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Pulmonary arterial hypertension (PAH) is a rare disorder with a poor prognosis. Deleterious variation within components of the transforming growth factor-β pathway, particularly the bone morphogenetic protein type 2 receptor ( BMPR2 ), underlies most heritable forms of PAH. To identify the missing heritability we perform whole-genome sequencing in 1038 PAH index cases and 6385 PAH-negative control subjects. Case-control analyses reveal significant overrepresentation of rare variants in ATP13A3, AQP1 and SOX17 , and provide independent validation of a critical role for GDF2 in PAH. We demonstrate familial segregation of mutations in SOX17 and AQP1 with PAH. Mutations in GDF2 , encoding a BMPR2 ligand, lead to reduced secretion from transfected cells. In addition, we identify pathogenic mutations in the majority of previously reported PAH genes, and provide evidence for further putative genes. Taken together these findings contribute new insights into the molecular basis of PAH and indicate unexplored pathways for therapeutic intervention. Pulmonary arterial hypertension (PAH) is a rare lung disorder characterised by narrowing and obliteration of small pulmonary arteries ultimately leading to right heart failure. Here, the authors sequence whole genomes of over 1000 PAH patients and identify likely causal variants in GDF2 , ATP13A3 , AQP1 and SOX17 .

Background Symptoms of theophylline toxicity and factors that augment the risk of developing it are well documented in the literature. However these appear to be poorly considered in clinical practice. This case underlines the challenges in recognising and managing theophylline toxicity; moreover the requirement for improved application of knowledge of its pharmacokinetics to our practice. Case Presentation In this case we observe how theophylline toxicity can be overlooked due to the presence of non-specific symptoms and lack of a structured system to mitigate error in detection, in both hospital medicine and general practice. Here, the initial theophylline concentration measurement was documented as 59.3 mg/l in a patient taking the medication long-term, with the previous concentration being recorded one year prior. Management consisted of suspension of theophylline along with best supportive care, however in the process other conditions were exacerbated and the patient ultimately died in hospital. Congestive cardiac failure, congestive liver disease and polypharmacy were factors isolated from this case that expedited the patients’ development of theophylline toxicity. This was perpetuated by delay in diagnosis due to presentation with generalised symptoms including tachycardia, vomiting and neurological symptoms. Conclusions Findings from this case necessitate a requirement for more stringent monitoring of theophylline when taken chronically in those who demonstrate risk factors for toxicity. This would aim to prevent accumulation of the drug, toxicity onset and subsequent acute presentation to hospital. Intervention, through charcoal haemoperfusion may provide a means of enhanced recovery to reduce sequelae of toxicity.

Approximately 25% of patients with pulmonary arterial hypertension (PAH) have been found to harbor rare mutations in disease-causing genes. To identify missing heritability in PAH we integrated deep phenotyping with whole-genome sequencing data using Bayesian statistics. We analyzed 13,037 participants enrolled in the NIHR BioResource - Rare Diseases (NBR) study, of which 1,148 were recruited to the PAH domain. To test for genetic associations between genes and selected phenotypes of pulmonary hypertension (PH), we used the Bayesian rare-variant association method BeviMed. Heterozygous, high impact, likely loss-of-function variants in the Kinase Insert Domain Receptor (KDR) gene were strongly associated with significantly reduced transfer coefficient for carbon monoxide (KCO, posterior probability (PP)=0.989) and older age at diagnosis (PP=0.912). We also provide evidence for familial segregation of a rare nonsense KDR variant with these phenotypes. On computed tomographic imaging of the lungs, a range of parenchymal abnormalities were observed in the five patients harboring these predicted deleterious variants in KDR. Four additional PAH cases with rare likely loss-of-function variants in KDR were independently identified in the US PAH Biobank cohort with similar phenotypic characteristics. The Bayesian inference approach allowed us to independently validate KDR, which encodes for the Vascular Endothelial Growth Factor Receptor 2 (VEGFR2), as a novel PAH candidate gene. Furthermore, this approach specifically associated high impact likely loss-of-function variants in the genetically constrained gene with distinct phenotypes. These findings provide evidence for KDR being a clinically actionable PAH gene and further support the central role of the vascular endothelium in the pathobiology of PAH.

