Rationale: Several studies suggest that nasal nitric oxide (nNO)
measurement could be a test for primary ciliary dyskinesia (PCD), but the procedure
and interpretation have not been standardized.
Objectives: To use a standard protocol for measuring nNO to establish a
disease-specific cutoff value at one site, and then validate at six other sites.
Methods: At the lead site, nNO was prospectively measured in individuals
later confirmed to have PCD by ciliary ultrastructural defects (n = 143) or
DNAH11 mutations (n = 6); and in 78 healthy and 146 disease
control subjects, including individuals with asthma (n = 37), cystic fibrosis (n
= 77), and chronic obstructive pulmonary disease (n = 32). A
disease-specific cutoff value was determined, using generalized estimating equations
(GEEs). Six other sites prospectively measured nNO in 155 consecutive individuals
enrolled for evaluation for possible PCD.
Measurements and Main Results: At the lead site, nNO values in PCD (mean
± standard deviation, 20.7 ± 24.1 nl/min; range, 1.5–207.3 nl/min)
only rarely overlapped with the nNO values of healthy control subjects (304.6 ±
118.8; 125.5–867.0 nl/min), asthma (267.8 ± 103.2; 125.0–589.7
nl/min), or chronic obstructive pulmonary disease (223.7 ± 87.1;
109.7–449.1 nl/min); however, there was overlap with cystic fibrosis (134.0
± 73.5; 15.6–386.1 nl/min). The disease-specific nNO cutoff value was
defined at 77 nl/minute (sensitivity, 0.98; specificity, >0.999). At six other
sites, this cutoff identified 70 of the 71 (98.6%) participants with confirmed
Conclusions: Using a standardized protocol in multicenter studies, nNO
measurement accurately identifies individuals with PCD, and supports its usefulness
as a test to support the clinical diagnosis of PCD.
primary ciliary dyskinesia; Kartagener syndrome; ciliopathy; axoneme
Primary ciliary dyskinesia (PCD) is a rare, autosomal recessive, genetically heterogeneous disorder characterized by ciliary dysfunction resulting in chronic oto-sino-pulmonary disease, respiratory distress in term neonates, laterality (situs) defects, and bronchiectasis. Diagnosis has traditionally relied on ciliary ultrastructural abnormalities seen by electron microscopy. Mutations in radial spoke head proteins occur in PCD patients with central apparatus defects. Advances in genetic testing have been crucial in addressing the diagnostic challenge. Here, we describe a novel splice-site mutation (c.921+3_6delAAGT) in RSPH4A, which leads to a premature translation termination signal in nine subjects with PCD (seven families). Loss-of-function was confirmed with quantitative ciliary ultrastructural analysis, measurement of ciliary beat frequency and waveform, and transcript analysis. All nine individuals carrying c.921+3_6delAAGT splice-site mutation in RSPH4A were Hispanic with ancestry tracing to Puerto Rico. This mutation is a founder mutation and a common cause of PCD without situs abnormalities in patients of Puerto Rican descent.
Cilia; Kartagener syndrome; sequencing; RSPH4A
Background: There is growing recognition and understanding of the entities that cause interstitial lung disease (ILD) in infants. These entities are distinct from those that cause ILD in older children and adults.
Methods: A multidisciplinary panel was convened to develop evidence-based guidelines on the classification, diagnosis, and management of ILD in children, focusing on neonates and infants under 2 years of age. Recommendations were formulated using a systematic approach. Outcomes considered important included the accuracy of the diagnostic evaluation, complications of delayed or incorrect diagnosis, psychosocial complications affecting the patient’s or family’s quality of life, and death.
Results: No controlled clinical trials were identified. Therefore, observational evidence and clinical experience informed judgments. These guidelines: (1) describe the clinical characteristics of neonates and infants (<2 yr of age) with diffuse lung disease (DLD); (2) list the common causes of DLD that should be eliminated during the evaluation of neonates and infants with DLD; (3) recommend methods for further clinical investigation of the remaining infants, who are regarded as having “childhood ILD syndrome”; (4) describe a new pathologic classification scheme of DLD in infants; (5) outline supportive and continuing care; and (6) suggest areas for future research.
