Funding outcome

Disorders of Immunoglobulin A (IgA) deficiency are on the rise worldwide. IgA is a common antibody made in the bone marrow against bacteria and viruses, and circulates in blood to protect us from infections. Children with low blood IgA levels more often have pneumonia, ear infections, asthma and even developmental delay. IgA is also made by gut cells. This type of IgA binds to the 'good' bacteria in our gut (called gut microbiota), which is critical for the development of the infant's immune system and protection against asthma. There are hints from published studies that our gut microbiota can influence the production of blood IgA. IgA-producing cells in infants are more plentiful in blood if their gut is colonized with certain bacteria after birth. All together, the limited literature points to the involvement of our early life gut microbiota in influencing blood IgA levels and playing a role in IgA deficiency disorders. The infant gut microbiome (types of gut bacteria and their metabolites) has been profiled in the 2009 CHILD Cohort Study, Canada's largest cohort of mother-newborn pairs. Infants have been followed until age 8 for asthma onset and their neurodevelopment was assessed at age 2. Records of blood IgA levels, ordered by physicians when diagnosing childhood conditions, are kept by provincial health care databases. CHILD study parents gave permission to link their infant's data to these health care database records, creating an opportunity for data linkage between infant gut microbiome profiles, asthma and neurodevelopment status, and blood IgA levels. Accessing this novel linked dataset, our research objectives are to determine: (i) whether the infant gut microbiome is associated with low blood IgA levels, and (ii) whether this association predicts low blood IgA levels in children with asthma or developmental delay. Differences by infant sex will be tested.