The future is here: Integrating genetics into the pediatric pulmonary clinic

Recognition of underlying genetic etiologies of disease is increasing at an exponential rate, likely due to greater access to and lower cost of genetic testing. Monogenic causes of disease, or conditions resulting from a mutation or mutations in a single gene, are now well recognized in every subspecialty, including pediatric pulmonary medicine; thus, it is important to consider genetic conditions when evaluating children with respiratory disease. In the pediatric pulmonary clinic, genetic testing should be considered when multiple family members present with similar or related clinical features and when individuals have unusual clinical presentations, such as early-onset disease or complex, syndromic features. This review provides a practical guide for genetic diagnosis in the pediatric pulmonary setting, including a review of genetic concepts, considerations for test selection and results in interpretation, as well as an overview of genetic differential diagnoses for common pediatric pulmonary phenotypes. Genetic conditions that commonly present to the pediatric pulmonary clinic are reviewed in a companion article by Yonker et al.

Childhood diffuse parenchymal lung diseases: We need a new classification

INTRODUCTION

Childhood diffuse parenchymal lung diseases (DPLD) are a heterogeneous group of respiratory disorders of both known and unknown causes that share common histological features. To date, there is not an exact consensus about the terminology, classification, therapy and follow up of this disease because of its rarity and wide clinical spectrum.

OBJECTIVES

In this study, we tried to classify our DPLD patients according to the last classification scheme (chILD Network Classification).

METHODS

The files of the children diagnosed with DPLD at our university hospital between 1974 and 2012 were retrospectively investigated. Clinical features, laboratory, radiological and histopathological findings, therapy and follow-up outcomes of these patients were recorded and evaluated according to the actual information and definitions.

RESULTS

We described 130 DPLD patients, the largest childhood DPLD series from a single center, classified in 16 distinct groups according to their diagnosis. Our largest group in this serie is pulmonary hemosiderosis (28.5%); idiopathic interstitial pneumonias, pulmonary hemosiderosis, sarcoidosis and lipid storage diseases with lung involvement represent the 70% of the diagnoses. When we classified our patients according to the chILD Network Classification; patients with idiopathic interstitial pneumonia older than 2 years, idiopathic pulmonary hemosiderosis, pulmonary alveolar microlithiasis and diffuse chondroid malformation of the lung stayed out of this classification.

CONCLUSION

To ensure a consensus about the therapy and follow up, we have to make revisions and reorganisations on the DPLD classification which was proposed in 2007. We need a new childhood DPLD classification that will cover all these disease groups.

Pediatric pulmonology year in review 2017: Part 1

Pediatric Pulmonology publishes original research, case reports and review articles on topics related to a wide range of children's respiratory disorders. In this article (Part 1 of a series), we summarize the past year's publications in our major topic areas, as well as selected literature in these areas from other journals. In Part 1, we review selected articles on diagnostic testing/endoscopy, respiratory complications of neuromuscular disorders, and rare lung diseases.

mTOR-Notch3 signaling mediates pulmonary hypertension in hypoxia-exposed neonatal rats independent of changes in autophagy

BACKGROUND/AIM

Mammalian target of rapamycin (mTOR) is a pivotal regulator of cell proliferation, survival, and autophagy. Autophagy is increased in adult experimental chronic pulmonary hypertension (PHT), but its contributory role to pulmonary vascular disease remains uncertain and has yet to be explored in the neonatal animal. Notch is a major pro-proliferative pathway activated by mTOR. A direct relationship between autophagy and Notch signaling has not been previously explored. Our aim was to examine changes in mTOR-, Notch-, and autophagy-related pathways and the therapeutic effects of autophagy modulators in experimental chronic neonatal PHT secondary to chronic hypoxia.

METHODS

Rat pups were exposed to normoxia or hypoxia (13% O₂ ) from postnatal days 1-21, while receiving treatment with temsirolimus (mTOR inhibitor), DAPT (Notch inhibitor), or chloroquine (inhibitor of autophagic flux).

RESULTS

Exposure to hypoxia up-regulated autophagy and Notch3 signaling markers in lung, pulmonary artery (PA), and PA-derived smooth muscle cells (SMCs). Temsirolimus prevented chronic PHT and attenuated PA and SMC signaling secondary to hypoxia. These effects were replicated by DAPT. mTOR or Notch inhibition also down-regulated smooth muscle content of platelet-derived growth factor β-receptor, a known contributor to vascular remodeling. In contrast, chloroquine had no modifying effects on markers of chronic PHT. Knockdown of Beclin-1 in SMCs had no effect on hypoxia-stimulated Notch3 signaling.

CONCLUSIONS

mTOR-Notch3 signaling plays a critical role in experimental chronic neonatal PHT. Inhibition of autophagy did not suppress Notch signaling and had no effect on markers of chronic PHT.