Conclusions: After common causes of DLD are excluded, neonates and infants with childhood ILD syndrome should be evaluated by a knowledgeable subspecialist. The evaluation may include echocardiography, controlled ventilation high-resolution computed tomography, infant pulmonary function testing, bronchoscopy with bronchoalveolar lavage, genetic testing, and/or lung biopsy. Preventive care, family education, and support are essential.
diffuse lung disease; lung growth abnormalities; surfactant proteins; neuroendocrine cells
Examination of ciliary ultrastructure remains the cornerstone diagnostic test for primary ciliary dyskinesia (PCD), a disease of abnormal ciliary structure and/or function. Obtaining a biopsy with sufficient interpretable cilia and producing quality transmission electron micrographs (TEM) is challenging. Methods for processing tissues for optimal preservation of axonemal structures are not standardized. This study describes our experience using a standard operating procedure (SOP) for collecting nasal scrape biopsies and processing TEMs in a centralized laboratory. We enrolled patients with suspected PCD at research sites of the Genetic Disorders of Mucociliary Clearance Consortium. Biopsies were performed according to a SOP whereby curettes were used to scrape the inferior surface of the inferior turbinate, with samples placed in fixative. Specimens were shipped to a central laboratory where TEMs were prepared and blindly reviewed. 448 specimens were obtained from 107 young children (0–5 years), 189 older children (5–18 years), and 152 adults (> 18 years), and 88% were adequate for formal interpretation. The proportion of adequate specimens was higher in adults than in children. 50% of the adequate TEMs showed normal ciliary ultrastructure, 39% showed hallmark ultrastructural changes of PCD, and 11% had indeterminate findings. Among specimens without clearly normal ultrastructure, 72% had defects of the outer and/or inner dynein arms, while 7% had central apparatus defects with or without inner dynein arm defects. In summary, nasal scrape biopsies can be performed in the outpatient setting and yield interpretable samples, when performed by individuals with adequate training and experience according to an SOP.
cilia; nasal biopsy; primary ciliary dyskinesia
Primary ciliary dyskinesia (PCD) is an autosomal recessive, genetically heterogeneous disorder characterized by oto-sino-pulmonary disease and situs abnormalities (Kartagener syndrome) due to abnormal structure and/or function of cilia. Most patients currently recognized to have PCD have ultrastructural defects of cilia; however, some patients have clinical manifestations of PCD and low levels of nasal nitric oxide, but normal ultrastructure, including a few patients with biallelic mutations in DNAH11.
In order to test further for mutant DNAH11 as a cause of PCD, we sequenced DNAH11 in patients with a PCD clinical phenotype, but no known genetic etiology.
We sequenced 82 exons and intron/exon junctions in DNAH11 in 163 unrelated patients with a clinical phenotype of PCD, including those with normal ciliary ultrastructure (n=58), defects in outer ± inner dynein arms (n=76), radial spoke/central pair defects (n=6), and 23 without definitive ultrastructural results, but who had situs inversus (n=17), or bronchiectasis and/or low nasal nitric oxide (n=6). Additionally, we sequenced DNAH11 in 13 patients with isolated situs abnormalities to see if mutant DNAH11 could cause situs defects without respiratory disease.
Of the 58 unrelated PCD patients with normal ultrastructure, 13 (22%) had two (biallelic) mutations in DNAH11; plus, 2 PCD patients without ultrastructural analysis had biallelic mutations. All mutations were novel and private. None of the patients with dynein arm or radial spoke/central pair defects, or isolated situs abnormalities, had mutations in DNAH11. Of the 35 identified mutant alleles, 24 (69%) were nonsense, insertion/deletion or Ioss-of-function splice-site mutations.
Mutations in DNAH11 are a common cause of PCD in patients without ciliary ultrastructural defects; thus, genetic analysis can be used to ascertain the diagnosis of PCD in this challenging group of patients.
