Keijiro Ibuki

Identification of a novel TPM1 mutation in a family with left ventricular noncompaction and sudden death

Left ventricular noncompaction (LVNC) is a cardiomyopathy morphologically characterized by 2-layered myocardium, numerous prominent trabeculations, and deep intertrabecular recesses communicating with the left ventricular cavity. The purpose of this study was to investigate patients with LVNC for possible disease causing mutations. We screened 4 genes (TAZ, LDB3, DTNA and TPM1) in 51 patients with LVNC for mutations by polymerase chain reaction and direct DNA sequencing. A novel missense substitution in exon 1 of TPM1 (c.109A>G: p.Lys37Glu) was identified in three affected members of a family with isolated LVNC. The substitution brings about a change in amino acid charge at a highly conserved residue and could result in aberrant mRNA splicing. This variant was not identified in 200 normal control samples. Pathologic analysis of a right ventricular myocardial specimen from the probands maternal aunt revealed endocardial and subendocardial fibrosis with prominent elastin deposition, as well as the presence of adipose tissue between muscle layers, pathologic changes that are distinct from those seen in patients with HCM or DCM. Screening of the proband and her mother for variants in other sarcomeric protein-encoding candidate genes, MYH7, MYBPC3, TNNT2, TNNI3, ACTC, MYL2, and MYL3, did not identify any other non-synonymous variants or variants in splice donor-acceptor sequences that were potentially disease causing. We conclude TPM1 is a potential candidate disease-causing gene for isolated LVNC, especially in patients experiencing sudden death.

The improvement of hypoxia correlates with neuroanatomic and developmental outcomes: Comparison of midterm outcomes in infants with transposition of the great arteries or single-ventricle physiology

OBJECTIVES We performed a prospective longitudinal study of the neuroanatomic and developmental changes in infants with transposition of the great arteries (TGA) or single-ventricle (SV) physiology to identify variables in anatomic development of the brain associated with functional impairment. METHODS Thirty-three infants with congenital heart defects, 23 with SV and 10 with TGA, were studied at around 1 year old (time 1) and 3 years old (time 2) by magnetic resonance imaging of the brain. Neurodevelomental assessment was performed at the same time. RESULTS The whole and frontal lobe volumes were significantly reduced in both groups at time 1 compared with normal control subjects (P < .01). However, by time 2 whole and frontal brain volumes were normal in the TGA group but remained significantly smaller (P < .01) in the SV group. In agreement with these findings, the mental development index (MDI) was lower (P < .05) at time 1 in both groups but improved to normal levels at time 2 in the TGA group. In the SV group, both MDI and the psychomotor development index (PDI) were significantly decreased at both time 1 and time 2 (P < .01). These patients continued to experience hypoxia, and multivariate analysis revealed that functional oxygen saturation was significantly associated with PDI. Further, the PDI score correlated with whole and regional brain volumes (P < .05). CONCLUSIONS Neuroanatomic and developmental outcomes improve progressively in infants with TGA, unlike those with SV physiology. Impaired cerebral circulation and hypoxia may have significant effects on brain growth and development in infants with critical congenital heart disease.

MicroRNA-93 may control vascular endothelial growth factor A in circulating peripheral blood mononuclear cells in acute Kawasaki disease.

Background:Kawasaki disease (KD) is the most common systemic vasculitis syndrome primarily affecting medium-sized arteries, particularly the coronary arteries. Though KD may be associated with immunological problems, the involvement of microRNAs (miRs) has not been fully described.Methods:We enrolled 23 KD patients and 12 controls. We performed miR and mRNA microarray analysis of peripheral blood mononuclear cells (PBMCs) isolated from acute KD patients and controls. Continuously, we measured specific miRs, mRNA and the expression of proteins by using reverse-transcriptase PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA).Results:We identified strikingly high levels of miR-182 and miR-296-5p during the acute febrile phase, and of miR-93, miR-145-5p, miR-145-3p, and miR-150-3p in the defervescence stage, especially in refractory KD patients. The expression of vascular endothelial growth factor A (VEGFA) mRNA, previously reported to be controlled by miR-93, was significantly elevated during the febrile phase and normalized upon treatment, negatively correlating with the expression of miR-93. Further, plasma levels of VEGF-A correlated with PBMC VEGFA mRNA expression.Conclusion:Several miRs are highly specific to the acute phase of KD, and may participate in regulating the expression of genes in pathways associated with KD. In particular, miR-93 may participate in regulating expression of VEGF-A and contribute to the pathogenesis of arteritis in acute KD.

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.

Percutaneous catheter aspiration thrombectomy for the occluded stents of pulmonary artery in children with single ventricle physiology after fontan surgery

Successful surgical palliation with the Fontan procedure allows survival into adulthood for many patients born with single ventricle (SV) physiology, but the limited studies reported incidence of perioperative and long‐term complications including thromboembolic events. Chronic pulmonary embolism is a common complication in patients with Fontan circulation, and may have serious consequences. Percutaneous intervention may be less invasive option for such a high‐risk population than surgery is. We described two patients who developed complete thrombosis of the left pulmonary artery following catheter placement of a stent in this vessel shortly after Fontan surgery. Percutaneous catheter aspiration thrombectomy was successfully performed. Percutaneous catheter aspiration thrombectomy may be considered as a viable option in acute thrombus in children with SV physiology after Fontan surgery.

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.

Anomalous origin of the right coronary artery evaluated with multidetector computed tomography and its clinical relevance

BACKGROUND Anomalous origin of the right coronary artery (AORCA) is a rare congenital anomaly that may cause myocardial ischemia and sudden death. METHODS We reviewed the clinicopathological records of three cases of AORCA, and compared these with two cases of sudden cardiac death with AORCA revealed by autopsy. RESULTS We report three juvenile cases with an AORCA originating above the commissural junction between the left and right aortic sinuses, with interarterial and intramural compression. They presented with exertional symptoms and were diagnosed with an AORCA by multidetector computed tomography (MDCT), which successfully delineated the spatial resolution of the anomalous origin and course of the right coronary artery (RCA), in the operating room. All three underwent successful surgical unroofing of the RCA. Two cases of sudden cardiac death with AORCA revealed by autopsy showed a slit-like orifice, acute-angled take-off, and long intramural course of the RCA, resembling the RCAs of three juvenile cases. CONCLUSIONS It is crucial to be alert to the presentation of exertional symptoms, as sudden death may be the first manifestation of an anomalous coronary artery, such as those observed in these three cases. MDCT provided an excellent definition and spatial resolution of the unusual origin and intramural course of the RCA, facilitating the correct surgical remedy and resulting in a good outcome for the patients.

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

BackgroundLeft 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 resultsWe 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.ConclusionsSarcomere 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.

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.