-functioning graft provided the infant with a greater sense of well-being and enabled her to enjoy a lifestyle free of dialysis, although the infant must continue taking transplant medications and has retained unresolved issues of short stature and ectopic intracranial calcification.