Prognostic predictive value of gene mutations in Japanese patients with hypertrophic cardiomyopathy.

Although some studies have attempted to find useful prognostic factors in hypertrophic cardiomyopathy (HCM), those results are not fully helpful for use in actual clinical practice. Furthermore, several genetic abnormalities associated with HCM have been identified. However, the genotype-phenotype correlation in HCM remains to be elucidated. Here, we attempted to assess patients with different types of gene mutations causing HCM and investigate the prognosis. A total of 140 patients with HCM underwent a screening test for myofilament gene mutations by direct sequencing of eight sarcomeric genes. Patients with a single mutation in cardiac troponin T, cardiac troponin I, α-tropomyosin, and regulatory and essential light chains were excluded from the study because the number of cases was too small. The clinical presentations and outcomes of the remaining 127 patients with HCM, 31 ß-myosin heavy chain (MYH7) mutation carriers, 19 cardiac myosin-binding protein C (MYBPC3) mutation carriers, and 77 mutation non-carriers were analyzed retrospectively. MYBPC3 mutation carriers had a high frequency of ventricular arrhythmia and syncope. Kaplan-Meier curves revealed no significant difference in prognosis among the three groups, but a lack of family history of sudden death (SD) and a past history of syncope were significantly related to poor prognosis. An absence of family history of SD and past history of syncope are useful prognostic factors in patients with HCM. MYH7 and MYBPC3 mutations did not significantly influence prognosis compared to non-carriers. However, patients with the MYBPC3 mutation should be closely followed for the possibility of SD.

Soluble ST2 and N-terminal pro-brain natriuretic peptide combination. Useful biomarker for predicting outcome of childhoodpulmonary arterial hypertension.

BACKGROUND: Some potential biomarkers have been reported recently in patients with pulmonary arterial hypertension (PAH), but the most clinically useful among these potential biomarkers, especially in childhood PAH, has not been identified. Therefore, this study investigated which biomarker is useful in assessing severity of and patient prognosis in childhood idiopathic PAH (IPAH)/heritable PAH (HPAH). METHODS AND RESULTS: Fifty-nine patients who were younger than 16 years at onset of IPAH/HPAH were selected. The following 10 biomarker candidates were quantified: high-sensitivity troponin T, human heart fatty acid-binding protein, N-terminal pro-brain natriuretic peptide (NT-proBNP), pentraxin-3, soluble ST2 (sST2), angiopoietin-2 (Ang-2), matrix metalloproteinase 2, tenascin C, endostatin (ES), and thymidine kinase. Functional characteristics and clinical outcomes were analyzed retrospectively. NT-proBNP, sST2, Ang-2, and ES correlated well with New York Heart Association class. On area under the receiver operating characteristic curve analysis, sST2 had a significantly good relationship with prognosis. On Kaplan-Meier curve and univariate Cox regression analyses, elevated sST2 and NT-proBNP level predicted poor outcome of the present patients with childhood IPAH/HPAH. Furthermore, patients with elevated sST2 had significantly worse prognosis among those with high NT-proBNP. CONCLUSIONS: The sST2 and NT-proBNP combination is a useful biomarker to predict clinical condition and outcome in patients with childhood IPAH/HPAH.

Missense mutations of the BMPR1B (ALK6) gene in childhood idiopathic pulmonary arterial hypertension.

BACKGROUND: Mutations in the bone morphogenetic protein receptor type 2 (BMPR2) gene, the activin receptor-like kinase 1 (ALK1) gene, and SMAD8 gene have been reported in heritable pulmonary arterial hypertension (HPAH) and in idiopathic pulmonary arterial hypertension (IPAH). However, almost 30% of HPAH cases and 60-90% of IPAH cases have no mutations in those genes. This suggests that there remain unidentified genes associated with HPAH and IPAH. METHODS AND RESULTS: This study screened for mutations in endoglin, SMAD1, SMAD2, SMAD3, SMAD4, SMAD5, SMAD6, SMAD7, bone morphogenetic protein receptor type 1A (BMPR1A) and bone morphogenetic protein receptor type 1B (BMPR1B) genes in 43 IPAH patients who had no mutations in BMPR2, ALK1 and SMAD8. Two missense mutations (c.479 G>A S160N, c.1176 C>A F392L) in BMPR1B were each identified in 2 IPAH patients. Immunoblot analysis revealed that the BMPR1B F392L protein promoted SMAD8 phosphorylation. The response to BMP was analyzed using promoter-reporter activities. The transcriptional activation of the BMPR1B F392L protein with SMAD8 increased above that of wild-type BMPR1B with SMAD8, and those of BMPR1B S160N and F392L with SMAD8 and SMAD4 were each increased above those of the wild-type BMPR1B with SMAD8 and SMAD4. CONCLUSIONS: We identified 2 novel mutations in BMPR1B in 2 patients with IPAH. Our study suggests that BMPR1B mutations are associated with the pathogenesis of IPAH.

Mutations of NOTCH3 in childhood pulmonary arterial hypertension.

Mutations of BMPR2 and other TGF-ß superfamily genes have been reported in pulmonary arterial hypertension (PAH). However, 60-90% of idiopathic PAH cases have no mutations in these genes. Recently, the expression of NOTCH3 was shown to be increased in the pulmonary artery smooth muscle cells of PAH patients. We sought to investigate NOTCH3 and its target genes in PAH patients and clarify the role of NOTCH3 signaling. We screened for mutations in NOTCH3, HES1, and HES5 in 41 PAH patients who had no mutations in BMPR2, ALK1, endoglin, SMAD1/4/8, BMPR1B, or Caveolin-1. Two novel missense mutations (c.2519 G>A p.G840E, c.2698 A>C p.T900P) in NOTCH3 were identified in two PAH patients. We performed functional analysis using stable cell lines expressing either wild-type or mutant NOTCH3. The protein-folding chaperone GRP78/BiP was colocalized with wild-type NOTCH3 in the endoplasmic reticulum, whereas the majority of GRP78/BiP was translocated into the nuclei of cells expressing mutant NOTCH3. Cell proliferation and viability were higher for cells expressing mutant NOTCH3 than for those expressing wild-type NOTCH3. We identified novel NOTCH3 mutations in PAH patients and revealed that these mutations were involved in cell proliferation and viability. NOTCH3 mutants induced an impairment in NOTCH3-HES5 signaling. The results may contribute to the elucidation of PAH pathogenesis.

