The natural history of asthma from childhood to adulthood

Asthma remission one, none and one-hundred thousand: the relevance of the patient's view

OBJECTIVE

Achieving remission in severe asthma holds paramount importance in elevating patient quality of life and reducing both individual and societal burdens associated with this chronic condition. This study centers on identifying pivotal patient-relevant endpoints through standardized, reproducible methods, while also developing a patient-centric definition of remission, essential for effective disease management.

METHODS

A discrete choice experiment (DCE) was conducted to assess patients' perceptions on the four primary criteria for defining severe asthma remission, as outlined by the SANI survey. Additionally, it investigated the correlation between these perceptions and improvements in the doctor-patient therapeutic alliance during treatment decision-making.

RESULTS

249 patients (70% aged between 31-60, 59% women and 82% without other pathologies requiring corticosteroids) prioritize the use of oral corticosteroids (OCS, 48%) and the Asthma Control Test (ACT, 27%) in defining their condition, ranking these above lung function and exacerbations. This preference for OCS stems from its direct role in treatment, tangible tracking, immediate symptom relief, and being a concrete measure of disease severity compared to the less predictable and quantifiable exacerbations.

CONCLUSIONS

This study explores severe asthma remission from patients' perspectives using clinician-evaluated parameters. The DCE revealed that most patients highly value OCS and the ACT, prefer moderate improvement, and avoid cortisone cycles. No definitive preference was found for lung function status. Integrating patient-reported information with professional insights is crucial for effective management and future research. Personalized treatment plans focusing on patient preferences, adherence, and alternative therapies aim to achieve remission and enhance quality of life.

Associations between asthma and cognitive functioning among older adults. Does the age of asthma diagnosis matter? Results from the RAND IFLS-5 study

OBJECTIVE

To assess the associations of asthma status or age at asthma diagnosis with cognition using the Telephone Survey of Cognitive Status from a large population-based sample. Further, we investigated the possibility that asthma treatment mediates these associations.

METHODS

This is a cross-sectional study from the Indonesian Family Life Survey Fifth Wave (IFLS-5) collected in 2014-2015. A weighted linear regression model was used to examine the associations between asthma and cognitive functioning scores in adults aged 50 years or older. Of the 6660 total samples included in this study, 176 participants had asthma (2.6%). We controlled for age, sex, and urbanicity with further adjustments for adult covariates or childhood covariates, as appropriate.

RESULTS

There was no association between overall asthma status and cognitive functioning scores. However, asthma diagnosed at 0-19 years was associated with significantly higher cognitive functioning scores (Beta coefficient = 2.24, 95% CI: 0.62 - 0.87), compared to those without asthma. In the analysis involving current treatment status (restricted analysis), the significant association disappeared among those under current asthma treatment status, indicating that asthma treatment may mediate the association.

CONCLUSION

Asthma might not be a risk factor for cognitive impairment. Observations of a significant association of pediatric asthma with higher cognitive scores need further investigation. Understanding cognitive functioning among older adults with asthma may improve the surveillance of cognitive decline inthis age group.

Prediction of adult asthma risk in early childhood using novel adult asthma predictive risk scores

BACKGROUND

Numerous risk scores have been developed to predict childhood asthma. However, they may not predict asthma beyond childhood. We aim to create childhood risk scores that predict development and persistence of asthma up to young adult life.

METHODS

The Isle of Wight Birth Cohort (n = 1456) was prospectively assessed up to 26 years of age. Asthma predictive scores were developed based on factors during the first 4 years, using logistic regression and tested for sensitivity, specificity and area under the curve (AUC) for prediction of asthma at (i) 18 and (ii) 26 years, and persistent asthma (PA) (iii) at 10 and 18 years, and (iv) at 10, 18 and 26 years. Models were internally and externally validated.