Cilia; Dynein; Kartagener syndrome; Dextrocardia; Heterotaxy
Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder of motile cilia. Most of the disease-causing mutations identified to date involve the heavy (DNAH5) or intermediate (DNAI1) chain dynein genes in ciliary outer dynein arms, although a few mutations have been noted in other genes. Clinical molecular genetic testing for PCD is available for the most common mutations. The respiratory manifestations of PCD (chronic bronchitis leading to bronchiectasis, chronic rhino-sinusitis and chronic otitis media) reflect impaired mucociliary clearance owing to defective axonemal structure. Ciliary ultrastructural analysis in most patients (>80%) reveals defective dynein arms, although defects in other axonemal components have also been observed. Approximately 50% of PCD patients have laterality defects (including situs inversus totalis and, less commonly, heterotaxy and congenital heart disease), reflecting dysfunction of embryological nodal cilia. Male infertility is common and reflects defects in sperm tail axonemes. Most PCD patients have a history of neonatal respiratory distress, suggesting that motile cilia play a role in fluid clearance during the transition from a fetal to neonatal lung. Ciliopathies involving sensory cilia, including autosomal dominant or recessive polycystic kidney disease, Bardet-Biedl syndrome, and Alstrom syndrome, may have chronic respiratory symptoms and even bronchiectasis suggesting clinical overlap with PCD.
Primary ciliary dyskinesia; PCD; Kartagener syndrome; situs inversus; dynein
Exposure to traffic-related air pollution (TRAP) can adversely impact health but epidemiologic studies are limited in their abilities to assess long-term exposures and incorporate variability in indoor pollutant infiltration.
In order to examine settled house dust levels of hopanes, engine lubricating oil byproducts found in vehicle exhaust, as a novel TRAP exposure measure, dust samples were collected from 171 homes in five Canadian cities and analyzed by gas chromatography–mass spectrometry. To evaluate source contributions, the relative abundance of the highest concentration hopane monomer in house dust was compared to that in outdoor air. Geographic variables related to TRAP emissions and outdoor NO2 concentrations from city-specific TRAP land use regression (LUR) models were calculated at each georeferenced residence location and assessed as predictors of variability in dust hopanes.
Hopanes relative abundance in house dust and ambient air were significantly correlated (Pearson’s r=0.48, p<0.05), suggesting that dust hopanes likely result from traffic emissions. The proportion of variance in dust hopanes concentrations explained by LUR NO2 was less than 10% in Vancouver, Winnipeg and Toronto while the correlations in Edmonton and Windsor explained 20 to 40% of the variance. Modeling with household factors such as air conditioning and shoe removal along with geographic predictors related to TRAP generally increased the proportion of explained variability (10-80%) in measured indoor hopanes dust levels.
Hopanes can consistently be detected in house dust and may be a useful tracer of TRAP exposure if determinants of their spatiotemporal variability are well-characterized, and when home-specific factors are considered.
Air pollution; Dust; Exposure assessment; Hopanes; Land use regression; Traffic
In 2010, the Canadian Thoracic Society (CTS) published a Consensus Summary for the diagnosis and management of asthma in children six years of age and older, and adults, including an updated Asthma Management Continuum. The CTS Asthma Clinical Assembly subsequently began a formal clinical practice guideline update process, focusing, in this first iteration, on topics of controversy and/or gaps in the previous guidelines.
Four clinical questions were identified as a focus for the updated guideline: the role of noninvasive measurements of airway inflammation for the adjustment of anti-inflammatory therapy; the initiation of adjunct therapy to inhaled corticosteroids (ICS) for uncontrolled asthma; the role of a single inhaler of an ICS/long-acting beta2-agonist combination as a reliever, and as a reliever and a controller; and the escalation of controller medication for acute loss of asthma control as part of a self-management action plan. The expert panel followed an adaptation process to identify and appraise existing guidelines on the specified topics. In addition, literature searches were performed to identify relevant systematic reviews and randomized controlled trials. The panel formally assessed and graded the evidence, and made 34 recommendations.
The updated guideline recommendations outline a role for inclusion of assessment of sputum eosinophils, in addition to standard measures of asthma control, to guide adjustment of controller therapy in adults with moderate to severe asthma. Appraisal of the evidence regarding which adjunct controller therapy to add to ICS and at what ICS dose to begin adjunct therapy in children and adults with poor asthma control supported the 2010 CTS Consensus Summary recommendations. New recommendations for the adjustment of controller medication within written action plans are provided. Finally, priority areas for future research were identified.