Asymptomatic pulmonary arteriovenous malformations in children with hereditary hemorrhagic telangiectasia

BACKGROUND

Children with Hereditary Hemorrhagic Telangiectasia (HHT) may have pulmonary arteriovenous malformations (AVMs), which can lead to symptoms of shortness of breath, exercise intolerance, clubbing, cyanosis and hemoptysis. However, some patients with pulmonary AVMs may be asymptomatic, placing them at risk for complications such as stroke or brain abscess if they are not identified and treated. This study examines the incidence of signs and symptoms associated with pulmonary AVMs in children with HHT known to have pulmonary AVMs.

METHOD

Sixty-one children with HHT and documented pulmonary AVMs were questioned for any symptoms possibly associated with their pulmonary AVMs, prior to embolization.

RESULTS

The results show that the majority of these children were asymptomatic (56%), and their AVMs were discovered by routine screening. Those who did experience symptoms most often complained of shortness of breath and exercise intolerance, although there was a tendency to blame other conditions, such as asthma or deconditioning (being out of shape), for these symptoms. Migraine headaches were common in those with pulmonary AVMs, regardless of whether they were symptomatic or not (17 of 61 children, 28%), although they were more common in those who were symptomatic (10 of 27, 37%) versus those who were asymptomatic (7 of 34, 21%).

CONCLUSION

Children with HHT and pulmonary AVMs are often asymptomatic. Routine screening for the presence of AVMs should be performed regardless of symptomatology.

Pulmonary arterial wall thickness in Eisenmenger Syndrome: Prospective, cross-sectional, controlled clinical trial

BACKGROUND

The aim of current study is to investigate echocardiographic pulmonary artery wall thickness (PAWT) association with angiocardiography, echocardiography, and biochemical findings and to demonstrate its predictive role in morbidity of disease.

METHOD

Nineteen patients with Eisenmenger Syndrome (ES) (13 females; a mean age of 12.0 ± 4.1 [min-max 4-17] years) and 24 (16 females; a mean age of 12.1 ± 4.3 [min-max 3-18 years]) healthy subjects as a control group were included in this prospective, cross-sectional, controlled clinical study between December, 2012 and December, 2013. PAWT were measured at the end of systole at the distal site of pulmonary valves at the parasternal short-axis. PAWT was compared with morbidity criteria of the disease such as functional class, pulmonary vascular resistance.

RESULTS

PAWT was higher in the patient group (P = 0.005) together with pulmonary arterial diameter (Z-score, P < 0.001), vena cava inferior diameter (P = 0.002), and right ventricular wall thickness (RVWT), while TAPSE was significantly lower (P = 0.002). PAWT was strongly positively correlated to RVWT (r = 0.893, P < 0.001) and moderate negatively correlated to TAPSE (r = 0.597; P < 0.011).

CONCLUSION

PAWT can be used as an additional parameter with other echocardiographic parameters in the follow-up of Eisenmenger Syndrome in children.

A physician survey reveals differences in management of idiopathic pulmonary hemosiderosis

BACKGROUND

Idiopathic pulmonary hemosiderosis (IPH) is a rare disorder of unknown etiology characterized by chronic pulmonary hemorrhage and presents with a triad of anemia, hemoptysis and pulmonary infiltrates. IPH is a diagnosis of exclusion with a variable and disparate clinical course. Despite existing therapies, few children achieve full remission while others have recurrent hemorrhage, progressive lung damage, and premature death.

METHODS

We surveyed physicians who care for patients with IPH via a web-based survey to assess the most common practices. 88 providers responded, caring for 274 IPH patients from five continents.

RESULTS

63.3 % of respondents had patients that were initially misdiagnosed with anemia (60.0 %) or gastrointestinal bleed (18.2 %). Respondents varied in diagnostic tools used for evaluation. The key difference was in the use of lung biopsy (51.9 %) for diagnosis. Common medications respondents used for treatment at initial presentation and chronic maintenance therapy were corticosteroids (98.7 and 84.0 %, initial and chronic therapy respectively), hydroxychloroquine (33.3 and 64.0 %), azathioprine (8.0 and 37.3 %), and cyclophosphamide (4.0 and 16.0 %). There was agreement on the use of corticosteroids for exacerbation amongst all respondents. Reported deaths before adulthood occurred in 7.3 % of patients. We conclude that there were common features and specific variations in physician management of IPH. Respondents were divided on whether to perform lung biopsy for diagnosis.

CONCLUSION

Despite the availability of various immunomodulators, corticosteroids remained the primary therapy. We speculate that the standardization of care for diffuse alveolar hemorrhage will improve patient outcomes.