RESULTS

Four models were generated for prediction of each asthma outcome. ASthma PredIctive Risk scorE (ASPIRE)-1: a 2-factor model (recurrent wheeze [RW] and positive skin prick test [+SPT] at 4 years) for asthma at 18 years (sensitivity: 0.49, specificity: 0.80, AUC: 0.65). ASPIRE-2: a 3-factor model (RW, +SPT and maternal rhinitis) for asthma at 26 years (sensitivity: 0.60, specificity: 0.79, AUC: 0.73). ASPIRE-3: a 3-factor model (RW, +SPT and eczema at 4 years) for PA-18 (sensitivity: 0.63, specificity: 0.87, AUC: 0.77). ASPIRE-4: a 3-factor model (RW, +SPT at 4 years and recurrent chest infection at 2 years) for PA-26 (sensitivity: 0.68, specificity: 0.87, AUC: 0.80). ASPIRE-1 and ASPIRE-3 scores were replicated externally. Further assessments indicated that ASPIRE-1 can be used in place of ASPIRE-2-4 with same predictive accuracy.

CONCLUSION

ASPIRE predicts persistent asthma up to young adult life.

Factors Associated with Persistence of Severe Asthma from Late Adolescence to Early Adulthood

RATIONALE

Asthma severity in children generally starts mild but may progress and stay severe for unknown reasons.

OBJECTIVES

Identify factors in childhood that predict persistence of severe asthma in late adolescence and early adulthood.

METHODS

The Childhood Asthma Management Program is the largest and longest asthma trial in 1041 children aged 5-12 years with mild to moderate asthma. We evaluated 682 participants from the program with analyzable data in late adolescence (age 17-19) and early adulthood (age 21-23).

MEASUREMENTS

Severe asthma was defined using criteria from the American Thoracic Society and the National Asthma Education and Prevention Program to best capture severe asthma. Logistic regression with stepwise elimination was used to analyze clinical features, biomarkers, and lung function predictive of persistence of severe asthma.

MAIN RESULTS

In late adolescence and early adulthood 12% and 19% of the patents had severe asthma, respectively; only 6% were severe at both time periods. For every 5% decrease in post bronchodilator FEV1/FVC in childhood, the odds of persistence of severe asthma increased 2.36-fold (95% CI: 1.70-3.28; p <0.0001), for participants with maternal smoking during pregnancy odds of persistence of severe asthma increased 3.17-fold (95% CI: 1.18-8.53, p=0.02). Reduced growth lung function trajectory was significantly associated with persistence of severe asthma compared to normal growth.

CONCLUSIONS

Lung function and maternal smoking during pregnancy were significant predictors of severe asthma from late adolescence to early adulthood. Interventions to preserve lung function early may prevent disease progression.

Remission and Changes in Severity Over 30 Years in an Adult Asthma Cohort

BACKGROUND

Long-term follow-up studies of adults with well-characterized asthma are sparse.

OBJECTIVE

We aimed to examine long-term remission and change in disease severity over 30 years in adults with asthma.

METHODS

A total of 125 individuals diagnosed with asthma between 1974 and 1990 at a Danish respiratory and allergy clinic, based on history and objective assessments, were included. At follow-up (2017-2019), participants completed questionnaires and had spirometry, bronchodilator reversibility, airway responsiveness, and blood biomarkers measured. Based on these assessments, participants were classified as having either active asthma, clinical remission (no symptoms or prescribed asthma medication within the last year), or complete remission (fractional exhaled nitric oxide <50 parts per billion, no bronchodilator reversibility, no airway hyperresponsiveness, and no airflow limitation). Changes in severity were determined according to Global Initiative for Asthma guidelines based on symptom control and currently prescribed medication.

RESULTS

At follow-up, 25% (n = 31) and 15% (n = 19), respectively, had clinical and complete remission. Our analyses showed that a longer duration of symptoms before the initial assessment (odds ratio, 0.86; 95% confidence interval, 0.75-0.98) was associated with a lower chance of asthma remission. At follow-up, 30% had well-controlled asthma compared with none at baseline. Female sex, previous severe exacerbation(s), and older age at baseline were associated with uncontrolled asthma at follow-up. Blood-eosinophil count (≥0.3 × 10⁹/L) and prescribed inhaled corticosteroid (ICS) at baseline were associated with being prescribed medium/high-dose ICS at follow-up.