The present clinical practice guideline is the first update of the CTS Asthma Guidelines following the Canadian Respiratory Guidelines Committee’s new guideline development process. Tools and strategies to support guideline implementation will be developed and the CTS will continue to regularly provide updates reflecting new evidence.
Asthma; Clinical practice guideline; Management
Primary ciliary dyskinesia (PCD) is a rare genetic disease characterized by abnormal ciliary structure and function leading to impaired mucociliary clearance and chronic progressive sinopulmonary disease. Upper and lower respiratory tract manifestations are cardinal features of PCD. This review summarizes the current state of knowledge of respiratory tract disease in individuals with PCD and highlights the challenges in identifying and quantifying lung disease in very young children with PCD. No specific therapies are available to correct ciliary dysfunction in PCD. Treatment is not evidence based, and recommendations are largely extrapolated from cystic fibrosis and other conditions with impaired mucociliary clearance. There is a pressing need to develop and validate outcome measures, including patient-reported outcomes, that could be used to evaluate potential therapies in PCD. This review concludes with recommendations for clinical endpoints and outcome measures and a prioritized list of treatments to study in PCD clinical trials.
primary ciliary dyskinesia; lung disease; outcome measure; patient-reported outcome; clinical trial
Epinephrine autoinjectors provide life-saving therapy for individuals with peanut allergies.
To evaluate the association between socioeconomic status (SES) and epinephrine prescription among urban Canadian children with peanut allergy.
Population-based survey data from school children in grades 1 and 2 participating in the Toronto Child Health Evaluation Questionnaire were used. Children with peanut allergy, their epinephrine autoinjector prescription status and their SES were identified by parental report.
Between January and April 2006, 5619 completed questionnaires from 231 Toronto, Ontario, schools were returned. A total of 153 (2.83%) children were identified as having a peanut allergy, 68.6% of whom reported being prescribed an epinephrine autoinjector. Children from upper-middle and high-income homes (OR 8.35 [95% CI 2.72 to 25.61]) and with asthma (OR 4.74 [95% CI 1.56 to 14.47]) were more likely to report having an epinephrine prescription.
A significant health disparity exists in the prescribing pattern of epinephrine autoinjectors for peanut-allergic children from families of differing SES.
Epidemiology; Health disparities; Peanut allergy; Socioeconomic status
Childhood asthma prevalence is widely measured by parental proxy report of physician-diagnosed asthma in questionnaires. Our objective was to validate this measure in a North American population.
The 2884 study participants were a subsample of 5619 school children aged 5 to 9 years from 231 schools participating in the Toronto Child Health Evaluation Questionnaire study in 2006. We compared agreement between "questionnaire diagnosis" and a previously validated "health claims data diagnosis". Sensitivity, specificity and kappa were calculated for the questionnaire diagnosis using the health claims diagnosis as the reference standard.
Prevalence of asthma was 15.7% by questionnaire and 21.4% by health claims data. Questionnaire diagnosis was insensitive (59.0%) but specific (95.9%) for asthma. When children with asthma-related symptoms were excluded, the sensitivity increased (83.6%), and specificity remained high (93.6%).
Our results show that parental report of asthma by questionnaire has low sensitivity but high specificity as an asthma prevalence measure. In addition, children with "asthma-related symptoms" may represent a large fraction of under-diagnosed asthma and they should be excluded from the inception cohort for risk factor studies.
Asthma is the most common chronic disease in children.
To describe the prevalence of asthma and allergic disease in a multiethnic, population-based sample of Toronto (Ontario) school children attending grades 1 and 2.
In 2006, the Toronto Child Health Evaluation Questionnaire (T-CHEQ) used the International Study of Asthma and Allergies in Childhood survey methodology to administer questionnaires to 23,379 Toronto school children attending grades 1 and 2. Modifications were made to the methodology to conform with current privacy legislation and capture the ethnic diversity of the population. Lifetime asthma, wheeze, hay fever and eczema prevalence were defined by parental report. Asthma was considered to be current if the child also reported wheeze or asthma medication use in the previous 12 months.
A total of 5619 children from 283 randomly sampled public schools participated. Children were five to nine years of age, with a mean age of 6.7 years. The overall prevalence of lifetime asthma was 16.1%, while only 11.3% had current asthma. The reported prevalence of lifetime wheeze was 29.2%, while 14.2% reported wheeze in the past 12 months. Sociodemographic and major health determinant characteristics of the T-CHEQ population were similar to 2001 census data, suggesting a diverse sample that was representative of the urban childhood population.