ACVRL1 gene variant in a patient with vein of Galen aneurysmal malformation.

Although mutations in the RASA1 gene in vein of Galen aneurysmal malformation (VGAM) and an endoglin gene mutation in a VGAM patient with a family history of hereditary hemorrhagic telangiectasia (HHT) have been identified, most VGAM cases have no mutation in these genes. We sought to detect mutations in other genes related to HHT. We screened for mutations in RASA1 and three genes (endoglin, activin receptor-like kinase 1 (ACVRL1), encoding ALK1, and SMAD4) related to HHT in four VGAM patients. One variant (c.652 C>T p.R218W) in ACVRL1 was identified. Immunoblotting revealed that the ALK1-R218W protein could not promote SMAD1/5/8 phosphorylation by BMP9 stimulation. On the other hand, wild-type ALK1 could enhance the phosphorylation as expected. Furthermore, the transcriptional activation of ALK1-R218W was less efficient than that of wild-type ALK1. We identified 1 variant in ACVRL1 in a VGAM patient. These findings suggest that the ACVRL1 variant-R218W may be associated with the pathogenesis of VGAM.

Outcomes of childhood pulmonary arterial hypertension in BMPR2 and ALK1 mutation carriers.

Mutations in the bone morphogenetic protein receptor type 2 (BMPR2) gene and the activin receptor-like kinase 1 (ALK1) gene have been reported in heritable pulmonary arterial hypertension (HPAH) and idiopathic pulmonary arterial hypertension (IPAH). However, the relation between clinical characteristics and each gene mutation in IPAH and HPAH is still unclear, especially in childhood. The aim of this study was to determine, in a retrospective study, the influence and clinical outcomes of gene mutations in childhood IPAH and HPAH. Fifty-four patients with IPAH or HPAH whose onset of disease was at <16 years of age were included. Functional characteristics, hemodynamic parameters, and clinical outcomes were compared in BMPR2 and ALK1 mutation carriers and noncarriers. Overall 5-year survival for all patients was 76%. Eighteen BMPR2 mutation carriers and 7 ALK1 mutation carriers were detected in the 54 patients with childhood IPAH or HPAH. Five-year survival was lower in BMPR2 mutation carriers than mutation noncarriers (55% vs 90%, hazard ratio 12.54, p = 0.0003). ALK1 mutation carriers also had a tendency to have worse outcome than mutation noncarriers (5-year survival rate 64%, hazard ratio 5.14, p = 0.1205). In conclusion, patients with childhood IPAH or HPAH with BMPR2 mutation have the poorest clinical outcomes. ALK1 mutation carriers tended to have worse outcomes than mutation noncarriers. It is important to consider aggressive treatment for BMPR2 or ALK1 mutation carriers.

Cardiopulmonary arrest caused by craniometaphyseal dysplasia.

Craniometaphyseal dysplasia is a rare congenital disorder that can cause craniofacial skeleton and tubular bone anomalies. A 7-month-old girl, with congenital facial palsy, mouth breathing, and nasal obstruction, was brought to the hospital because she suffered sudden cardiopulmonary arrest. Computed tomography showed bony narrowing of the choanae. The diagnosis was cardiopulmonary arrest triggered by asphyxia caused by severe choanal stenosis. She showed hypoxic encephalopathy and underwent a tracheotomy and an operation to enlarge choanae. When a neonate or young infant shows signs of nasal obstruction, physicians should aggressively search for and consider the possibility of choanal atresia or severe stenosis.

Severe human herpesvirus 6-associated encephalopathy in three children: analysis of cytokine profiles and the carnitine palmitoyltransferase 2 gene.

Three children developed severe encephalopathy associated with human herpesvirus 6 infection. Magnetic resonance imaging of the brain showed either basal ganglia involvement or diffusion abnormalities in the cerebral white matter. Coagulopathy with hypercytokinemia was observed in 2 patients. One demonstrated thermolabile variation in carnitine palmitoyltransferase 2. These results suggest a heterogeneous pathogenic mechanism in encephalopathy associated with human herpesvirus 6 infection.

dup(8p)/del(8q) recombinant chromosome in a girl with hepatic focal nodular hyperplasia.

A 15-year-old girl had exertion dyspnea, focal nodular hyperplasia of the liver, portal vein hypoplasia, portopulmonary hypertension, mental retardation, and minor facial abnormalities. Cytogenetic analysis demonstrated an abnormal chromosome 8 with 8p22-pter duplication and 8q24.3-qter deletion, with the duplicated 8p segment attached to band 8q24.3. Her mother had a pericentric inversion of chromosome 8, inv(8)(p22q24.3). Therefore, the girl's abnormal chromosome 8 was a recombinant of maternal inversion chromosome: 46,XX,rec(8)dup(8p)inv(8)(p22q24.3)mat. Further characterization of the recombinant chromosome, using array CGH and regional FISH analyses, defined 15 Mb distal 8p duplication and 0.5 Mb 8q deletion. Possible correlation of the recombinant chromosome and hepatic focal nodular hyperplasia in the patient is discussed.