CONCLUSION

Despite 30 years of follow-up, asthma rarely remits in adults, especially in individuals with longer duration and presumably more severe disease. Initial signs of pronounced disease activity were associated with uncontrolled asthma at follow-up.

Barriers and Facilitators to Asthma Care After Hospitalization as Reported by Caregivers, Health Providers, and School Nurses

OBJECTIVES

To develop a comprehensive understanding of the barriers and/or facilitators for asthma management for the health professionals and caregivers of children with >1 hospitalization.

METHODS

Individual interviews were conducted with family caregivers and health professionals. Focus groups were conducted with school nurses. The interview and focus group guide were used to probe for barriers and facilitators of asthma management. Interviews were recorded, transcribed, and coded by using qualitative software. Themes were identified by using content analysis in the interviews and descriptive qualitative analysis in the focus groups.

RESULTS

Caregivers (n = 10), asthma educators (n = 4), physicians (n = 4), and a payer (n = 1) were individually interviewed. School nurses were interviewed via a focus group (n = 10). Children had a median age of 7 years, mean length of stay of 1.9 days, and 56% had a previous hospitalization in the previous 12 months. The "gaps in asthma knowledge" theme (which includes an inadequate understanding of asthma chronicity, activity restrictions, and management with controller medications) emerged as a theme for both caregivers and health professionals but with different health beliefs. School nurses reinforced the difficulty they have in managing children who have asthma in schools, and they identified using the asthma action plan as a facilitator.

CONCLUSIONS

Caregivers and health professionals have different health beliefs about asthma knowledge, which raises challenges in the care of a child who has asthma. In addition, school nurses highlight specific barriers that are focused on medication use in schools. A comprehensive understanding of the barriers and facilitators of asthma management that families experience after hospital discharge is crucial to design better efforts to support families.

The MEGA Project: A Study of the Mechanisms Involved in the Genesis and Disease Course of Asthma. Asthma Cohort Creation and Long-Term Follow-Up

The general aim of this study is to create a cohort of asthma patients with varying grades of severity in order to gain greater insight into the mechanisms underlying the genesis and course of this disease. The specific objectives focus on various studies, including imaging, lung function, inflammation, and bronchial hyperresponsiveness, to determine the relevant events that characterize the asthma population, the long-term parameters that can determine changes in the severity of patients, and the treatments that influence disease progression. The study will also seek to identify the causes of exacerbations and how this affects the course of the disease. Patients will be contacted via the outpatient clinics of the 8 participating institutions under the auspices of the Spanish Respiratory Diseases Networking System (CIBER). In the inclusion visit, a standardized clinical history will be obtained, a clinical examination, including blood pressure, body mass index, complete respiratory function tests, and FENO will be performed, and the Asthma Control Test (ACT), Morisky-Green test, Asthma Quality of Life Questionnaire (Mini AQLQ), the Sino-Nasal Outcome Test 22 (SNOT-22), and the Hospital Anxiety and Depression scale (HADS) will be administered. A specific electronic database has been designed for data collection. Exhaled breath condensate, urine and blood samples will also be collected. Non-specific bronchial hyperresponsiveness testing with methacholine will be performed and an induced sputum sample will be collected at the beginning of the study and every 24 months. A skin prick test for airborne allergens and a chest CT will be performed at the beginning of the study and repeated every 5 years.

Association Between Bacillus Calmette-Guérin Vaccination and Childhood Asthma in the Quebec Birth Cohort on Immunity and Health

We estimated the association between bacillus Calmette-Guérin (BCG) vaccination and childhood asthma in a birth cohort using administrative databases, and we determined the impact of adjusting for potential confounders collected from a subset of the cohort members. Data were collected in 2 waves: 1) Administrative data for 76,623 individuals (stage 1) was gathered from the Quebec Birth Cohort on Immunity and Health (1974-1994), including BCG vaccination status, perinatal and sociodemographic characteristics, and use of health services for asthma; and 2) self-reported asthma risk factors were collected in 2012 by telephone interviews with 1,643 participants (stage 2) using a balanced 2-stage sampling design. We estimated odds ratios and 95% confidence intervals for asthma using logistic regression and correcting for the known sampling fractions from stage 1 to stage 2, overall and sex-stratified. In total, 35,612 (46.5%) individuals were BCG vaccinated, and 5,870 (7.7%) had asthma. The final odds ratio, integrating results from both stages of sampling, was 0.95 (95% confidence interval: 0.87, 1.04). Results did not differ according to sex (P for interaction = 0.327). To our knowledge, this is the largest study ever conducted on this topic, and using the best possible comprehensive adjustment for confounders, we found no association between BCG vaccination and asthma.