Asthma continues to be a highly prevalent chronic disease in Canadian children. A large proportion of children with reported lifetime asthma, who were five to nine years of age, did not report current asthma symptomatology or medication use.
Childhood asthma; Epidemiology; Survey research
To integrate new evidence into the Canadian Asthma Management Continuum diagram, encompassing both pediatric and adult asthma.
The Canadian Thoracic Society Asthma Committee members, comprised of experts in pediatric and adult respirology, allergy and immunology, emergency medicine, general pediatrics, family medicine, pharmacoepidemiology and evidence-based medicine, updated the continuum diagram, based primarily on the 2008 Global Initiative for Asthma guidelines, and performed a focused review of literature pertaining to key aspects of asthma diagnosis and management in children six years of age and over, and adults.
In patients six years of age and over, management of asthma begins with establishing an accurate diagnosis, typically by supplementing medical history with objective measures of lung function. All patients and caregivers should receive self-management education, including a written action plan. Inhaled corticosteroids (ICS) remain the first-line controller therapy for all ages. When asthma is not controlled with a low dose of ICS, the literature supports the addition of long-acting beta2-agonists in adults, while the preferred approach in children is to increase the dose of ICS. Leukotriene receptor antagonists are acceptable as second-line monotherapy and as an alternative add-on therapy in both age groups. Anti-immunoglobulin E therapy may be of benefit in adults, and in children 12 years of age and over with difficult to control allergic asthma, despite high-dose ICS and at least one other controller.
The foundation of asthma management is establishing an accurate diagnosis based on objective measures (eg, spirometry) in individuals six years of age and over. Emphasis is placed on the similarities and differences between pediatric and adult asthma management approaches to achieve asthma control.
Asthma; Guidelines; Management
Although individuals spend the majority of their time indoors, most epidemiological studies estimate personal air pollution exposures based on outdoor levels. This almost certainly results in exposure misclassification as pollutant infiltration varies between homes. However, it is often not possible to collect detailed measures of infiltration for individual homes in large-scale epidemiological studies and thus there is currently a need to develop models that can be used to predict these values. To address this need, we examined infiltration of fine particulate matter (PM2.5) and identified determinants of infiltration for 46 residential homes in Toronto, Canada. Infiltration was estimated using the indoor/outdoor sulphur ratio and information on hypothesized predictors of infiltration were collected using questionnaires and publicly available databases. Multiple linear regression was used to develop the models. Mean infiltration was 0.52 ± 0.21 with no significant difference across heating and non-heating seasons. Predictors of infiltration were air exchange, presence of central air conditioning, and forced air heating. These variables accounted for 38% of the variability in infiltration. Without air exchange, the model accounted for 26% of the variability. Effective modelling of infiltration in individual homes remains difficult, although key variables such as use of central air conditioning show potential as an easily attainable indicator of infiltration.
air exchange; air quality; indoor; infiltration; fine particulate matter; PM2.5; residential; sulphur
Home characteristic questions are used in epidemiological studies and clinical settings to assess potentially harmful exposures in the home. The objective of this study was to determine whether questionnaire-reported home characteristics can predict directly measured pollutants. Sixty home inspections were conducted on a subsample of the 2006 population-based Toronto Child Health Evaluation Questionnaire. Indoor/outdoor air and settled dust samples were analyzed. Mean Fel d 1 was higher (p < 0.0001) in homes with a cat (450.58 μg/g) versus without (22.28 μg/g). Mean indoor NO2 was higher (p = 0.003) in homes with gas stoves (14.98 ppb) versus without (8.31 ppb). Self-reported musty odours predicted higher glucan levels (10554.37 μg/g versus 6308.58 μg/g, p = 0.0077). Der f 1 was predicted by the home’s age, but not by reports of carpets, and was higher in homes with mean relative humidity > 50% (61.30 μg/g, versus 6.24 μg/g, p = 0.002). Self-reported presence of a cat, a gas stove, musty odours, mice, and the home’s age and indoor relative humidity over 50% predicted measured indoor levels of cat allergens, NO2, fungal glucan, mouse allergens and dust mite allergens, respectively. These results are helpful for understanding the significance of indoor exposures ascertained by self-reporting in large epidemiological studies and also in the clinical setting.