Pulmonary arterial hypertension (PAH) is a rare disorder with a poor prognosis. Deleterious variation within components of the transforming growth factor- pathway, particularly the bone morphogenetic protein type 2 receptor (BMPR2), underlie most heritable forms of PAH. Since the missing heritability likely involves genetic variation confined to small numbers of cases, we performed whole genome sequencing in 1038 PAH index cases and 6385 PAH-negative control subjects. Case-control analyses revealed significant overrepresentation of rare variants in novel genes, namely ATP13A3, AQP1 and SOX17, and provided independent validation of a critical role for GDF2 in PAH. We provide evidence for familial segregation of mutations in SOX17 and AQP1 with PAH. Mutations in GDF2, encoding a BMPR2 ligand, led to reduced secretion from transfected cells. In addition, we identified pathogenic mutations in the majority of previously reported PAH genes, and provide evidence for further putative genes. Taken together these findings provide new insights into the molecular basis of PAH and indicate unexplored pathways for therapeutic intervention.

Objectives To assess the feasibility and reliability of the use of artificial intelligence post-processing to calculate the RV:LV diameter ratio on computed tomography pulmonary angiography (CTPA) and to investigate its prognostic value in patients with acute PE. Methods Single-centre, retrospective study of 101 consecutive patients with CTPA-proven acute PE. RV and LV volumes were segmented on 1-mm contrast-enhanced axial slices and maximal ventricular diameters were derived for RV:LV ratio using automated post-processing software (IMBIO LLC, USA) and compared to manual analysis in two observers, via intraclass coefficient correlation analysis. Each CTPA report was analysed for mention of the RV:LV ratio and compared to the automated RV:LV ratio. Thirty-day all-cause mortality post-CTPA was recorded. Results Automated RV:LV analysis was feasible in 87% ( n = 88). RV:LV ratios ranged from 0.67 to 2.43, with 64% ( n = 65) > 1.0. There was very strong agreement between manual and automated RV:LV ratios (ICC = 0.83, 0.77–0.88). The use of automated analysis led to a change in risk stratification in 45% of patients ( n = 40). The AUC of the automated measurement for the prediction of all-cause 30-day mortality was 0.77 (95% CI: 0.62–0.99). Conclusion The RV:LV ratio on CTPA can be reliably measured automatically in the majority of real-world cases of acute PE, with perfect reproducibility. The routine use of this automated analysis in clinical practice would add important prognostic information in patients with acute PE. Key Points • Automated calculation of the right ventricle to left ventricle ratio was feasible in the majority of patients and demonstrated perfect intraobserver variability. • Automated analysis would have added important prognostic information and altered risk stratification in the majority of patients. • The optimal cut-off value for the automated right ventricle to left ventricle ratio was 1.18, with a sensitivity of 100% and specificity of 54% for the prediction of 30-day mortality.

BackgroundAnaemia is common in left heart failure and is associated with a poorer outcome. Many patients with pulmonary arterial hypertension (PAH) are anaemic or iron-deficient. This study was performed to investigate the prevalence of iron deficiency in PAH and to identify possible causes.MethodsAll patients with idiopathic or heritable PAH diagnosed in 1995–2008 were identified. Controls were selected from patients with chronic thromboembolic pulmonary hypertension (CTEPH). Full blood counts were examined and any abnormality was investigated. Patients were excluded if they had a cause for iron deficiency. The prevalence study was based on 85 patients with idiopathic PAH and 120 with CTEPH. A separate group of 20 patients with idiopathic PAH and 24 with CTEPH with matching haemodynamics were prospectively investigated for serum factors affecting iron metabolism.ResultsThe prevalence study identified a point prevalence of unexplained iron deficiency of 50% in premenopausal women with idiopathic PAH compared with 8% in premenopausal women with CTEPH (p=0.002); 14% in postmenopausal women with idiopathic PAH compared with 6% in postmenopausal women with CTEPH (p=0.16); 28% in men with idiopathic PAH men compared with 2% in men with CTEPH (p=0.002); and 60% in patients with heritable PAH. The serum study showed that patients with idiopathic PAH had lower serum iron and transferrin saturations than those with CTEPH. Interleukin-6 levels correlated with iron levels(r=−0.6, p=0.006) and transferrin saturations (r=−0.68, p=0.001) in idiopathic PAH but not in CTEPH.ConclusionsThe prevalence of unexplained iron deficiency is significantly higher in idiopathic PAH than in CTEPH. This may be linked to interleukin-6.