Inhaled corticosteroids improve lung function, airway hyper-responsiveness and airway inflammation but not symptom control in patients with mild intermittent asthma: A meta-analysis

It remains controversial whether inhaled corticosteroid (ICS) should be used in patients with intermittent asthma. The present study aimed to assess the effect of ICS compared with placebo or other therapies in patients with intermittent asthma. Medline, Embase and CNKI databases were searched up to June 2016 and a meta-analysis was conducted. The findings demonstrated that in adult patients, when compared with placebo, ICS increased forced expiratory volume in 1 sec FEV1 [standardized mean difference (SMD), 0.51; 95% confidence interval (CI), 0.22-0.80] and alleviated airway hyper-responsiveness, which was indicated as log transformed PC20FEV1 (concentrations of methacholine when there was a fall in FEV1 ≥20%; SMD, 0.87; 95% CI, 0.60 to 1.14). ICS also reduced fractional exhaled nitric oxide (FeNO) levels [weighted mean difference (WMD), -12.57 parts per billion (ppb; a unit of NO concentration in exhaled air); 95% CI -15.88 to -9.25 ppb]. However, symptom scores did not change after ICS treatment (SMD, -0.26; 95% CI, -0.52 to 0). When compared with leukotriene receptor antagonists (LTRA), ICS had no advantage in increasing FEV1 (WMD, 0.04 l; 95% CI, -0.06 to 0.13 l), reducing sputum eosinophil percentage (WMD, -6%; 95% CI, -12.38 to 0.38%) or symptom scores (SMD, 0.44; 95% CI, -0.02 to 0.9). However, in child patients, ICS significantly (P<0.05) increased the possibility of symptom control when compared with placebo [relative risk (RR), 8; 95% CI, 1.04 to 61.52] or LTRA (RR, 2.67; 95% CI, 0.39 to 18.42). In conclusion, ICS improves lung function and alleviates airway hyper-responsiveness and airway inflammation but cannot influence symptom scores, and has no advantage over LTRA in terms of lung function improvement and airway inflammation control in adult patients with mild intermittent asthma. However, in children, the benefit of ICS in symptom control is more significant than with LTRA.

Monitoring asthma in childhood

The goal of asthma treatment is to obtain clinical control and reduce future risks to the patient. However, to date there is limited evidence on how to monitor patients with asthma. Childhood asthma introduces specific challenges in terms of deciding what, when, how often, by whom and in whom different assessments of asthma should be performed. The age of the child, the fluctuating course of asthma severity, variability in clinical presentation, exacerbations, comorbidities, socioeconomic and psychosocial factors, and environmental exposures may all influence disease activity and, hence, monitoring strategies. These factors will be addressed in herein.

We identified large knowledge gaps in the effects of different monitoring strategies in children with asthma. Studies into monitoring strategies are urgently needed, preferably in collaborative paediatric studies across countries and healthcare systems.

Monitoring asthma in children is essential for disease control and should reflect age, triggers and disease activityhttp://ow.ly/J0k7f

Declines with age in childhood asthma symptoms and health care use: an adjustment for evaluations

RATIONALE

Asthma is a variable condition with an apparent tendency for a natural decline in asthma symptoms and health care use occurring as children age. As a result, asthma interventions using a pre-post design may overestimate the intervention effect when no proper control group is available.

OBJECTIVES

Investigate patterns of natural decline over time with increasing age in asthma symptoms and health care use of children. Develop a statistical procedure that enables adjustment that accounts for expected declines in these outcomes and is useable when intervention evaluations must rely solely on pre-post data.