allergens; environmental exposure; house dust; indoor air pollution; questionnaire
Pulmonary alveolar proteinosis (PAP) is a syndrome with multiple etiologies and is often deadly in lysinuric protein intolerance (LPI). At present, PAP is treated by whole lung lavage or with granulocyte/monocyte colony stimulating factor (GM-CSF); however, the effectiveness of GM-CSF in treating LPI associated PAP is uncertain. We hypothesized that GM-CSF and surfactant protein D (SP-D) would enhance the clearance of proteins and dying cells that are typically present in the airways of PAP lungs.
Cells and cell-free supernatant of therapeutic bronchoalveolar lavage fluid (BALF) of a two-year-old patient with LPI were isolated on multiple occasions. Diagnostic BALF samples from an age-matched patient with bronchitis or adult PAP patients were used as controls. SP-D and total protein content of the supernatants were determined by BCA assays and Western blots, respectively. Cholesterol content was determined by a calorimetic assay or Oil Red O staining of cytospin preparations. The cells and surfactant lipids were also analyzed by transmission electron microscopy. Uptake of Alexa-647 conjugated BSA and DiI-labelled apoptotic Jurkat T-cells by BAL cells were studied separately in the presence or absence of SP-D (1 μg/ml) and/or GM-CSF (10 ng/ml), ex vivo. Specimens were analyzed by light and fluorescence microscopy.
Here we show that large amounts of cholesterol, and large numbers of cholesterol crystals, dying cells, and lipid-laden foamy alveolar macrophages were present in the airways of the LPI patient. Although SP-D is present, its bioavailability is low in the airways. SP-D was partially degraded and entrapped in the unusual surfactant lipid tubules with circular lattice, in vivo. We also show that supplementing SP-D and GM-CSF increases the uptake of protein and dying cells by healthy LPI alveolar macrophages, ex vivo. Serendipitously, we found that these cells spontaneously generated granulomas, ex vivo, and GM-CSF treatment drastically increased the number of granulomas whereas SP-D treatment counteracted the adverse effect of GM-CSF.
We propose that increased GM-CSF and decreased bioavailability of SP-D may promote granuloma formation in LPI, and GM-CSF may not be suitable for treating PAP in LPI. To improve the lung condition of LPI patients with PAP, it would be useful to explore alternative therapies for increasing dead cell clearance while decreasing cholesterol content in the airways.
Rationale: Considerable confusion exists regarding nomenclature, classification, and management of pediatric diffuse lung diseases due to the relative rarity and differences in the spectrum of disease between adults and young children.
Objectives: A multidisciplinary working group was formed to: (1) apply consensus terminology and diagnostic criteria for disorders presenting with diffuse lung disease in infancy; and (2) describe the distribution of disease entities, clinical features, and outcome in young children who currently undergo lung biopsy in North America.
Methods: Eleven centers provided pathologic material, clinical data, and imaging from all children less than 2 years of age who underwent lung biopsy for diffuse lung disease from 1999 to 2004.
Measurements and Main Results: Multidisciplinary review categorized 88% of 187 cases. Disorders more prevalent in infancy, including primary developmental and lung growth abnormalities, neuroendocrine cell hyperplasia of infancy, and surfactant-dysfunction disorders, constituted the majority of cases (60%). Lung growth disorders were often unsuspected clinically and under-recognized histologically. Cases with known surfactant mutations had characteristic pathologic features. Age at biopsy and clinical presentation varied among categories. Pulmonary hypertension, presence of a primary developmental abnormality, or ABCA3 mutation was associated with high mortality, while no deaths occurred in cases of pulmonary interstitial glycogenosis, or neuroendocrine cell hyperplasia of infancy.
Conclusions: This retrospective cohort study identifies a diverse spectrum of lung disorders, largely unique to young children. Application of a classification scheme grouped clinically distinct patients with variable age of biopsy and mortality. Standardized terminology and classification will enhance accurate description and diagnosis of these disorders.
infant; pulmonary; interstitial lung disease; surfactant; neuroendocrine hyperplasia