UBC Theses and Dissertations
Childhood allergic rhinitis : the role of the environment and genetics Fuertes, Elaine Isabelle
Allergic rhinitis is a global health problem that causes major illness and disability. Inherited and environmental factors influence its development. This thesis examined the role of traffic-related air pollution, genetic variants and their potential interactions, on childhood allergic rhinitis. Global spatial associations with climatic factors known to influence aeroallergen distributions were also studied. Data from two Canadian (CAPPS and SAGE) and four European birth cohorts (BAMSE, GINIplus, LISAplus and PIAMA) participating in the Traffic, Asthma and Genetics collaboration were pooled. No consistent associations between individual-level traffic-related air pollutants (NO2, PM2.5 mass, PM2.5 absorbance and ozone) estimated to the home address and childhood allergic rhinitis were observed in a longitudinal analysis (up to ten years) of two cohorts (GINIplus and LISAplus; N=6,604) and a pooled analysis of all six cohorts (N=15,299). These latter null associations were not modified by ten tested single nucleotide polymorphisms in the GSTP1, TNF, TLR2 and TLR4 genes. Although these results do not support an adverse role of traffic-related air pollution on childhood allergic rhinitis, much remains to be learned regarding for whom, when and how air pollution may impact disease. In further analyses, genetic variants in the TNF and TLR4 genes and at the 17q21 gene locus were found to be associated with childhood allergic rhinitis in pooled analyses of the six cohorts. As genetic variability in these regions has also been linked to asthma, the observed associations support the hypothesis of shared genetic susceptibility between asthma and allergic rhinitis. These results may be important for public health given the large proportion of the population carrying the studied risk variants. Lastly, using cross-sectional data from 6-7 and 13-14 year-olds participating in the International Study of Asthma and Allergies in Childhood, several ecological spatial associations between climatic factors (temperature, precipitation and vapour pressure) and intermittent and persistent rhinitis symptom prevalences were identified. Although not conclusive, these results represent a first step in investigating how climate change may affect rhinitis symptom prevalence. Collectively, this dissertation contributes to our understanding of the effects of air pollution, genetic variability and climate on childhood allergic rhinitis.
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