METHODS

Mixed-effects models with mixture distributions were used to describe the pattern of symptoms and health care use in 3,021 children aged 2 to 15 years in a combined sample from three controlled trials. An adaptive least squares estimation was used to account for overestimation of intervention effects and make adjustments for pre-post only data. Termed "Adjustment for Natural Declines in Asthma Outcomes (ANDAO)," the adjustment method uses bootstrap sampling to create control cohorts comparable to subjects in the intervention study from existing control subjects. ANDAO accounts for expected declines in outcomes and is beneficial when intervention evaluations must rely solely on pre-post data.

MEASUREMENTS AND MAIN RESULTS

Children under 10 years of age experienced 18% (95% confidence interval, 15-21%) fewer symptom days and 28% (95% confidence interval, 24-32%) fewer symptom nights with each additional year of age. The decline was less than 10% after age 10 years, depending on baseline asthma severity. Emergency department visits declined regardless of baseline symptom frequency (P = 0.02). The adjustment method corrected estimates to within 2.4% of true effects through simulations using control cohorts.

CONCLUSIONS

Because of the declines in symptoms and health care use expected with increasing age of children with asthma, pre-post comparisons will greatly overestimate intervention effects. The ANDAO provides means to adequately estimate treatment effects when a control group design is not possible.

Prognosis of new-onset asthma diagnosed at adult age

BACKGROUND

Asthma is a common chronic disease, which can affect patients at any age. Recently, cluster analyses have suggested that patients with asthma can be divided into different phenotypes and that the age at the onset of the disease is a critical defining factor. The prognosis of allergic childhood-onset asthma is relatively well known, whereas the prognosis of adult-onset asthma remains unclear.

METHODS

We undertook a systematic review to identify studies that evaluated the long-term prognosis of new-onset asthma diagnosed at adult age. Criteria used (set 1) were: 1. adult-onset asthma, 2. physician diagnosed asthma (including objective lung-functions) < 1 year before the first visit, 3. follow-up time of at least 5 years, 4. objective lung function measurements used at follow-up and 5. not a comparative trial. Another set of studies (set 2) with less strict criteria were gathered.

RESULTS

The main result of this systematic review is that the amount of evidence on the prognosis of new-onset asthma diagnosed at adult age is very limited. Only one study (n = 250) fulfilled the criteria (set 1) and it suggests that the five-year prognosis of new-onset asthma diagnosed at adult age may not be favorable, the proportion of patients being in remission was less than 5%. Furthermore, six additional follow-up studies (n = 964) were identified including mainly patients with adult-onset asthma (set 2). These studies had variable endpoints and the results could not be combined.

CONCLUSION

Further follow-up studies that recruit patients with new-onset adult asthma are needed to understand the prognostic factors in adult-onset asthma.

Monitoring asthma in children

The goal of asthma treatment is to obtain clinical control and reduce future risks to the patient. To reach this goal in children with asthma, ongoing monitoring is essential. While all components of asthma, such as symptoms, lung function, bronchial hyperresponsiveness and inflammation, may exist in various combinations in different individuals, to date there is limited evidence on how to integrate these for optimal monitoring of children with asthma. The aims of this ERS Task Force were to describe the current practise and give an overview of the best available evidence on how to monitor children with asthma. 22 clinical and research experts reviewed the literature. A modified Delphi method and four Task Force meetings were used to reach a consensus. This statement summarises the literature on monitoring children with asthma. Available tools for monitoring children with asthma, such as clinical tools, lung function, bronchial responsiveness and inflammatory markers, are described as are the ways in which they may be used in children with asthma. Management-related issues, comorbidities and environmental factors are summarised. Despite considerable interest in monitoring asthma in children, for many aspects of monitoring asthma in children there is a substantial lack of evidence.

Declines with age in childhood asthma symptoms and health care use. An adjustment for evaluations

RATIONALE

Asthma is a variable condition with an apparent tendency for a natural decline in asthma symptoms and health care use occurring as children age. As a result, asthma interventions using a pre-post design may overestimate the intervention effect when no proper control group is available.

OBJECTIVES

Investigate patterns of natural decline over time with increasing age in asthma symptoms and health care use of children. Develop a statistical procedure that enables adjustment that accounts for expected declines in these outcomes and is useable when intervention evaluations must rely solely on pre-post data.

METHODS

Mixed-effects models with mixture distributions were used to describe the pattern of symptoms and health care use in 3,021 children aged 2 to 15 years in a combined sample from three controlled trials. An adaptive least squares estimation was used to account for overestimation of intervention effects and make adjustments for pre-post only data. Termed "Adjustment for Natural Declines in Asthma Outcomes (ANDAO)," the adjustment method uses bootstrap sampling to create control cohorts comparable to subjects in the intervention study from existing control subjects. ANDAO accounts for expected declines in outcomes and is beneficial when intervention evaluations must rely solely on pre-post data.

MEASUREMENTS AND MAIN RESULTS

Children under 10 years of age experienced 18% (95% confidence interval, 15-21%) fewer symptom days and 28% (95% confidence interval, 24-32%) fewer symptom nights with each additional year of age. The decline was less than 10% after age 10 years, depending on baseline asthma severity. Emergency department visits declined regardless of baseline symptom frequency (P = 0.02). The adjustment method corrected estimates to within 2.4% of true effects through simulations using control cohorts.

CONCLUSIONS

Because of the declines in symptoms and health care use expected with increasing age of children with asthma, pre-post comparisons will greatly overestimate intervention effects. The ANDAO provides means to adequately estimate treatment effects when a control group design is not possible.

The role of the γ δ T cell in allergic diseases

The predominant distribution of γδ T cells in the mucosal and epithelial tissues makes these unconventional lymphocytes the “guards” to contact external environment (like allergens) and to contribute to immune surveillance, as well as “vanguards” to participate in initiating mucosal inflammation. Therefore, γδ T cells have been considered to bridge the innate and adaptive immunity. The role these cells play in allergy seems to be complicated and meaningful, so it makes sense to review the characteristics and role of γδ T cells in allergic diseases.

Prognostic bases of asthma. Natural history?

Different causes of asthma have been established. The most common cause is conditioned to a genetic predisposition towards atopy (atopic asthma), although other factors can also give rise to bronchial inflammation, such as over-exposure to environmental irritants (occupational asthma), altered arachidonic acid metabolism (aspirin-induced asthma) and also exercise - in which different thermal and osmotic mechanisms are known to intervene. The prognosis of these different variants of asthma depends on the severity of the condition; patient age at onset of the disease; patient age at the time of diagnosis; the treatment provided; and adherence to therapy. The concept of "natural history" refers to the spontaneous evolution or course of the disease process in the absence of pathogenic or etiological treatment, with the provision of only symptomatic treatment. In order to gain increased certainty regarding the course of these patients, the study groups must present similar baseline characteristics in terms of the start and severity of the condition; the start of treatment; compliance; and the clinical and functional control findings.

Relationship between silent gastroesophageal reflux and food sensitization in infants and young children with recurrent wheezing

It is known that early childhood wheezing associated with sensitization to allergens, including food, has an increased risk of developing asthma later during school age. Gastroesophageal reflux (GER) is well known to be associated with asthma. The purpose of this study was to determine whether there is an association between silent GER and food sensitization in infants and young children with recurrent wheezing. Eighty-five infants or young children with recurrent wheezing, and no gastrointestinal symptoms, underwent 24 hr esophageal pH monitoring, as well as total serum IgE and specific IgE testing for eggs and milk. Among the 85 subjects, 48.2% had significant GER. There was no significant difference in the GER between atopic and non-atopic recurrent wheezers (41.7% and 50.8%, respectively). The sensitization rate to food (eggs or milk) was 12.2% and 20.5% in the GER and non-GER groups, respectively and showed no statistically significant difference between the two groups (P=0.34). In conclusion, about half of infants and young children with recurrent wheezing and no gastrointestinal symptoms have silent GER. The silent GER may not contribute to food sensitization in infants and young children with recurrent wheezing.

The ontogeny, distribution, and regulation of alcohol dehydrogenase 3: implications for pulmonary physiology

Class III alcohol dehydrogenase (ADH3), also termed formaldehyde dehydrogenase or S-nitrosoglutathione reductase, plays a critical role in the enzymatic oxidation of formaldehyde and reduction of nitrosothiols that regulate bronchial tone. Considering reported associations between formaldehyde vapor exposure and childhood asthma risk, and thus potential involvement of ADH3, we reviewed the ontogeny, distribution, and regulation of mammalian ADH3. Recent studies indicate that multiple biological and chemical stimuli influence expression and activity of ADH3, including the feedback regulation of nitrosothiol metabolism. The levels of ADH3 correlate with, and potentially influence, bronchial tone; however, data gaps remain with respect to the expression of ADH3 during postnatal and early childhood development. Consideration of ADH3 function relative to the respiratory effects of formaldehyde, as well as to other chemical and biological exposures that might act in an additive or synergistic manner with formaldehyde, might be critical to gain better insight into the association between formaldehyde exposure and childhood asthma.

Genetic variation in immune signaling genes differentially expressed in asthmatic lung tissues

BACKGROUND

Eight genes in the immune signaling pathway shown to be differentially expressed in asthmatic lung biopsy specimens in a previous microarray experiment were selected as candidate genes for asthma susceptibility.

OBJECTIVE

We sought to perform an association study with these genes and asthma-related phenotypes in 3 independent Canadian familial asthma collections and 1 Australian asthma case-control study.

METHODS

Tagging single nucleotide polymorphisms were selected by using the HapMap public database (r(2) > 0.8; minor allele frequency >0.10) and genotyped with the Illumina platform. Family-based association and trend tests for asthma, atopy, airway hyperresponsiveness, and allergic asthma phenotypes were done in each sample, correcting for multiple testing.

RESULTS

Uncorrected associations with polymorphisms within 7 genes were detected with 1 or more of the phenotypes in 1 or more of the 4 populations (.001 <P < .05). After correction, the 15-lipoxygenase (15-LO) associations with airway hyperresponsiveness and allergic asthma remained significant in 2 Canadian samples (corrected P = .022 and .049, respectively), and the association of the CD14 antigen with asthma remained significant in 1 Canadian sample (corrected P = .042). In both cases a protective effect of the minor alleles was observed.

CONCLUSION

Expression profiling studies are a useful way to identify candidate genes for asthma because this approach has led to the first report of an association with 15-LO in 2 independent populations. Because 15-LO is involved in anti-inflammatory processes, further functional and clinical investigation of the role of this biologic pathway in asthma is warranted.

Genes to diseases (G2D) computational method to identify asthma candidate genes

Asthma is a complex trait for which different strategies have been used to identify its environmental and genetic predisposing factors. Here, we describe a novel methodological approach to select candidate genes for asthma genetic association studies. In this regard, the Genes to Diseases (G2D) computational tool has been used in combination with a genome-wide scan performed in a sub-sample of the Saguenay−Lac-St-Jean (SLSJ) asthmatic familial collection (n = 609) to identify candidate genes located in two suggestive loci shown to be linked with asthma (6q26) and atopy (10q26.3), and presenting differential parent-of-origin effects. This approach combined gene selection based on the G2D data mining analysis of the bibliographic and protein public databases, or according to the genes already known to be associated with the same or a similar phenotype. Ten genes (LPA, NOX3, SNX9, VIL2, VIP, ADAM8, DOCK1, FANK1, GPR123 and PTPRE) were selected for a subsequent association study performed in a large SLSJ sample (n = 1167) of individuals tested for asthma and atopy related phenotypes. Single nucleotide polymorphisms (n = 91) within the candidate genes were genotyped and analysed using a family-based association test. The results suggest a protective association to allergic asthma for PTPRE rs7081735 in the SLSJ sample (p = 0.000463; corrected p = 0.0478). This association has not been replicated in the Childhood Asthma Management Program (CAMP) cohort. Sequencing of the regions around rs7081735 revealed additional polymorphisms, but additional genotyping did not yield new associations. These results demonstrate that the G2D tool can be useful in the selection of candidate genes located in chromosomal regions linked to a complex trait.